分组IN语句sql

问题描述

假设我有一个名为 table1 的表，它对应的列是 col1、col2、col3 和 col4.

lets say I have a table called table1 and it's corresponding columns are col1, col2, col3 and col4 for example.

什么是等效的事情:

-- note that the following query will not work
SELECT * 
  FROM table1 
 WHERE col1, col2 IN (SELECT col1, col2 
                        FROM table1 
                       WHERE col3 < 4)

我是否必须在我的数据库中合并 col1 和 col2 才能完成这项工作?如果我将 col1 和 col2 合并到 col1_2 中，那么我将能够通过编写上述查询:

Do I have to merge col1 and col2 in my database to make this work? If I merge col1 and col2 into col1_2 then I will be able to make the above query work by writing:

SELECT * 
  FROM table1 
 WHERE col1_2 IN (SELECT col1_2 
                    FROM table1 
                   WHERE col3 < 4)

IN 子句在使用一列时工作正常.如果我可以将它与多个列一起使用而不必修改数据库，那就太好了.

The IN clause works fine when using one column. it will be nice if I could use it with several columns without having to modify the database.

推荐答案

SELECT * from table1 t1, table1 t2
where t1.col1=t2.col1 and t1.COl2=t2.Col2 and t1.col3<4

试试这个

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