如何在选择查询中生成自动增量字段

Question

例如,我有一个包含2列的表,first_name并last_name带有这些值

Ali           Khani
Elizabette    Amini
Britney       Spears
,...

我想编写一个select生成如下表的查询:

1     Ali           Khani
2     Elizabette    Amini
3     Britney       Spears
,...

谢谢你的帮助.

Answer 1

如果是MySql,你可以试试

SELECT @n := @n + 1 n,
       first_name, 
       last_name
  FROM table1, (SELECT @n := 0) m
 ORDER BY first_name, last_name

SQLFiddle

而对于SQLServer

SELECT row_number() OVER (ORDER BY first_name, last_name) n,
       first_name, 
       last_name 
  FROM table1 

SQLFiddle

Answer 2

这是SQL server, Oracle, PostgreSQL支持窗口的功能.

SELECT  ROW_NUMBER() OVER (ORDER BY first_name, last_name)  Sequence_no,
        first_name,
        last_name
FROM    tableName

• SQLFiddle演示

Answer 3

如果您没有自然分区值，并且只需要一个有序数字，而不管分区如何，您只需对常量执行 row_number 即可，在下面的示例中，我刚刚使用了“X”。希望这对某人有帮助

select 
    ROW_NUMBER() OVER(PARTITION BY num ORDER BY col1) as aliascol1, 
    period_next_id, period_name_long
from 
(
  select distinct col1, period_name_long, 'X' as num
  from {TABLE} 
) as x