MySQL – Reset Auto-Increment
Table of content
- AUTO-INCREMENT in MySQL
- The MySQL RESET Auto-Increment
- RESET using ALTER TABLE Statement
- RESET using TRUNCATE TABLE Statement
- Resetting Auto-Increment Using Client Program
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Most of the tables in MySQL use sequential values to represent records, like serial numbers. Instead of manually inserting each value one by one, MySQL uses the “AUTO_INCREMENT” to handle this automatically.
AUTO-INCREMENT in MySQL
AUTO_INCREMENT in MySQL is used to generate unique numbers in ascending order automatically as you add new records to a table. It is very useful for applications that require each row to have a distinct value.
When you define a column as an AUTO_INCREMENT column, MySQL takes care of the rest. It starts with the value 1 and increments it by 1 for each new record you insert, creating a sequence of unique numbers for your table.
Example
The following example demonstrates the usage of AUTO_INCREMENT on a column in database table. Here, we are creating a table named ”insect” with AUTO_INCREMENT applied to the ”id” column.
CREATE TABLE insect ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, PRIMARY KEY (id), name VARCHAR(30) NOT NULL, date DATE NOT NULL, origin VARCHAR(30) NOT NULL );
Now, you don”t need to manually specify values for the ”id” column when inserting records. Instead, MySQL handles it for you, starting with 1 and incrementing by 1 for each new record. To insert values in other columns of the table, use the following query −
INSERT INTO insect (name,date,origin) VALUES (''housefly'',''2001-09-10'',''kitchen''), (''millipede'',''2001-09-10'',''driveway''), (''grasshopper'',''2001-09-10'',''front yard'');
The insect table displayed is as follows. Here, we can see that the ”id” column values are automatically generated by MySQL −
id | name | date | origin |
---|---|---|---|
1 | housefly | 2001-09-10 | kitchen |
2 | millipede | 2001-09-10 | driveway |
3 | grasshopper | 2001-09-10 | front yard |
The MySQL RESET Auto-Increment
The default AUTO_INCREMENT values on a table start from 1, i.e., the values being inserted usually start from 1. However, MySQL also has a provision to reset these AUTO-INCREMENT values to another number, enabling the sequence to start inserting from the specified reset value.
You can reset the AUTO_INCREMENT value in three ways: using ALTER TABLE, TRUNCATE TABLE, or dropping and recreating the table.
RESET using ALTER TABLE Statement
The ALTER TABLE statement in MySQL is used to update a table or make any alterations in it. Hence, using this statement to reset an AUTO_INCREMENT value is perfectly valid choice.
Syntax
Following is the syntax to reset autoincrement using ALTER TABLE −
ALTER TABLE table_name AUTO_INCREMENT = new_value;
Example
In this example, we are using the ALTER TABLE statement to reset the AUTO_INCREMENT value to 5. Note that the new AUTO_INCREMENT value be greater than the number of records already present in the table −
ALTER TABLE insect AUTO_INCREMENT = 5;
Following is the output obtained −
Query OK, 0 rows affected (0.01 sec) Records: 0 Duplicates: 0 Warnings: 0
Now, let us insert another value into the table ”insect” created above and check the new result-set, using the following queries −
INSERT INTO insect (name,date,origin) VALUES (''spider'', ''2000-12-12'', ''bathroom''), (''larva'', ''2012-01-10'', ''garden'');
We get the result as shown below −
Query OK, 2 row affected (0.01 sec) Records: 2 Duplicates: 0 Warnings: 0
To verify whether the new records you inserted will start with the AUTO_INCREMENT value set to 5, use the following SELECT query −
SELECT * FROM insect;
The table obtained is as shown below −
id | name | date | origin |
---|---|---|---|
1 | housefly | 2001-09-10 | kitchen |
2 | millipede | 2001-09-10 | driveway |
3 | grasshopper | 2001-09-10 | front yard |
5 | spider | 2000-12-12 | bathroom |
6 | larva | 2012-01-10 | garden |
RESET using TRUNCATE TABLE Statement
Another way to reset auto-incrementing column to the default value is by using the TRUNCATE TABLE command.
This will delete the existing data of a table, and when you insert new records, the AUTO_INCREMENT column starts from the beginning (usually 1).
Example
Following is an example to reset the AUTO_INCREMENT value to default, i.e. ”0”. For that, firstly truncate the ”insect” table created above using the TRUNCATE TABLE Command as follows −
TRUNCATE TABLE insect;
The output obtained is as follows −
Query OK, 0 rows affected (0.04 sec)
To verify whether the records of the table is deleted, use the following SELECT query −
SELECT * FROM insect;
The result produced is as follows −
Empty set (0.00 sec)
Now, insert values again using the following INSERT statement.
