Category: mysqli

MySQLi – Regexps ”; Previous Next You have seen MySQL pattern matching with LIKE …%. MySQL supports another type of pattern matching operation based on regular expressions and the REGEXP operator. If you are aware of PHP or PERL, then it”s very simple for you to understand because this matching is very similar to those scripting regular expressions. Following is the table of pattern, which can be used along with REGEXP operator. Pattern What the pattern matches ^ Beginning of string $ End of string . Any single character […] Any character listed between the square brackets [^…] Any character not listed between the square brackets p1|p2|p3 Alternation; matches any of the patterns p1, p2, or p3 * Zero or more instances of preceding element + One or more instances of preceding element {n} n instances of preceding element {m,n} m through n instances of preceding element Examples Now based on above table, you can device various type of SQL queries to meet your requirements. Here, I”m listing few for your understanding. Consider we have a table called tutorials_inf and it”s having a field called name − Query to find all the names starting with ”sa” mysql> SELECT * FROM tutorials_inf WHERE name REGEXP ”^sa”; The sample output should be like this − +—-+——+ | id | name | +—-+——+ | 1 | sai | +—-+——+ 1 row in set (0.00 sec) Query to find all the names ending with ”ai” mysql> SELECT * FROM tutorials_inf WHERE name REGEXP ”ai$”; The sample output should be like this − +—-+——+ | id | name | +—-+——+ | 1 | sai | +—-+——+ 1 row in set (0.00 sec) Query to find all the names, which contain ”a” mysql> SELECT * FROM tutorials_inf WHERE name REGEXP ”a”; The sample output should be like this − +—-+——-+ | id | name | +—-+——-+ | 1 | sai | | 3 | ram | | 4 | johar | +—-+——-+ 3 rows in set (0.00 sec) Query to find all the names starting with a vowel mysql> SELECT * FROM tutorials_inf WHERE name REGEXP ”^[aeiou]”; Print Page Previous Next Advertisements ”;

MySQLi – Temporary Tables ”; Previous Next The temporary tables could be very useful in some cases to keep temporary data. The most important thing that should be known for temporary tables is that they will be deleted when the current client session terminates. As stated earlier, temporary tables will only last as long as the session is alive. If you run the code in a PHP script, the temporary table will be destroyed automatically when the script finishes executing. If you are connected to the MySQL database server through the MySQL client program, then the temporary table will exist until you close the client or manually destroy the table. Example Here is an example showing you usage of temporary table. Same code can be used in PHP scripts using mysqli_query() function. mysql> CREATE TEMPORARY TABLE SalesSummary ( → product_name VARCHAR(50) NOT NULL → , total_sales DECIMAL(12,2) NOT NULL DEFAULT 0.00 → , avg_unit_price DECIMAL(7,2) NOT NULL DEFAULT 0.00 → , total_units_sold INT UNSIGNED NOT NULL DEFAULT 0 → ); Query OK, 0 rows affected (0.00 sec) mysql> INSERT INTO SalesSummary → (product_name, total_sales, avg_unit_price, total_units_sold) → VALUES → (”cucumber”, 100.25, 90, 2); mysql> SELECT * FROM SalesSummary; +————–+————-+—————-+——————+ | product_name | total_sales | avg_unit_price | total_units_sold | +————–+————-+—————-+——————+ | cucumber | 100.25 | 90.00 | 2 | +————–+————-+—————-+——————+ 1 row in set (0.00 sec) When you issue a SHOW TABLES command, then your temporary table would not be listed out in the list. Now, if you will log out of the MySQL session and then you will issue a SELECT command, then you will find no data available in the database. Even your temporary table would also not exist. Dropping Temporary Tables By default, all the temporary tables are deleted by MySQL when your database connection gets terminated. Still if you want to delete them in between, then you do so by issuing DROP TABLE command. Following is the example on dropping a temporary table − mysql> DROP TABLE SalesSummary; mysql> SELECT * FROM SalesSummary; ERROR 1146: Table ”TUTORIALS.SalesSummary” doesn”t exist Print Page Previous Next Advertisements ”;

