-- 慢SELECT * FROM table_name ORDER BY rand() LIMIT 5;-- 较慢SELECT * FROM `table`WHERE id >= (SELECT floor( RAND() * ((SELECT MAX(id) FROM `table`)-(SELECT MIN(id) FROM `table`)) + (SELECT MIN(id) FROM `table`)))ORDER BY id LIMIT 1;-- 快 `table 有 id 字段SELECT *FROM `table` AS t1 JOIN (SELECT ROUND(RAND() * ((SELECT MAX(id) FROM `table`)-(SELECT MIN(id) FROM `table`))+(SELECT MIN(id) FROM `table`)) AS id) AS t2WHERE t1.id >= t2.idORDER BY t1.id LIMIT 1;-- 快 `table 没有有 id 字段select * from (select @rownum:=@rownum + 1 as id,value from `table`,(select @rownum:=0) as a) as t1 join ( select round( rand() * ( (select max(b.id) from (select @rownum_max:=@rownum_max + 1 as id,value from `table`,(select @rownum_max:=0) as a) as b ) - (select min(b.id) from (select @rownum_min:=@rownum_min + 1 as id,value from `table`,(select @rownum_min:=0) as a) as b ) )) + (select min(b.id) from (select @rownum_min1:=@rownum_min1 + 1 as id,value from `table`,(select @rownum_min1:=0) as a) as b ) as id ) as t2on t1.id>= t2.idorder by t1.id limit 1
缺点:
每次查询后会获得连续的n条数据
解决办法:
每次查一条数据,重复查询n 次