INSERT INTO insect (name,date,origin) VALUES (''housefly'',''2001-09-10'',''kitchen''), (''millipede'',''2001-09-10'',''driveway''), (''grasshopper'',''2001-09-10'',''front yard''), (''spider'', ''2000-12-12'', ''bathroom'');
After executing the above code, we get the following output −
Query OK, 4 rows affected (0.00 sec) Records: 4 Duplicates: 0 Warnings: 0
You can verify whether the records in the table have been reset using the following SELECT query −
SELECT * FROM insect;
The table displayed is as follows −
id | name | date | origin |
---|---|---|---|
1 | housefly | 2001-09-10 | kitchen |
2 | millipede | 2001-09-10 | driveway |
3 | grasshopper | 2001-09-10 | front yard |
4 | spider | 2000-12-12 | bathroom |
Resetting Auto-Increment Using Client Program
We can also reset auto-increment using client program.
Syntax
To reset auto-increment through a PHP program, we need to execute the “ALTER TABLE” statement using the mysqli function query() as follows −
$sql = "ALTER TABLE INSECT AUTO_INCREMENT = 5"; $mysqli->query($sql);
To reset auto-increment through a JavaScript program, we need to execute the “ALTER TABLE” statement using the query() function of mysql2 library as follows −
sql = "ALTER TABLE insect AUTO_INCREMENT = 5"; con.query(sql)
To reset auto-increment through a Java program, we need to execute the “ALTER TABLE” statement using the JDBC function execute() as follows −
String sql = "ALTER TABLE insect AUTO_INCREMENT = 5"; statement.execute(sql);
To reset auto-increment through a Python program, we need to execute the “ALTER TABLE” statement using the execute() function of the MySQL Connector/Python as follows −
reset_auto_inc_query = "ALTER TABLE insect AUTO_INCREMENT = 5" cursorObj.execute(reset_auto_inc_query)
Example
Following are the programs −
$dbhost = ''localhost''; $dbuser = ''root''; $dbpass = ''password''; $db = ''TUTORIALS''; $mysqli = new mysqli($dbhost, $dbuser, $dbpass, $db); if ($mysqli->connect_errno) { printf("Connect failed: %s
", $mysqli->connect_error); exit(); } //printf(''Connected successfully.
''); //lets create a table $sql = "CREATE TABLE insect (id INT UNSIGNED NOT NULL AUTO_INCREMENT,PRIMARY KEY (id),name VARCHAR(30) NOT NULL,date DATE NOT NULL,origin VARCHAR(30) NOT NULL)"; if($mysqli->query($sql)){ printf("Insect table created successfully....!n"); } //now lets insert some records $sql = "INSERT INTO insect (name,date,origin) VALUES (''housefly'',''2001-09-10'',''kitchen''), (''millipede'',''2001-09-10'',''driveway''), (''grasshopper'',''2001-09-10'',''front yard'')"; if($mysqli->query($sql)){ printf("Records inserted successfully....!n"); } //display table records $sql = "SELECT * FROM INSECT"; if($result = $mysqli->query($sql)){ printf("Table records: n"); while($row = mysqli_fetch_array($result)){ printf("Id: %d, Name: %s, Date: %s, Origin: %s", $row[''id''], $row[''name''], $row[''date''], $row[''origin'']); printf("n"); } } //lets reset the autoincrement using alter table statement... $sql = "ALTER TABLE INSECT AUTO_INCREMENT = 5"; if($mysqli->query($sql)){ printf("Auto_increment reset successfully...!n"); } //now lets insert some more records.. $sql = "INSERT INTO insect (name,date,origin) VALUES (''spider'', ''2000-12-12'', ''bathroom''), (''larva'', ''2012-01-10'', ''garden'')"; $mysqli->query($sql); $sql = "SELECT * FROM INSECT"; if($result = $mysqli->query($sql)){ printf("Table records(after resetting autoincrement): n"); while($row = mysqli_fetch_array($result)){ printf("Id: %d, Name: %s, Date: %s, Origin: %s", $row[''id''], $row[''name''], $row[''date''], $row[''origin'']); printf("n"); } } if($mysqli->error){ printf("Error message: ", $mysqli->error); } $mysqli->close();
Output
The output obtained is as shown below −
Insect table created successfully....! Records inserted successfully....! Table records: Id: 1, Name: housefly, Date: 2001-09-10, Origin: kitchen Id: 2, Name: millipede, Date: 2001-09-10, Origin: driveway Id: 3, Name: grasshopper, Date: 2001-09-10, Origin: front yard Auto_increment reset successfully...! Table records(after resetting autoincrement): Id: 1, Name: housefly, Date: 2001-09-10, Origin: kitchen Id: 2, Name: millipede, Date: 2001-09-10, Origin: driveway Id: 3, Name: grasshopper, Date: 2001-09-10, Origin: front yard Id: 5, Name: spider, Date: 2000-12-12, Origin: bathroom Id: 6, Name: larva, Date: 2012-01-10, Origin: garden