MySQLi – Data Types ”; Previous Next Properly defining the fields in a table is important to the overall optimization of your database. You should use only the type and size of field you really need to use; don”t define a field as 10 characters wide if you know you”re only going to use 2 characters. These types of fields (or columns) are also referred to as data types, after the type of data you will be storing in those fields. MySQL uses many different data types broken into three categories: numeric, date and time, and string types. Numeric Data Types MySQL uses all the standard ANSI SQL numeric data types, so if you”re coming to MySQL from a different database system, these definitions will look familiar to you. The following list shows the common numeric data types and their descriptions − INT − A normal-sized integer that can be signed or unsigned. If signed, the allowable range is from -2147483648 to 2147483647. If unsigned, the allowable range is from 0 to 4294967295. You can specify a width of up to 11 digits. TINYINT − A very small integer that can be signed or unsigned. If signed, the allowable range is from -128 to 127. If unsigned, the allowable range is from 0 to 255. You can specify a width of up to 4 digits. SMALLINT − A small integer that can be signed or unsigned. If signed, the allowable range is from -32768 to 32767. If unsigned, the allowable range is from 0 to 65535. You can specify a width of up to 5 digits. MEDIUMINT − A medium-sized integer that can be signed or unsigned. If signed, the allowable range is from -8388608 to 8388607. If unsigned, the allowable range is from 0 to 16777215. You can specify a width of up to 9 digits. BIGINT − A large integer that can be signed or unsigned. If signed, the allowable range is from -9223372036854775808 to 9223372036854775807. If unsigned, the allowable range is from 0 to 18446744073709551615. You can specify a width of up to 20 digits. FLOAT(M,D) − A floating-point number that cannot be unsigned. You can define the display length (M) and the number of decimals (D). This is not required and will default to 10,2, where 2 is the number of decimals and 10 is the total number of digits (including decimals). Decimal precision can go to 24 places for a FLOAT. DOUBLE(M,D) − A double precision floating-point number that cannot be unsigned. You can define the display length (M) and the number of decimals (D). This is not required and will default to 16,4, where 4 is the number of decimals. Decimal precision can go to 53 places for a DOUBLE. REAL is a synonym for DOUBLE. DECIMAL(M,D) − An unpacked floating-point number that cannot be unsigned. In unpacked decimals, each decimal corresponds to one byte. Defining the display length (M) and the number of decimals (D) is required. NUMERIC is a synonym for DECIMAL. Date and Time Types The MySQL date and time datatypes are − DATE − A date in YYYY-MM-DD format, between 1000-01-01 and 9999-12-31. For example, December 30th, 1973 would be stored as 1973-12-30. DATETIME − A date and time combination in YYYY-MM-DD HH:MM:SS format, between 1000-01-01 00:00:00 and 9999-12-31 23:59:59. For example, 3:30 in the afternoon on December 30th, 1973 would be stored as 1973-12-30 15:30:00. TIMESTAMP − A timestamp between midnight, January 1, 1970 and sometime in 2037. This looks like the previous DATETIME format, only without the hyphens between numbers; 3:30 in the afternoon on December 30th, 1973 would be stored as 19731230153000 ( YYYYMMDDHHMMSS ). TIME − Stores the time in HH:MM:SS format. YEAR(M) − Stores a year in 2-digit or 4-digit format. If the length is specified as 2 (for example YEAR(2)), YEAR can be 1970 to 2069 (70 to 69). If the length is specified as 4, YEAR can be 1901 to 2155. The default length is 4. String Types Although numeric and date types are fun, most data you”ll store will be in string format. This list describes the common string datatypes in MySQLi. CHAR(M) − A fixed-length string between 1 and 255 characters in length (for example CHAR(5)), right-padded with spaces to the specified length when stored. Defining a length is not required, but the default is 1. VARCHAR(M) − A variable-length string between 1 and 255 characters in length; for example VARCHAR(25). You must define a length when creating a VARCHAR field. BLOB or TEXT − A field with a maximum length of 65535 characters. BLOBs are “Binary Large Objects” and are used to store large amounts of binary data, such as images or other types of files. Fields defined as TEXT also hold large amounts of data; the difference between the two is that sorts and comparisons on stored data are case sensitive on BLOBs and are not case sensitive in TEXT fields. You do not specify a length with BLOB or TEXT. TINYBLOB or TINYTEXT − A BLOB or TEXT column with a maximum length of 255 characters. You do not specify a length with TINYBLOB or TINYTEXT. MEDIUMBLOB or MEDIUMTEXT − A BLOB or TEXT column with a maximum length of 16777215 characters. You do not specify a length with MEDIUMBLOB or MEDIUMTEXT. LONGBLOB or LONGTEXT − A BLOB or TEXT column with a maximum length of 4294967295 characters. You do not specify a length with LONGBLOB or LONGTEXT. ENUM − An enumeration, which is a fancy term for list. When defining an ENUM, you are creating a list of items from which the value must be selected (or it can be NULL). For example, if you wanted your field to contain “A” or “B” or “C”, you would define

MySQLi – Handling NULL Values ”; Previous Next We have seen the SQL SELECT command along with the WHERE clause to fetch data from a MySQL table, but when we try to give a condition, which compares the field or the column value to NULL, it does not work properly. To handle such a situation, MySQL provides three operators − IS NULL − This operator returns true, if the column value is NULL. IS NOT NULL − This operator returns true, if the column value is not NULL. <=> − This operator compares values, which (unlike the = operator) is true even for two NULL values. The conditions involving NULL are special. You cannot use = NULL or != NULL to look for NULL values in columns. Such comparisons always fail because it is impossible to tell whether they are true or not. Sometimes, even NULL = NULL fails. To look for columns that are or are not NULL, use IS NULL or IS NOT NULL. Using NULL values at the Command Prompt Assume that there is a table called tcount_tbl in the TUTORIALS database and it contains two columns namely tutorial_author and tutorial_count, where a NULL tutorial_count indicates that the value is unknown. Example Try the following examples − root@host# mysql -u root -p password; Enter password:******* mysql> use TUTORIALS; Database changed mysql> create table tcount_tbl → ( → tutorial_author varchar(40) NOT NULL, → tutorial_count INT → ); Query OK, 0 rows affected (0.05 sec) mysql> INSERT INTO tcount_tbl → (tutorial_author, tutorial_count) values (”mahran”, 20); mysql> INSERT INTO tcount_tbl → (tutorial_author, tutorial_count) values (”mahnaz”, NULL); mysql> INSERT INTO tcount_tbl → (tutorial_author, tutorial_count) values (”Jen”, NULL); mysql> INSERT INTO tcount_tbl → (tutorial_author, tutorial_count) values (”Gill”, 20); mysql> SELECT * from tcount_tbl; +—————–+—————-+ | tutorial_author | tutorial_count | +—————–+—————-+ | mahran | 20 | | mahnaz | NULL | | Jen | NULL | | Gill | 20 | +—————–+—————-+ 4 rows in set (0.00 sec) mysql> You can see that = and != do not work with NULL values as follows − mysql> SELECT * FROM tcount_tbl WHERE tutorial_count = NULL; Empty set (0.00 sec) mysql> SELECT * FROM tcount_tbl WHERE tutorial_count != NULL; Empty set (0.01 sec) To find the records where the tutorial_count column is or is not NULL, the queries should be written as shown in the following program. mysql> SELECT * FROM tcount_tbl → WHERE tutorial_count IS NULL; +—————–+—————-+ | tutorial_author | tutorial_count | +—————–+—————-+ | mahnaz | NULL | | Jen | NULL | +—————–+—————-+ 2 rows in set (0.00 sec) mysql> SELECT * from tcount_tbl → WHERE tutorial_count IS NOT NULL; +—————–+—————-+ | tutorial_author | tutorial_count | +—————–+—————-+ | mahran | 20 | | Gill | 20 | +—————–+—————-+ 2 rows in set (0.00 sec) Handling NULL Values in a PHP Script You can use the if…else condition to prepare a query based on the NULL value. The following example takes the tutorial_count from outside and then compares it with the value available in the table. Example Copy and paste the following example as mysql_example.php − <html> <head> <title>Handling NULL</title> </head> <body> <?php $dbhost = ”localhost”; $dbuser = ”root”; $dbpass = ”root@123”; $dbname = ”TUTORIALS”; $mysqli = new mysqli($dbhost, $dbuser, $dbpass, $dbname); $tutorial_count = null; if($mysqli→connect_errno ) { printf(“Connect failed: %s<br />”, $mysqli→connect_error); exit(); } printf(”Connected successfully.<br />”); if( isset($tutorial_count )) { $sql = ”SELECT tutorial_author, tutorial_count FROM tcount_tbl WHERE tutorial_count = ” + $tutorial_count; } else { $sql = ”SELECT tutorial_author, tutorial_count FROM tcount_tbl WHERE tutorial_count IS NULL”; } $result = $mysqli→query($sql); if ($result→num_rows > 0) { while($row = $result→fetch_assoc()) { printf(“Author: %s, Count: %d <br />”, $row[“tutorial_author”], $row[“tutorial_count”]); } } else { printf(”No record found.<br />”); } $mysqli→close(); ?> </body> </html> Output Access the mysql_example.php deployed on apache web server and verify the output. Connected successfully. No record found. Print Page Previous Next Advertisements ”;

