Question

SELECT * FROM TT 
ORDER BY (SELECT AGE 
          FROM TTT 
          WHERE NAME='TANDEL'
          );

结果是，

JOHN    2
PRAVEEN 2
KUMAR   2
RAKESH  2
WASIB   2
GURUNG  2
DAYALAN 5
DEEPAK  2
TANDEL  5
RAGHU   5
GIGA    5
DEEPA   5
DEVARAJ 2

注意：表TT和TTT都有相同的数据。

Answer 1

很简单，它不起作用。 Order By需要一列或多列，如果随机数据传递给它而不是列名，它什么也不做。

Answer 2

排序依据需要一列或一些列

ORDER BY CLAUSE

SELECT * 
FROM TT 
ORDER BY colname

Answer 3

在order by子句中，我们可以添加两件事：

列名
```
Select * from TTT order by age;
```

要过滤的Coulmn号码

Select * from TTT order by 2;//if age is the second column in the table 
            or
Select name,age from TTT order by 2; // this will order by age

在以下情况下，内部查询

  SELECT AGE 
      FROM TTT 
      WHERE NAME='TANDEL'

将返回5

和父查询

  SELECT * FROM TT 
   ORDER BY 5

Order By如何在此查询中工作

3 个答案: