我有下面的 sql 查询，执行时间太长，请问有内部联接的替代方案来解决我的问题吗？因为当我删除 3 或 4 个联接时，查询执行得更快。
SELECT p.first_name, p.last_name, p.x, p.dob,'name', w.id_table1, w.type, w.stype, w.ploc, w.dat, w.created_at, av.item as table1_edge , av1.item as sdf ,av2.item as sd, av3.item as odor, av4.item as xz, av5.value as xxx , av9.item as cc, av10.item as cxz
FROM table1 w
INNER JOIN table2 a ON w.id_table1 = a.table1_id_table1
INNER JOIN table3 av ON a.id_table2 = av.id_table3 and av.sub_group = 'x1'
INNER JOIN table3 av1 ON a.id_table2 = av1.id_table3 and av1.sub_group = 'x2'
INNER JOIN table3 av2 ON a.id_table2 = av2.id_table3 and av2.sub_group = 'x3'
INNER JOIN table3 av3 ON a.id_table2 = av3.id_table3 and av3.sub_group = 'x4'
INNER JOIN table3 av4 ON a.id_table2 = av4.id_table3 and av4.sub_group = 'x5'
INNER JOIN table3 av5 ON a.id_table2 = av5.id_table3 and av5.sub_group = 'x6' and av6.item like 's%'
INNER JOIN table3 av6 ON a.id_table2 = av6.id_table3 and av6.sub_group = 'x7' and av6.item like 'x%'
INNER JOIN table3 av7 ON a.id_table2 = av7.id_table3 and av7.sub_group = 'x8' and av6.item like 'z%'
INNER JOIN table3 av8 ON a.id_table2 = av8.id_table3 and av8.sub_group = 'x9' and av6.item like 'y%'
INNER JOIN table3 av9 ON a.id_table2 = av9.id_table3 and av9.sub_group = 'x10'
INNER JOIN table3 av10 ON a.id_table2 = av10.id_table3 and av10.sub_group = 'x11'
INNER JOIN table0 p ON w.table0_id_table0 = p.id_table0
where w.created_at between '1991-12-09 00:00:00' and now() and user_id_user = 4
数据:
表0
名字
姓氏
出生日期
...
table1
id_table1
类型
stype
...
最佳答案
您是否尝试过使用子查询来代替执行时间较长的内部联接？
示例:
select a.id, b.id, c.id
from table a
inner join (
select id
from tableb
where b = 'x1'
) as b on b.id = a.id
inner join (
select id
from tablec
where c = 'x2'
) as c on c.id = a.id
关于mysql - SQL INNER join 执行时间太长，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39931521/