MySQLi – Like Clause ”; Previous Next We have seen the SQL SELECT command to fetch data from the MySQL table. We can also use a conditional clause called as the WHERE clause to select the required records. A WHERE clause with the ‘equal to’ sign (=) works fine where we want to do an exact match. Like if “tutorial_author = ”Sanjay””. But there may be a requirement where we want to filter out all the results where tutorial_author name should contain “jay”. This can be handled using SQL LIKE Clause along with the WHERE clause. If the SQL LIKE clause is used along with the % character, then it will work like a meta character (*) as in UNIX, while listing out all the files or directories at the command prompt. Without a % character, the LIKE clause is very same as the equal to sign along with the WHERE clause. Syntax The following code block has a generic SQL syntax of the SELECT command along with the LIKE clause to fetch data from a MySQL table. SELECT field1, field2,…fieldN table_name1, table_name2… WHERE field1 LIKE condition1 [AND [OR]] filed2 = ”somevalue” You can specify any condition using the WHERE clause. You can use the LIKE clause along with the WHERE clause. You can use the LIKE clause in place of the equals to sign. When LIKE is used along with % sign then it will work like a meta character search. You can specify more than one condition using AND or OR operators. A WHERE…LIKE clause can be used along with DELETE or UPDATE SQL command also to specify a condition. Using the LIKE clause at the Command Prompt This will use the SQL SELECT command with the WHERE…LIKE clause to fetch the selected data from the MySQL table – tutorials_tbl. Example The following example will return all the records from the tutorials_tbl table for which the author name ends with jay − root@host# mysql -u root -p password; Enter password:******* mysql> use TUTORIALS; Database changed mysql> SELECT * from tutorials_tbl → WHERE tutorial_author LIKE ”%jay”; +————-+—————-+—————–+—————–+ | tutorial_id | tutorial_title | tutorial_author | submission_date | +————-+—————-+—————–+—————–+ | 3 | JAVA Tutorial | Sanjay | 2007-05-21 | +————-+—————-+—————–+—————–+ 1 rows in set (0.01 sec) mysql> Using LIKE clause inside PHP Script PHP uses mysqli query() or mysql_query() function to select records in a MySQL table using Like clause. This function takes two parameters and returns TRUE on success or FALSE on failure. Syntax $mysqli→query($sql,$resultmode) Sr.No. Parameter & Description 1 $sql Required – SQL query to select records in a MySQL table using Like Clause. 2 $resultmode Optional – Either the constant MYSQLI_USE_RESULT or MYSQLI_STORE_RESULT depending on the desired behavior. By default, MYSQLI_STORE_RESULT is used. Example Try the following example to select a record using like clause in a table − Copy and paste the following example as mysql_example.php − <html> <head> <title>Using Like Clause</title> </head> <body> <?php $dbhost = ”localhost”; $dbuser = ”root”; $dbpass = ”root@123”; $dbname = ”TUTORIALS”; $mysqli = new mysqli($dbhost, $dbuser, $dbpass, $dbname); if($mysqli→connect_errno ) { printf(“Connect failed: %s<br />”, $mysqli→connect_error); exit(); } printf(”Connected successfully.<br />”); $sql = ”SELECT tutorial_id, tutorial_title, tutorial_author, submission_date FROM tutorials_tbl where tutorial_author like “Mah%””; $result = $mysqli→query($sql); if ($result→num_rows > 0) { while($row = $result→fetch_assoc()) { printf(“Id: %s, Title: %s, Author: %s, Date: %d <br />”, $row[“tutorial_id”], $row[“tutorial_title”], $row[“tutorial_author”], $row[“submission_date”]); } } else { printf(”No record found.<br />”); } mysqli_free_result($result); $mysqli→close(); ?> </body> </html> Output Access the mysql_example.php deployed on apache web server and verify the output. Here we”ve entered multiple records in the table before running the select script. Connected successfully. Id: 1, Title: MySQL Tutorial, Author: Mahesh, Date: 2021 Id: 2, Title: HTML Tutorial, Author: Mahesh, Date: 2021 Id: 3, Title: PHP Tutorial, Author: Mahesh, Date: 2021 Print Page Previous Next Advertisements ”;

MySQLi – Database Info ”; Previous Next Obtaining and Using MySQL Metadata There are three types of information, which you would like to have from MySQL. Information about the result of queries − This includes the number of records affected by any SELECT, UPDATE or DELETE statement. Information about the tables and databases − This includes information pertaining to the structure of the tables and the databases. Information about the MySQL server − This includes the status of the database server, version number, etc. It is very easy to get all this information at the MySQL prompt, but while using PERL or PHP APIs, we need to call various APIs explicitly to obtain all this information. Obtaining the Number of Rows Affected by a Query Let is now see how to obtain this information. PERL Example In DBI scripts, the affected row count is returned by the do( ) or by the execute( ) command, depending on how you execute the query. # Method 1 # execute $query using do( ) my $count = $dbh→do ($query); # report 0 rows if an error occurred printf “%d rows were affectedn”, (defined ($count) ? $count : 0); # Method 2 # execute query using prepare( ) plus execute( ) my $sth = $dbh→prepare ($query); my $count = $sth→execute ( ); printf “%d rows were affectedn”, (defined ($count) ? $count : 0); PHP Example In PHP, invoke the mysql_affected_rows( ) function to find out how many rows a query changed. $result_id = mysql_query ($query, $conn_id); # report 0 rows if the query failed $count = ($result_id ? mysql_affected_rows ($conn_id) : 0); print (“$count rows were affectedn”); Listing Tables and Databases It is very easy to list down all the databases and the tables available with a database server. Your result may be null if you don”t have the sufficient privileges. Apart from the method which is shown in the following code block, you can use SHOW TABLES or SHOW DATABASES queries to get the list of tables or databases either in PHP or in PERL. PERL Example # Get all the tables available in current database. my @tables = $dbh→tables ( ); foreach $table (@tables ){ print “Table Name $tablen”; } PHP Example Try the following example to get database info − Copy and paste the following example as mysql_example.php − <html> <head> <title>Getting MySQL Database Info</title> </head> <body> <?php $dbhost = ”localhost”; $dbuser = ”root”; $dbpass = ”root@123”; $dbname = ”TUTORIALS”; $mysqli = new mysqli($dbhost, $dbuser, $dbpass, $dbname); $tutorial_count = null; if($mysqli→connect_errno ) { printf(“Connect failed: %s<br />”, $mysqli→connect_error); exit(); } printf(”Connected successfully.<br />”); if ($result = mysqli_query($mysqli, “SELECT DATABASE()”)) { $row = mysqli_fetch_row($result); printf(“Default database is %s<br />”, $row[0]); mysqli_free_result($result); } $mysqli→close(); ?> </body> </html> Output Access the mysql_example.php deployed on apache web server and verify the output. Connected successfully. Default database is tutorials Getting Server Metadata There are a few important commands in MySQL which can be executed either at the MySQL prompt or by using any script like PHP to get various important information about the database server. Sr.No. Command & Description 1 SELECT VERSION( ) Server version string 2 SELECT DATABASE( ) Current database name (empty if none) 3 SELECT USER( ) Current username 4 SHOW STATUS Server status indicators 5 SHOW VARIABLES Server configuration variables Print Page Previous Next Advertisements ”;

MySQLi – Delete Query ”; Previous Next If you want to delete a record from any MySQL table, then you can use the SQL command DELETE FROM. You can use this command at the mysql> prompt as well as in any script like PHP. Syntax The following code block has a generic SQL syntax of the DELETE command to delete data from a MySQL table. DELETE FROM table_name [WHERE Clause] If the WHERE clause is not specified, then all the records will be deleted from the given MySQL table. You can specify any condition using the WHERE clause. You can delete records in a single table at a time. The WHERE clause is very useful when you want to delete selected rows in a table. Deleting Data from the Command Prompt This will use the SQL DELETE command with the WHERE clause to delete selected data into the MySQL table – tutorials_tbl. Example The following example will delete a record from the tutorial_tbl whose tutorial_id is 3. root@host# mysql -u root -p password; Enter password:******* mysql> use TUTORIALS; Database changed mysql> DELETE FROM tutorials_tbl WHERE tutorial_id=3; Query OK, 1 row affected (0.23 sec) mysql> Deleting Data Using a PHP Script PHP uses mysqli query() or mysql_query() function to delete records in a MySQL table. This function takes two parameters and returns TRUE on success or FALSE on failure. Syntax $mysqli→query($sql,$resultmode) Sr.No. Parameter & Description 1 $sql Required – SQL query to delete records in a MySQL table. 2 $resultmode Optional – Either the constant MYSQLI_USE_RESULT or MYSQLI_STORE_RESULT depending on the desired behavior. By default, MYSQLI_STORE_RESULT is used. Example Try the following example to delete a record in a table − Copy and paste the following example as mysql_example.php − <html> <head> <title>Deleting MySQL Table record</title> </head> <body> <?php $dbhost = ”localhost”; $dbuser = ”root”; $dbpass = ”root@123”; $dbname = ”TUTORIALS”; $mysqli = new mysqli($dbhost, $dbuser, $dbpass, $dbname); if($mysqli→connect_errno ) { printf(“Connect failed: %s<br />”, $mysqli→connect_error); exit(); } printf(”Connected successfully.<br />”); if ($mysqli→query(”DELETE FROM tutorials_tbl where tutorial_id = 4”)) { printf(“Table tutorials_tbl record deleted successfully.