MySQL LIKE operator

LIKE operator

MySQL LIKE operator checks whether a specific character string matches a specified pattern.

This function is useful in -

• It allows for pattern matching within strings. This is crucial for searching and filtering data based on specific patterns or characters.
• The % and _ are wildcards that can represent any number of characters or a single character, respectively.
• It allows for complex search patterns by combining multiple wildcards and characters.
• LIKE is commonly used in WHERE clauses to filter rows based on specific patterns or conditions, making it a crucial part of data retrieval.
• In natural language processing and text mining, LIKE is invaluable for extracting relevant information from unstructured text.
• By combining LIKE with LOWER() or UPPER() functions, you can perform case-insensitive searches, which is particularly useful when dealing with user-generated data.
• This is beneficial when you want to find similar strings, even if they're not identical.

Syntax:

expr LIKE pat [ESCAPE 'escape_char']

• Pattern matching using SQL simple regular expression comparison. Returns 1 (TRUE) or 0 (FALSE). If either expr or pat is NULL, the result is NULL.
• The pattern need not be a literal string. For example, it can be specified as a string expression or table column.
• Per the SQL standard, LIKE performs matching on a per-character basis, thus it can produce results different from the = comparison operator.
• LIKE operator uses WILDCARDS (i.e. %, _) to match the pattern. This is very useful to check whether a particular character or string is present in the records.

% is used to match any number of characters, even zero characters.
_ is used to match exactly one character.

To test for literal instances of a wildcard character, precede it by the escape character. If you do not specify the ESCAPE character, “\” is assumed.
\% is used to match one "%" character.
\_ Matches one "_" character

MySQL Version: 8.0

Example: MySQL LIKE operator

The following MySQL statement scans the whole author table to find any author name which has a first name starting with character ‘W’ followed by any characters.

Code:

SELECT aut_name, country          
FROM author 
WHERE aut_name LIKE 'W%';

Relational Algebra Expression:

Relational Algebra Tree:

Sample table: author

Output:

mysql> mysql> SELECT aut_name, country          
    -> FROM author 
    -> WHERE aut_name LIKE 'W%';
+-----------------+---------+
| aut_name        | country |
+-----------------+---------+
| William Norton  | UK      | 
| William Maugham | Canada  | 
| William Anthony | UK      | 
+-----------------+---------+
3 rows in set (0.05 sec)

Example: MySQL LIKE operator matching to end

The following MySQL statement scans the whole author table to find any author which have the name ended with ‘on’ string.

Code:

SELECT aut_name, country 
FROM author     
WHERE aut_name LIKE '%on';

Relational Algebra Expression:

Relational Algebra Tree:

Sample table: author

Output:

mysql> SELECT aut_name, country 
    -> FROM author     
    -> WHERE aut_name LIKE '%on';
+----------------+---------+
| aut_name       | country |
+----------------+---------+
| William Norton | UK      | 
| Thomas Merton  | USA     | 
| Piers Gibson   | UK      | 
| Joseph Milton  | USA     | 
+----------------+---------+
4 rows in set (0.00 sec)

Example : MySQL LIKE operator matching within the string

The following MySQL statement scans the whole author table to find any author which have a string ‘an’ in his name. Name of the author is stored in aut_name column.

Code:

SELECT aut_name, country 
FROM author
WHERE aut_name LIKE '%an%';

Relational Algebra Expression:

Relational Algebra Tree:

Sample table: author

Output:

mysql> SELECT aut_name, country 
    -> FROM author
    -> WHERE aut_name LIKE '%an%';
+----------------------+-----------+
| aut_name             | country   |
+----------------------+-----------+
| William Anthony      | UK        | 
| S.B.Swaminathan      | India     | 
| Thomas Morgan        | Germany   | 
| John Betjeman Hunter | Australia | 
| Evan Hayek           | Canada    | 
| Butler Andre         | USA       | 
+----------------------+-----------+
6 rows in set (0.00 sec)

Example : MySQL LIKE operator matching a specified string

The following MySQL statement searches all authors whose home city are such as ‘London’, ’Landon’ etc. the underscore wildcard is used to mention single character.

Code:

SELECT aut_name, country,home_city       
FROM author        
WHERE home_city LIKE 'L_n_on';

Relational Algebra Expression:

Relational Algebra Tree:

Sample table: author

Output:

mysql> SELECT aut_name, country,home_city       
    -> FROM author        
    -> WHERE home_city LIKE 'L_n_on';
+--------------+---------+-----------+
| aut_name     | country | home_city |
+--------------+---------+-----------+
| Piers Gibson | UK      | London    | 
| C. J. Wilde  | UK      | London    | 
+--------------+---------+-----------+
2 rows in set (0.00 sec)

Example : MySQL LIKE operator matching escape character

To search a wildcard character or a combination of a wildcard character and any other character, the wildcard character must be preceded by an ESCAPE string. In MySQL, the default ESCAPE string is "\". The following MySQL statement returns those records, whose isbn_no contain '_16'.

code:

SELECT book_name,isbn_no,no_page,book_price 
FROM book_mast 
WHERE isbn_no LIKE '%\_16%';

Relational Algebra Expression:

Relational Algebra Tree:

Sample table: book_mast

Output:

mysql> SELECT book_name,isbn_no,no_page,book_price 
    -> FROM book_mast 
    -> WHERE isbn_no LIKE '%\_16%';
+---------------------------------+-------------+---------+------------+
| book_name                       | isbn_no     | no_page | book_price |
+---------------------------------+-------------+---------+------------+
| Networks and Telecommunications | 00009790_16 |      95 |      45.00 | 
+---------------------------------+-------------+---------+------------+
1 row in set (0.00 sec)

Example : MySQL LIKE operator matching beginning and ending string

Wildcards can also be used in the middle of a search pattern. The following MySQL statement will find all authors whose name begin with a ‘t’ and end with an ‘n’.

Code:

SELECT aut_name, country
FROM author         
WHERE aut_name LIKE 't%n';

Relational Algebra Expression:

Relational Algebra Tree:

Sample table: author

Output:

mysql> SELECT aut_name, country
    -> FROM author         
    -> WHERE aut_name LIKE 't%n';
+---------------+---------+
| aut_name      | country |
+---------------+---------+
| Thomas Morgan | Germany | 
| Thomas Merton | USA     | 
+---------------+---------+
2 rows in set (0.00 sec)

Slideshow of MySQL Comparison Function and Operators

Previous: LESS THAN OPERATOR(<)
Next: NOT BETWEEN AND