仅基于一个键加入三个表

Question

大家好，大家好，

TABLE_1

id       c2
-----------
id4     5     
id1     5
id3      4
id2     4

TABLE_2

-----------
id       c1
-----------
id1      5     
id2      5
id3      4
id4      4 

TABLE_3

-----------
id       c1
-----------
id3      5     
id1      5
id2     4
id4      4

加入这三个表后，我会得到如下表所示。 目标

----------------
id       c1c2c3
----------------
id1      555     
id2      544
id4      454
id3      445

如果您不介意帮助我，请。但我的表只有一个唯一的密钥。我的数据库是mysql 5.1。

Answer 1

试试这个

SELECT T1.ID,concat(T2.c1,T1.c2,T3.c3 ) AS C1C2C3
FROM Table1 T1 JOIN Table2 T2 On T1.id =T2.id JOIN Table3 T3 On T3.id =T1.id
ORDER BY RIGHT(T1.ID,1)

<强> Fiddle Demo

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<强> O / P：

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id       c1c2c3
----------------
id1      555     
id2      544
id3      445
id4      454

Answer 2

select t1.id, concat(t2.c1,t1.c2,t3.c3 ) as 'c1c2c3' from table_1 t1 inner
join table_2 t2 inner join table_3 t3 on t2.id=t1.id 
and t3.id=t1.id and t3.id=t2.id order by c1c2c3 desc