<br />”); } if ($mysqli→errno) { printf(“Could not delete record from table: %s<br />”, $mysqli→error); } $sql = “SELECT tutorial_id, tutorial_title, tutorial_author, submission_date FROM tutorials_tbl”; $result = $mysqli→query($sql); if ($result→num_rows > 0) { while($row = $result→fetch_assoc()) { printf(“Id: %s, Title: %s, Author: %s, Date: %d <br />”, $row[“tutorial_id”], $row[“tutorial_title”], $row[“tutorial_author”], $row[“submission_date”]); } } else { printf(”No record found.<br />”); } mysqli_free_result($result); $mysqli→close(); ?> </body> </html> Output Access the mysql_example.php deployed on apache web server and verify the output. Here we”ve entered multiple records in the table before running the select script. Connected successfully. Table tutorials_tbl record deleted successfully. Id: 1, Title: MySQL Tutorial, Author: Mahesh, Date: 2021 Id: 2, Title: HTML Tutorial, Author: Mahesh, Date: 2021 Id: 3, Title: PHP Tutorial, Author: Mahesh, Date: 2021 Id: 5, Title: Apache Tutorial, Author: Suresh, Date: 2021 Print Page Previous Next Advertisements ”;

MySQLi – Select Query ”; Previous Next The SQL SELECT command is used to fetch data from the MySQL database. You can use this command at mysql> prompt as well as in any script like PHP. Syntax Here is generic SQL syntax of SELECT command to fetch data from the MySQL table − SELECT field1, field2,…fieldN FROM table_name1, table_name2… [WHERE Clause] [OFFSET M ][LIMIT N] You can use one or more tables separated by comma to include various conditions using a WHERE clause, but the WHERE clause is an optional part of the SELECT command. You can fetch one or more fields in a single SELECT command. You can specify star (*) in place of fields. In this case, SELECT will return all the fields. You can specify any condition using the WHERE clause. You can specify an offset using OFFSET from where SELECT will start returning records. By default, the offset starts at zero. You can limit the number of returns using the LIMIT attribute. Fetching Data from a Command Prompt This will use SQL SELECT command to fetch data from the MySQL table tutorials_tbl. Example The following example will return all the records from the tutorials_tbl table − root@host# mysql -u root -p password; Enter password:******* mysql> use TUTORIALS; Database changed mysql> SELECT * from tutorials_tbl +————-+—————-+—————–+—————–+ | tutorial_id | tutorial_title | tutorial_author | submission_date | +————-+—————-+—————–+—————–+ | 1 | Learn PHP | John Poul | 2007-05-21 | | 2 | Learn MySQL | Abdul S | 2007-05-21 | | 3 | JAVA Tutorial | Sanjay | 2007-05-21 | +————-+—————-+—————–+—————–+ 3 rows in set (0.01 sec) mysql> Fetching Data Using a PHP Script PHP uses mysqli query() or mysql_query() function to select records from a MySQL table. This function takes two parameters and returns TRUE on success or FALSE on failure. Syntax $mysqli→query($sql,$resultmode) Sr.No. Parameter & Description 1 $sql Required – SQL query to select records from a MySQL table. 2 $resultmode Optional – Either the constant MYSQLI_USE_RESULT or MYSQLI_STORE_RESULT depending on the desired behavior. By default, MYSQLI_STORE_RESULT is used. Example Try the following example to select a record from a table − Copy and paste the following example as mysql_example.php − <html> <head> <title>Creating MySQL Table</title> </head> <body> <?php $dbhost = ”localhost”; $dbuser = ”root”; $dbpass = ”root@123”; $dbname = ”TUTORIALS”; $mysqli = new mysqli($dbhost, $dbuser, $dbpass, $dbname); if($mysqli→connect_errno ) { printf(“Connect failed: %s<br />”, $mysqli→connect_error); exit(); } printf(”Connected successfully.<br />”); $sql = “SELECT tutorial_id, tutorial_title, tutorial_author, submission_date FROM tutorials_tbl”; $result = $mysqli->query($sql); if ($result->num_rows > 0) { while($row = $result->fetch_assoc()) { printf(“Id: %s, Title: %s, Author: %s, Date: %d <br />”, $row[“tutorial_id”], $row[“tutorial_title”], $row[“tutorial_author”], $row[“submission_date”]); } } else { printf(”No record found.<br />”); } mysqli_free_result($result); $mysqli→close(); ?> </body> </html> Output Access the mysql_example.php deployed on apache web server and verify the output. Here we”ve entered multiple records in the table before running the select script. Connected successfully. Id: 1, Title: MySQL Tutorial, Author: Mahesh, Date: 2021 Id: 2, Title: HTML Tutorial, Author: Mahesh, Date: 2021 Id: 3, Title: PHP Tutorial, Author: Mahesh, Date: 2021 Id: 4, Title: Java Tutorial, Author: Mahesh, Date: 2021 Id: 5, Title: Apache Tutorial, Author: Suresh, Date: 2021 Print Page Previous Next Advertisements ”;

