如何从第二个表中获取我知道id的第一个表

Question

我需要得到两个表，这里是表结构

表A

• 用户ID
• 用户名
• 状态
• IntroCode

表B

• IntroCode
• 用户ID

我想在tblA.IntroCode = tblB.IntroCode上获取表格数据并与表b连接，然后获取tblB.userID的用户名。我怎么能这样加入？

我尝试了一半，卡在中间，请帮忙。谢谢你的回复

Answer 1

这只是一个简单的连接。

SELECT  a.*, b.*    -- select your desired columns here
FROM    tableA a
        INNER JOIN tableB b
            ON a.IntroCode = b.IntroCode
WHERE   b.userid = valueHere

更新1

SELECT  a.UserID, 
        a.`Username` OrigUserName,
        a.`Status`,
        c.`Username` IntroUserName
FROM    tableA a
        INNER JOIN tableB b
            ON a.IntroCode = b.IntroCode
        INNER JOIN tableA c
            ON b.userID = c.userID
-- WHERE b.UserID = valueHere       -- extra condition here

Answer 2

SELECT column_name(s)
FROM TableA
LEFT JOIN TableB
ON TableA.UserID=TableB.UserID

Answer 3

SELECT B.userID from TableA A
LEFT JOIN TableB B on A.IntroCode=B.IntroCode

Answer 4

select a.*,b.IntroCode  from TableA a left join TableB b
on a.IntroCode = b.IntroCode 

Answer 5

您必须为具有相同名称的列提供唯一值：

SELECT  a.UserID as uid_a, b.UserID as uid_b
FROM    tableA a
INNER JOIN tableB b ON a.IntroCode = b.IntroCode
WHERE   b.UserID = 1

Answer 6

使用此查询。

 SELECT TableA.Username FROM TableA JOIN TableB ON (TableA.IntroCode = TableB.IntroCode);

Answer 7

使用此查询

SELECT  *  FROM tblA INNER JOIN tblB ON tblA.IntroCode = tblB.IntroCode where tblB.userid = value