一条语句中有两个选择语句 [英] Two select statements in a single statement

问题描述

我基本上有两个名为images和users的表. images表具有以下字段:

I basically have two tables called images and users. The images table has the following fields:

i_id | s_id | u_id | name | filename |

u_id是users表中的u_id字段的外键，该字段具有以下字段:

u_id is a foreign key to the u_id field in the users table, which has these fields:

u_id | username | password | email |

我正在运行这样的查询:

I'm running a query like this:

SELECT s_id, u_id, name, filename, filesize FROM images WHERE name = 'fYhWId'

这将返回用户的u_id等.但是我想返回用户的用户名，而不是他们的u_id.因此，基本上，在该SELECT语句中，我还想运行:

This returns the u_id of the user, among other things. But I want to return the users username, not their u_id. So basically, within that SELECT statement, I also want to run:

SELECT username FROM users WHERE u_id = 1

我可以为此使用两个查询，但是我试图减少我的应用程序运行的查询，而且我知道有一种方法可以将其组合成一个查询，但是我只是不知道:<

I could use two queries for this, but I'm trying to cut down on the queries my application runs, and I know there's a way to combine this into one query, but I just don't know it :<

有人知道答案吗?谢谢！

Does anyone know the answer? Thanks!

推荐答案

SELECT username FROM users WHERE u_id = (SELECT TOP 1 u_id FROM images WHERE name = 'fYhWId')

或

SELECT username FROM users WHERE u_id IN (SELECT u_id FROM images WHERE name = 'fYhWId')

或

SELECT username,  s_id, images.u_id, name, filename, filesize 
FROM images 
INNER JOIN users on images.u_id = users.u_id
WHERE name = 'fYhWId'

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