MySQLi – Administration ”; Previous Next Running and Shutting down MySQL Server First check if your MySQL server is running or not. You can use the following command to check it − ps -ef | grep mysqld If your MySql is running, then you will see mysqld process listed out in your result. If server is not running, then you can start it by using the following command − root@host# cd /usr/bin ./safe_mysqld & Now, if you want to shut down an already running MySQL server, then you can do it by using the following command − root@host# cd /usr/bin ./mysqladmin -u root -p shutdown Enter password: ****** Setting Up a MySQL User Account For adding a new user to MySQL, you just need to add a new entry to the user table in the database mysql. The following program is an example of adding a new user guest with SELECT, INSERT and UPDATE privileges with the password guest123; the SQL query is − root@host# mysql -u root -p Enter password:******* mysql> use mysql; Database changed mysql> INSERT INTO user (host, user, password, select_priv, insert_priv, update_priv) VALUES (”localhost”, ”guest”, PASSWORD(”guest123”), ”Y”, ”Y”, ”Y”); Query OK, 1 row affected (0.20 sec) mysql> FLUSH PRIVILEGES; Query OK, 1 row affected (0.01 sec) mysql> SELECT host, user, password FROM user WHERE user = ”guest”; +———–+———+——————+ | host | user | password | +———–+———+——————+ | localhost | guest | 6f8c114b58f2ce9e | +———–+———+——————+ 1 row in set (0.00 sec) When adding a new user, remember to encrypt the new password using PASSWORD() function provided by MySQL. As you can see in the above example, the password mypass is encrypted to 6f8c114b58f2ce9e. Notice the FLUSH PRIVILEGES statement. This tells the server to reload the grant tables. If you don”t use it, then you won”t be able to connect to MySQL using the new user account at least until the server is rebooted. You can also specify other privileges to a new user by setting the values of following columns in user table to ”Y” when executing the INSERT query or you can update them later using UPDATE query. Select_priv Insert_priv Update_priv Delete_priv Create_priv Drop_priv Reload_priv Shutdown_priv Process_priv File_priv Grant_priv References_priv Index_priv Alter_priv Another way of adding user account is by using GRANT SQL command. The following example will add user zara with password zara123 for a particular database, which is named as TUTORIALS. root@host# mysql -u root -p password; Enter password:******* mysql> use mysql; Database changed mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP → ON TUTORIALS.* → TO ”zara”@”localhost” → IDENTIFIED BY ”zara123”; This will also create an entry in the MySQL database table called as user. NOTE − MySQL does not terminate a command until you give a semi colon (;) at the end of the SQL command. The /etc/my.cnf File Configuration In most of the cases, you should not touch this file. By default, it will have the following entries − [mysqld] datadir = /var/lib/mysql socket = /var/lib/mysql/mysql.sock [mysql.server] user = mysql basedir = /var/lib [safe_mysqld] err-log = /var/log/mysqld.log pid-file = /var/run/mysqld/mysqld.pid Here, you can specify a different directory for the error log, otherwise you should not change any entry in this table. Administrative MySQL Command Here is the list of the important MySQL commands, which you will use time to time to work with MySQL database − USE Databasename − This will be used to select a database in the MySQL workarea. SHOW DATABASES − Lists out the databases that are accessible by the MySQL DBMS. SHOW TABLES − Shows the tables in the database once a database has been selected with the use command. SHOW COLUMNS FROM tablename: Shows the attributes, types of attributes, key information, whether NULL is permitted, defaults, and other information for a table. SHOW INDEX FROM tablename − Presents the details of all indexes on the table, including the PRIMARY KEY. SHOW TABLE STATUS LIKE tablenameG − Reports details of the MySQL DBMS performance and statistics. Print Page Previous Next Advertisements ”;

