[英]Efficient SQL query with multiple selects
I'm currently at university and doing a project where I have queries such as: 我目前在大学里,正在做一个项目,我对此有疑问:
Select * from recent_purchases where customer_id in
( select customer_id from
customers where name like '%john%'
)
I'm not sure if this is the most idiomatic way of doing things or if I'm missing the "correct" way of doing it - it certainly feels a bit clunky. 我不确定这是否是最惯用的做事方式,或者我是否错过了“正确的”做事方式-它确实感觉有些笨拙。 I don't really understand joins yet.
我还不太了解加入。 Sorry if a stupid question.
对不起,如果有一个愚蠢的问题。
Use an INNER JOIN
instead of a Sub-Select in the WHERE
clause: 在
WHERE
子句中使用INNER JOIN
而不是Sub-Select:
Select *
from recent_purchases rp
inner join customers c on c.customer_id = rp.customer_id
where c.name like '%john%'
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