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SQL Wildcards
SQL Wildcards are special characters used as substitutes for one or more characters in a string. They are used with the LIKE operator in SQL, to search for specific patterns in character strings or compare various strings.
The LIKE operator in SQL is case-sensitive, so it will only match strings that have the exact same case as the specified pattern.
Following are the most commonly used wildcards in SQL −
| S.No. | Wildcard & Description |
|---|---|
| 1 |
The percent sign (%) Matches one or more characters. Note − MS Access uses the asterisk (*) wildcard character instead of the percent sign (%) wildcard character. |
| 2 |
The underscore (_) Matches one character. Note − MS Access uses a question mark (?) instead of the underscore (_) to match any one character. |
The percent sign (%) represents zero, one, or multiple characters within a string. The underscore (_) represents a single character or number. These symbols can also be used in combination to perform complex pattern searching and matching in SQL queries.
Syntax
Following is the basic syntax to use wildcard characters −
SELECT * FROM table_name WHERE column_name LIKE [wildcard_pattern];
We can combine N number of conditions using the AND or the OR operators. Here, the [wildcard_pattern] can represent any numeric or string value.
The following table demonstrates various ways of using wildcards in conjunction with the LIKE operator within a WHERE clause:
| S.No. | Statement & Description |
|---|---|
| 1 |
WHERE SALARY LIKE ”200%” Finds any values that start with 200. |
| 2 |
WHERE SALARY LIKE ”%200%” Finds any values that have 200 in any position. |
| 3 |
WHERE SALARY LIKE ”_00%” Finds any values that have 00 in the second and third positions. |
| 4 |
WHERE SALARY LIKE ”2_%_%” Finds any values that start with 2 and are at least 3 characters in length. |
| 5 |
WHERE SALARY LIKE ”%2” Finds any values that end with 2. |
| 6 |
WHERE SALARY LIKE ”_2%3” Finds any values that have a 2 in the second position and end with a 3. |
| 7 |
WHERE SALARY LIKE ”2___3” Finds any values in a five-digit number that start with 2 and end with 3. |
Example
Firstly, let us create a table named CUSTOMERS using the following query −
CREATE TABLE CUSTOMERS ( ID INT NOT NULL, NAME VARCHAR (20) NOT NULL, AGE INT NOT NULL, ADDRESS CHAR (25), SALARY DECIMAL (18, 2), PRIMARY KEY (ID) );
The following INSERT query adds records into the CUSTOMERS table −
INSERT INTO CUSTOMERS VALUES (1, ''Ramesh'', 32, ''Ahmedabad'', 2000.00), (2, ''Khilan'', 25, ''Delhi'', 1500.00), (3, ''Kaushik'', 23, ''Kota'', 2000.00), (4, ''Chaitali'', 25, ''Mumbai'', 6500.00), (5, ''Hardik'', 27, ''Bhopal'', 8500.00), (6, ''Komal'', 22, ''Hyderabad'', 4500.00), (7, ''Muffy'', 24, ''Indore'', 10000.00);
The table will be created as −
| ID | NAME | AGE | ADDRESS | SALARY |
|---|---|---|---|---|
| 1 | Ramesh | 32 | Ahmedabad | 2000.00 |
| 2 | Khilan | 25 | Delhi | 1500.00 |
| 3 | Kaushik | 23 | Kota | 2000.00 |
| 4 | Chaitali | 25 | Mumbai | 6500.00 |
| 5 | Hardik | 27 | Bhopal | 8500.00 |
| 6 | Komal | 22 | Hyderabad | 4500.00 |
| 7 | Muffy | 24 | Indore | 10000.00 |
Here, we are displaying all the records from the CUSTOMERS table where the SALARY starts with 200.
SELECT * FROM CUSTOMERS WHERE SALARY LIKE ''200%'';
Output
This would produce the following result.
| ID | NAME | AGE | ADDRESS | SALARY |
|---|---|---|---|---|
| 1 | Ramesh | 32 | Ahmedabad | 2000.00 |
| 3 | Kaushik | 23 | Kota | 2000.00 |
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