MySQLi – Installation ”; Previous Next Downloading MySQL The MySQLi extension is designed to work with MySQL version 4.1.13 or newer, So have to download MySQL. All downloads for MySQL are located at MySQL Downloads. Pick the latest version number for MySQL Community Server you want and, as exactly as possible, the platform you want. Installing MySQL on Linux/UNIX The recommended way to install MySQL on a Linux system is via RPM. MySQL AB makes the following RPMs available for download on its web site − MySQL − The MySQL database server, which manages databases and tables, controls user access, and processes SQL queries. MySQL-client − MySQL client programs, which make it possible to connect to and interact with the server. MySQL-devel − Libraries and header files that come in handy when compiling other programs that use MySQL. MySQL-shared − Shared libraries for the MySQL client. MySQL-bench − Benchmark and performance testing tools for the MySQL database server. The MySQL RPMs listed here are all built on a SuSE Linux system, but they”ll usually work on other Linux variants with no difficulty. Now, follow the following steps to proceed for installation − Login to the system using root user. Switch to the directory containing the RPMs − Install the MySQL database server by executing the following command. Remember to replace the filename in italics with the file name of your RPM. [root@host]# rpm -i MySQL-5.0.9-0.i386.rpm Above command takes care of installing MySQL server, creating a user of MySQL, creating necessary configuration and starting MySQL server automatically. You can find all the MySQL related binaries in /usr/bin and /usr/sbin. All the tables and databases will be created in /var/lib/mysql directory. This is optional but recommended step to install the remaining RPMs in the same manner − [root@host]# rpm -i MySQL-client-5.0.9-0.i386.rpm [root@host]# rpm -i MySQL-devel-5.0.9-0.i386.rpm [root@host]# rpm -i MySQL-shared-5.0.9-0.i386.rpm [root@host]# rpm -i MySQL-bench-5.0.9-0.i386.rpm Installing MySQL on Windows Default installation on any version of Windows is now much easier than it used to be, as MySQL now comes neatly packaged with an installer. Simply download the installer package, unzip it anywhere, and run setup.exe. Default installer setup.exe will walk you through the trivial process and by default will install everything under C:mysql. Test the server by firing it up from the command prompt the first time. Go to the location of the mysqld server which is probably C:mysqlbin, and type − mysqld.exe –console NOTE − If you are on NT, then you will have to use mysqld-nt.exe instead of mysqld.exe If all went well, you will see some messages about startup and InnoDB. If not, you may have a permissions issue. Make sure that the directory that holds your data is accessible to whatever user (probably mysql) the database processes run under. MySQL will not add itself to the start menu, and there is no particularly nice GUI way to stop the server either. Therefore, if you tend to start the server by double clicking the mysqld executable, you should remember to halt the process by hand by using mysqladmin, Task List, Task Manager, or other Windows-specific means. Verifying MySQL Installation After MySQL has been successfully installed, the base tables have been initialized, and the server has been started, you can verify that all is working as it should via some simple tests. Use the mysqladmin Utility to Obtain Server Status Use mysqladmin binary to check server version. This binary would be available in /usr/bin on linux and in C:mysqlbin on windows. [root@host]# mysqladmin –version It will produce the following result on Linux. It may vary depending on your installation − mysqladmin Ver 8.23 Distrib 5.0.9-0, for redhat-linux-gnu on i386 If you do not get such message, then there may be some problem in your installation and you would need some help to fix it. Execute simple SQL commands using MySQL Client You can connect to your MySQL server by using MySQL client using mysql command. At this moment, you do not need to give any password as by default it will be set to blank. So just use following command [root@host]# mysql It should be rewarded with a mysql> prompt. Now, you are connected to the MySQL server and you can execute all the SQL command at mysql> prompt as follows − mysql> SHOW DATABASES; +———-+ | Database | +———-+ | mysql | | test | +———-+ 2 rows in set (0.13 sec) Post-installation Steps MySQL ships with a blank password for the root MySQL user. As soon as you have successfully installed the database and client, you need to set a root password as follows − [root@host]# mysqladmin -u root password “new_password”; Now to make a connection to your MySQL server, you would have to use the following command − [root@host]# mysql -u root -p Enter password:******* UNIX users will also want to put your MySQL directory in your PATH, so you won”t have to keep typing out the full path every time you want to use the command-line client. For bash, it would be something like − export PATH = $PATH:/usr/bin:/usr/sbin Running MySQL at boot time If you want to run MySQL server at boot time, then make sure you have following entry in /etc/rc.local file. /etc/init.d/mysqld start Also,you should have mysqld binary in /etc/init.d/ directory. Print Page Previous Next Advertisements ”;