FIND_IN_SET(str,strlist)函數解析

FIND_IN_SET(str,strlist)【Mysql中的函數】

1.語法

Returns a value in the range of 1 to N if the string str is in the string
list strlist consisting of N substrings. A string list is a string composed
of substrings separated by , characters.
If the first argument is a constant string and the second is a column of
type SET, the FIND_IN_SET() function is optimized to use bit arithmetic. 
Returns 0 if str is not in strlist or if strlist is the empty string.
Returns NULL if either argument is NULL. This function does not work properly 
if the first argument contains a comma (,) character.

2.示例

mysql> select find_in_set('b','a,b,c,d'); +----------------------------+
| find_in_set('b','a,b,c,d') | +----------------------------+
| 2 | +----------------------------+
1 row in set (0.02 sec)

mysql> select find_in_set('b','abcd'); +-------------------------+
| find_in_set('b','abcd') | +-------------------------+
| 0 | +-------------------------+
1 row in set (0.00 sec)

mysql> select find_in_set('bcd','abcd'); +---------------------------+
| find_in_set('bcd','abcd') | +---------------------------+
| 0 | +---------------------------+
1 row in set (0.00 sec)

mysql> select find_in_set('b,','abcd'); +--------------------------+
| find_in_set('b,','abcd') | +--------------------------+
| 0 | +--------------------------+
1 row in set (0.00 sec)