var mysql = require(''mysql2''); var con = mysql.createConnection({ host: "localhost", user: "root", password: "Nr5a0204@123" }); // Connecting to MySQL con.connect(function (err) { if (err) throw err; console.log("Connected!"); console.log("--------------------------"); // Create a new database sql = "Create Database TUTORIALS"; con.query(sql); sql = "USE TUTORIALS"; con.query(sql); sql = "CREATE TABLE insect (id INT UNSIGNED NOT NULL AUTO_INCREMENT,PRIMARY KEY (id),name VARCHAR(30) NOT NULL,date DATE NOT NULL,origin VARCHAR(30) NOT NULL);" con.query(sql); sql = "INSERT INTO insect (name,date,origin) VALUES (''housefly'',''2001-09-10'',''kitchen''),(''millipede'',''2001-09-10'',''driveway''),(''grasshopper'',''2001-09-10'',''front yard'');" con.query(sql); sql = "SELECT * FROM insect;" con.query(sql, function(err, result){ if (err) throw err console.log("**Records of INSECT Table:**"); console.log(result); console.log("--------------------------"); }); sql = "ALTER TABLE insect AUTO_INCREMENT = 5"; con.query(sql); sql = "INSERT INTO insect (name,date,origin) VALUES (''spider'', ''2000-12-12'', ''bathroom''), (''larva'', ''2012-01-10'', ''garden'');" con.query(sql); sql = "SELECT * FROM insect;" con.query(sql, function(err, result){ console.log("**Records after modifying the AUTO_INCREMENT to 5:**"); if (err) throw err console.log(result); }); });
Output
The output obtained is as shown below −
Connected! -------------------------- **Records of INSECT Table:** [ {id: 1,name: ''housefly'',date: 2001-09-09T18:30:00.000Z,origin: ''kitchen''}, {id: 2,name: ''millipede'',date: 2001-09-09T18:30:00.000Z,origin: ''driveway''}, {id: 3,name: ''grasshopper'',date: 2001-09-09T18:30:00.000Z,origin: ''front yard''} ] -------------------------- **Records after modifying the AUTO_INCREMENT to 5:** [ {id: 1,name: ''housefly'',date: 2001-09-09T18:30:00.000Z,origin: ''kitchen''}, {id: 2,name: ''millipede'',date: 2001-09-09T18:30:00.000Z,origin: ''driveway''}, {id: 3,name: ''grasshopper'',date: 2001-09-09T18:30:00.000Z,origin: ''front yard''}, {id: 5,name: ''spider'',date: 2000-12-11T18:30:00.000Z,origin: ''bathroom''}, {id: 6,name: ''larva'',date: 2012-01-09T18:30:00.000Z,origin: ''garden''} ]
import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; public class ResetAutoIncrement { public static void main(String[] args) { String url = "jdbc:mysql://localhost:3306/TUTORIALS"; String user = "root"; String password = "password"; ResultSet rs; try { Class.forName("com.mysql.cj.jdbc.Driver"); Connection con = DriverManager.getConnection(url, user, password); Statement st = con.createStatement(); //System.out.println("Database connected successfully...!"); String sql = "CREATE TABLE insect (id INT UNSIGNED NOT NULL AUTO_INCREMENT,PRIMARY KEY (id),name VARCHAR(30) NOT NULL,date DATE NOT NULL,origin VARCHAR(30) NOT NULL)"; st.execute(sql); System.out.println("Table insect created successfully....!"); //lets insert some records into it String sql1 = "INSERT INTO insect (name,date,origin) VALUES (''housefly'',''2001-09-10'',''kitchen''), (''millipede'',''2001-09-10'',''driveway''), (''grasshopper'',''2001-09-10'',''front yard'')"; st.execute(sql1); System.out.println("Records inserted successfully...!"); //let print table records String sql2 = "SELECT * FROM insect"; rs = st.executeQuery(sql2); System.out.println("Table records(before resetting auto-increment): "); while(rs.next()) { String name = rs.getString("name"); String date = rs.getString("date"); String origin = rs.getString("origin"); System.out.println("Name: " + name + ", Date: " + date + ", Origin: " + origin); } //lets reset auto increment using ALTER table statement... String reset = "ALTER TABLE INSECT AUTO_INCREMENT = 5"; st.execute(reset); System.out.println("Auto-increment reset successsfully...!"); //lets insert some more records.. String sql3 = "INSERT INTO insect (name,date,origin) VALUES (''spider'', ''2000-12-12'', ''bathroom''), (''larva'', ''2012-01-10'', ''garden'')"; st.execute(sql3); System.out.println("Records inserted successfully..!"); String sql4 = "SELECT * FROM insect"; rs = st.executeQuery(sql4); System.out.println("Table records(after resetting auto-increment): "); while(rs.next()) { String name = rs.getString("name"); String date = rs.getString("date"); String origin = rs.getString("origin"); System.out.println("Name: " + name + ", Date: " + date + ", Origin: " + origin); } }catch(Exception e) { e.printStackTrace(); } } }
