What is the role of trim in mysql

The function of trim function in mysql is to filter the specified string, the format is [TRIM([{BOTH | LEADING | TRAILING} [remstr] FROM] str)].

The trim function can filter the specified string:

Full format: TRIM([{BOTH | LEADING | TRAILING} [remstr] FROM ] str)

Simplified format: TRIM([remstr FROM] str)

Returns the string str in which all remstr prefixes and/or suffixes have been removed. If none of the classifiers BOTH, LEADIN or TRAILING is given, BOTH is assumed. remstr is optional and can remove spaces if not specified.

mysql> SELECT TRIM('  bar   ');
        -> 'bar'
mysql> SELECT TRIM(LEADING 'x' FROM 'xxxbarxxx');   --删除指定的首字符 x
        -> 'barxxx'
mysql> SELECT TRIM(BOTH 'x' FROM 'xxxbarxxx');      --删除指定的首尾字符 x
        -> 'bar'
mysql> SELECT TRIM(TRAILING 'xyz' FROM 'barxxyz');  --删除指定的尾字符 x
        -> 'barx'

The function to remove left spaces in mysql:

LTRIM(str);

mysql> SELECT LTRIM('  barbar');
        -> 'barbar'

The function to remove right spaces in mysql:

RTRIM(str):

mysql> SELECT RTRIM('barbar   ');
-> 'barbar'

More related free learning recommendations: mysql tutorial(video)

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