mysql in 查询, 里面的每个条件都指定返回条数,能否实现,怎么写?
SELECT column_name(s)
FROM table_name
WHERE column_name IN (value1,value2)
table_name 里面包含value1和value2的值有很多条,能否指定返回条数。
类似:
select * from table_name where column_name = value1 limit 5;
select * from table_name where column_name = value2 limit 5;
或有其他方法实现这个查询?
It is the conversion of or/in/union all. The performance is also better than union all, and it can also meet the requirement of returning the specified number of items as you said.
Your sql seems inconsistent with your description
SELECT column_name(s),count(column_name(s))
FROM table_name
WHERE column_name(s) IN (value1,value2,...)
group by column_name(s) )
There is nothing logically wrong with this way of writing, but please take a look at the execution plan after writing it. If I remember well, the efficiency of mysql's in is not high. If it is a single table, I can't think of anything good. Idea