Output
The output obtained is as shown below −
Table insect created successfully....! Records inserted successfully...! Table records(before resetting auto-increment): Name: housefly, Date: 2001-09-10, Origin: kitchen Name: millipede, Date: 2001-09-10, Origin: driveway Name: grasshopper, Date: 2001-09-10, Origin: front yard Auto-increment reset successsfully...! Records inserted successfully..! Table records(after resetting auto-increment): Name: housefly, Date: 2001-09-10, Origin: kitchen Name: millipede, Date: 2001-09-10, Origin: driveway Name: grasshopper, Date: 2001-09-10, Origin: front yard Name: spider, Date: 2000-12-12, Origin: bathroom Name: larva, Date: 2012-01-10, Origin: garden
import mysql.connector # Establishing the connection connection = mysql.connector.connect( host=''localhost'', user=''root'', password=''password'', database=''tut'' ) # Creating a cursor object cursorObj = connection.cursor() # Creating the ''insect'' table create_table_query = '''''' CREATE TABLE insect ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, PRIMARY KEY (id), name VARCHAR(30) NOT NULL, date DATE NOT NULL, origin VARCHAR(30) NOT NULL ); '''''' cursorObj.execute(create_table_query) print("Table ''insect'' is created successfully!") # Inserting records into the ''insect'' table insert_query = "INSERT INTO insect (Name, Date, Origin) VALUES (%s, %s, %s);" values = [ (''housefly'', ''2001-09-10'', ''kitchen''), (''millipede'', ''2001-09-10'', ''driveway''), (''grasshopper'', ''2001-09-10'', ''front yard'') ] cursorObj.executemany(insert_query, values) print("Values inserted successfully!") # Displaying the contents of the ''insect'' table display_table_query = "SELECT * FROM insect;" cursorObj.execute(display_table_query) results = cursorObj.fetchall() print("ninsect Table:") for result in results: print(result) # Resetting the auto-increment value of the ''id'' column reset_auto_inc_query = "ALTER TABLE insect AUTO_INCREMENT = 5;" cursorObj.execute(reset_auto_inc_query) print("Auto-increment value reset successfully!") # Inserting additional records into the ''insect'' table insert_query = "INSERT INTO insect (name, date, origin) VALUES (''spider'', ''2000-12-12'', ''bathroom'');" cursorObj.execute(insert_query) print("Value inserted successfully!") insert_again_query = "INSERT INTO insect (name, date, origin) VALUES (''larva'', ''2012-01-10'', ''garden'');" cursorObj.execute(insert_again_query) print("Value inserted successfully!") # Displaying the updated contents of the ''insect'' table display_table_query = "SELECT * FROM insect;" cursorObj.execute(display_table_query) results = cursorObj.fetchall() print("ninsect Table:") for result in results: print(result) # Closing the cursor and connection cursorObj.close() connection.close()
Output
The output obtained is as shown below −
Table ''insect'' is created successfully! Values inserted successfully! insect Table: (1, ''housefly'', datetime.date(2001, 9, 10), ''kitchen'') (2, ''millipede'', datetime.date(2001, 9, 10), ''driveway'') (3, ''grasshopper'', datetime.date(2001, 9, 10), ''front yard'') Auto-increment value reset successfully! Value inserted successfully! Value inserted successfully! insect Table: (1, ''housefly'', datetime.date(2001, 9, 10), ''kitchen'') (2, ''millipede'', datetime.date(2001, 9, 10), ''driveway'') (3, ''grasshopper'', datetime.date(2001, 9, 10), ''front yard'') (5, ''spider'', datetime.date(2000, 12, 12), ''bathroom'') (6, ''larva'', datetime.date(2012, 1, 10), ''garden'')