MySQL：查看前1000中是否存在值

Question

如何检查前1000行中是否存在值，以及它是否确实返回信息。

像

这样的东西

select cme_fbid 
from table1 if exists(select cme_fbid from table1 limit 1000)

Answer 1

SELECT
    CASE 
        WHEN EXISTS(SELECT cme_fbid FROM table1 LIMIT 1000) THEN t.cme_fbid
        ELSE NULL
    END
    FROM table1 t

Answer 2

select cme_fbid 
from table1
where cme_fbid in (
    select cme_fbid
    from table1
    limit 1000)

您可能希望在内部查询中添加order by以获得一致/有意义的结果。

Answer 3

使用子查询来限制您查看的数据：

select cme_fbid 
from (select * from table1 order by someThing limit 1000) x
where someField = someValue

Answer 4

select count(*) as cnt from table1 where cme_fbid is not null and cme_fbid <> 0 limit 1000 order by id

或在

上使用mysql_row_count

select cme_fbid from table1 where cme_fbid is not null and cme_fbid <> 0 limit 1000 order by id