Wildcards

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 −

CREATETABLE CUSTOMERS (
   ID INTNOTNULL,
   NAME VARCHAR(20)NOTNULL,
   AGE INTNOTNULL,
   ADDRESS CHAR(25),
   SALARY DECIMAL(18,2),PRIMARYKEY(ID));

The following INSERT query adds records into the CUSTOMERS table −

INSERTINTO 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