MySQL string processing

MySQL string processing is a basic knowledge. The following describes MySQL string processing in detail and hopes to help you learn MySQL strings.

LEFT: Extract from the LEFT

Mysql> select left ('foobarbar', 5 );

-> 'Fooba'
Mysql> select left ('I am a Chinese', 2 );

-> 'I am'

RIGHT: capture from the RIGHT

Mysql> select right ('foobarbar', 5 );

-> 'Arbar'
Mysql> select right ('I am a Chinese', 2 );

-> 'Chinese'

SUBSTR (SUBSTRING): truncates a SUBSTRING.
Mysql> select substring ('quadratically ', 5 );

-> 'Ratically'

Mysql> select substring ('foobarbar' FROM 4 );

-> 'Barbar'

Mysql> select substring ('quadratically ', 5, 6 );

-> 'Ratica'

Mysql> select substring ('sakila',-3 );

-> 'Ila'

Mysql> select substring ('sakila',-5, 3 );

-> 'Aki'

Mysql> select substring ('sakila' FROM-4 FOR 2 );

-> 'Ki'

INSTR: returns the position of the substring.
Mysql> select instr ('foobar', 'bar ');

-> 4

Mysql> select instr ('xbar', 'foobar ');

-> 0
 

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