MySQL Reference Manual :: 12.3.1 String Comparison Functions

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.

With LIKE you can use the following two wildcard characters in the pattern:

mysql> SELECT 'David!' LIKE 'David_';
        -> 1
mysql> SELECT 'David!' LIKE '%D%v%';
        -> 1

To test for literal instances of a wildcard character, precede the character with the escape character. If you don't specify the ESCAPE character, '\' is assumed.

mysql> SELECT 'David!' LIKE 'David\_';
        -> 0
mysql> SELECT 'David_' LIKE 'David\_';
        -> 1

To specify a different escape character, use the ESCAPE clause:

mysql> SELECT 'David_' LIKE 'David|_' ESCAPE '|';
        -> 1

The following two statements illustrate that string comparisons are not case sensitive unless one of the operands is a binary string:

mysql> SELECT 'abc' LIKE 'ABC';
        -> 1
mysql> SELECT 'abc' LIKE BINARY 'ABC';
        -> 0

In MySQL, LIKE is allowed on numeric expressions. (This is an extension to the standard SQL LIKE.)

mysql> SELECT 10 LIKE '1%';
        -> 1

Note: Because MySQL uses the C escape syntax in strings (for example, '\n' to represent newline), you must double any '\' that you use in your LIKE strings. For example, to search for '\n', specify it as '\\n'. To search for '\', specify it as '\\\\' (the backslashes are stripped once by the parser and another time when the pattern match is done, leaving a single backslash to be matched).

expr NOT LIKE pat [ESCAPE 'escape-char']

This is the same as NOT (expr LIKE pat [ESCAPE 'escape-char']).

expr NOT REGEXP pat , expr NOT RLIKE pat

This is the same as NOT (expr REGEXP pat).

expr REGEXP pat , expr RLIKE pat

Performs a pattern match of a string expression expr against a pattern pat. The pattern can be an extended regular expression. The syntax for regular expressions is discussed in Appendix G, MySQL Regular Expressions. Returns 1 if expr matches pat, otherwise returns 0. If either expr or pat is NULL, the result is NULL. RLIKE is a synonym for REGEXP, provided for mSQL compatibility.

The pattern need not be a literal string. For example, it can be specified as a string expression or table column.

Note: Because MySQL uses the C escape syntax in strings (for example, '\n' to represent newline), you must double any '\' that you use in your REGEXP strings.

As of MySQL 3.23.4, REGEXP is not case sensitive for normal (not binary) strings.

mysql> SELECT 'Monty!' REGEXP 'm%y%%';
        -> 0
mysql> SELECT 'Monty!' REGEXP '.*';
        -> 1
mysql> SELECT 'new*\n*line' REGEXP 'new\\*.\\*line';
        -> 1
mysql> SELECT 'a' REGEXP 'A', 'a' REGEXP BINARY 'A';
        -> 1  0
mysql> SELECT 'a' REGEXP '^[a-d]';
        -> 1

REGEXP and RLIKE use the current character set (ISO-8859-1 Latin1 by default) when deciding the type of a character. However, these operators are not multi-byte safe.

STRCMP(expr1,expr2)

STRCMP() returns 0 if the strings are the same, -1 if the first argument is smaller than the second according to the current sort order, and 1 otherwise.

mysql> SELECT STRCMP('text', 'text2');
        -> -1
mysql> SELECT STRCMP('text2', 'text');
        -> 1
mysql> SELECT STRCMP('text', 'text');
        -> 0

As of MySQL 4.0, STRCMP() uses the current character set when performing comparisons. This makes the default comparison behavior case insensitive unless one or both of the operands are binary strings. Before MySQL 4.0, STRCMP() is case sensitive.