SQL LIKE Condition

SQL: LIKE Condition

The SQL LIKE condition allows you to use wildcards in the SQL WHERE clause of an SQL statement. This allows you to perform pattern matching. The SQL LIKE condition can be used in any valid SQL statement - SQL SELECT statement, SQL INSERT statement, SQL UPDATE statement, or SQL DELETE statement.

The patterns that you can choose from are:

·         % allows you to match any string of any length (including zero length)

·         _ allows you to match on a single character

SQL LIKE Condition - Using % wildcard example

Let's explain how the % wildcard works in the SQL LIKE condition. We are going to try to find all of the suppliers whose name begins with 'Hew'.

SELECT * FROM suppliers

WHERE supplier_name like 'Hew%';

You can also using the % wildcard multiple times within the same string. For example,

SELECT * FROM suppliers

WHERE supplier_name like '%bob%';

In this SQL LIKE condition example, we are looking for all suppliers whose name contains the characters 'bob'.

You could also use the SQL LIKE condition to find suppliers whose name does not start with 'T'.

For example:

SELECT * FROM suppliers

WHERE supplier_name not like 'T%';

By placing the not keyword in front of the SQL LIKE condition, you are able to retrieve all suppliers whose name does not start with 'T'.

SQL LIKE Condition - Using _ wildcard example

Next, let's explain how the _ wildcard works in the SQL LIKE condition. Remember that the _ is looking for only one character.

For example:

SELECT * FROM suppliers

WHERE supplier_name like 'Sm_th';

This SQL LIKE condition example would return all suppliers whose name is 5 characters long, where the first two characters is 'Sm' and the last two characters is 'th'. For example, it could return suppliers whose name is 'Smith', 'Smyth', 'Smath', 'Smeth', etc.

Here is another example:

SELECT * FROM suppliers

WHERE account_number like '12317_';

You might find that you are looking for an account number, but you only have 5 of the 6 digits. The example above, would retrieve potentially 10 records back (where the missing value could equal anything from 0 to 9). For example, it could return suppliers whose account numbers are:

123170, 123171, 123172, 123173, 123174, 123175, 123176, 123177, 123178, 123179

SQL LIKE Condition - Using Escape Characters example

Next, in Oracle, let's say you wanted to search for a % or a _ character in the SQL LIKE condition. You can do this using an Escape character.

Please note that you can only define an escape character as a single character (length of 1).

For example:

SELECT * FROM suppliers

WHERE supplier_name LIKE '!%' escape '!';

This SQL LIKE condition example identifies the ! character as an escape character. This statement will return all suppliers whose name is %.

Here is another more complicated example using escape characters in the SQL LIKE condition.

SELECT * FROM suppliers

WHERE supplier_name LIKE 'H%!%' escape '!';

This SQL LIKE condition example returns all suppliers whose name starts with H and ends in %. For example, it would return a value such as 'Hello%'.

You can also use the escape character with the _ character in the SQL LIKE condition.

For example:

SELECT * FROM suppliers

WHERE supplier_name LIKE 'H%!_' escape '!';

This SQL LIKE condition example returns all suppliers whose name starts with H and ends in _. For example, it would return a value such as 'Hello_'.