我有一个如下查询。此查询工作正常,但由于我需要检查大量数据,因此运行此查询的速度较慢。
任何人都可以帮我如何优化这个查询?
SELECT * from trn where concat(comp_id,cus_id)
IN (select concat(comp_id,cus_id) FROM cus where sid='A0001')
AND docdate between ('2018-01-01') and ('2018-04-30')
你可以使用EXISTS
:
SELECT t.*
FROM trn t
WHERE EXISTS (SELECT 1
FROM cus c
WHERE c.sid = 'A0001' AND c.comp_id = t.comp_id AND c.cus_id = t.cus_id
) AND
docdate between '2018-01-01' and '2018-04-30';
concat
可能会导致这些性能问题,因为它无法使用索引。
但MySQL支持多列子查询,因此只需删除它:
SELECT * from trn
where (comp_id,cus_id) IN
( select comp_id,cus_id
FROM cus
where sid='A0001'
)
AND docdate between ('2018-01-01') and ('2018-04-30')
你可以使用JOIN
,例如:
SELECT DISTINCT t.*
FROM trn t
JOIN cus c ON t.comp_id = c.comp_id AND t.cus_id = c.cus_id
WHERE c.sid='A0001' AND t.docdate BETWEEN ('2018-01-01') AND ('2018-04-30');