使用下面的函数来进行模糊查询,如果出现的位置>0,表示包含该字符串。
查询效率比like要高。
如:
table.field like ‘%AAA%’ 可以改为 locate (‘AAA’ , table.field) > 0
注:locate(substr,str)
用explain查看结果,rows越少越好!
1、用like查询
2、用locate查询
可以明显的看到,在此处虽然两者的rows一样,但是filtered的值,用了locate后的值是用like的值的10倍。
注:The filtered
column
is described in the MySQL
manual:
The filtered column indicates an estimated percentage of table rows that will be filtered by the table condition. That is, rows shows the estimated number of rows examined and rows × filtered
/ 100 shows the number of rows that will be joined with previous tables. This column is displayed if you use EXPLAIN EXTENDED. (New in MySQL 5.1.12)
也就是说,filtered的越高越好!
时间: 2024-10-24 02:30:02