Question

我有问题...... 在table1中我有一个id，我必须比较table2中的id，然后获取table2中的第二个id并将其与table3进行比较并得到一个数据。实施例

TABLE1
ID   NAME ECC...
1      Jhon
2      Frank

TABLE2
ID ID2 ECC..
1   4
2   8

TABLE3
ID NAME
4    Sea
8    Hello

如果我查找id 1，结果必须是Sea 如果我查找id 2，结果必须是Hello

谢谢！

Answer 1

 SELECT Table3.NAME
   FROM Table1
  INNER JOIN Table2
 ON Table1.ID = Table2.ID
  INNER JOIN Table3
 ON Table3.ID = Table2.ID2
  WHERE Table1.ID = 1  -- Your Search here

Answer 2

您应该使用加入。

您的查询将如下所示：

SELECT t3.name
FROM table3 t3
LEFT JOIN table2 t2 ON t3.id = t2.id2
LEFT JOIN table1 t1 ON t2.id2 = t1.id
WHERE t1.id = <your_number>

Answer 3

查询：

 SELECT a.name As Name FROM table3 a JOIN 
 (SELECT b.id2 AS id FROM table1 a JOIN table2 b ON a.id = b.id)b
 ON a.id = b.id where b.id = <your id number (1,2) Anything>

Answer 4

select Table2.Id,Table3.Name from Table1 inner join Table2 on Table2.ID2 = Table3.Id

Answer 5

应该是这样的：

select table3.name as name3
from table3
where table3.ID = table2.ID2
and table2.ID = table1.ID
and table1.ID = <YOURNUMBERHERE>

SELECT * FROM table1，table2，table3

5 个答案: