a 表有50万条记录。是一次查出来效果好还是分开查询好?每次执行查询语句50次。
或者怎么优化一下
select
( SELECT COUNT( id ) FROM a WHERE
operator_id=2 and operator_status =0 ) AS todo,
( SELECT COUNT( id ) FROM a WHERE
operator_id=3 ) AS lists,
( SELECT COUNT( id ) FROM a
WHERE operator_id=4 and operator_status > 0 ) AS doen ,
( SELECT COUNT( id ) FROM a'
WHERE operator_status =-1 ) AS nobody
'; SELECT COUNT( id ) FROM a WHERE operator_id=2 and operator_status =0
SELECT COUNT( id ) FROM a WHERE operator_id=3
SELECT COUNT( id ) FROM a' WHERE operator_status =-1
selectmysql
或者怎么优化一下
select
( SELECT COUNT( id ) FROM a WHERE
operator_id=2 and operator_status =0 ) AS todo,
( SELECT COUNT( id ) FROM a WHERE
operator_id=3 ) AS lists,
( SELECT COUNT( id ) FROM a
WHERE operator_id=4 and operator_status > 0 ) AS doen ,
( SELECT COUNT( id ) FROM a'
WHERE operator_status =-1 ) AS nobody
'; SELECT COUNT( id ) FROM a WHERE operator_id=2 and operator_status =0
SELECT COUNT( id ) FROM a WHERE operator_id=3
SELECT COUNT( id ) FROM a' WHERE operator_status =-1
selectmysql
count(case when operator_id=3 then 1 end),
count(casen when operator_status =-1 then 1 end)
from a