mysql 排序后， 如何加上序列号？

mysql>

select

*

from

a

+-----+

|

col

|

+-----+

|

0

|

|

1

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2

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3

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4

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5

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6

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|

7

|

+-----+

8

rows

in

set

(0.00

sec)

mysql>

set

@i

:=

0

select

@i

:=

@i

+

1

as

`order`,

a.*

from

a

order

by

col

desc

+-------+-----+

|

order

|

col

|

+-------+-----+

|

1

|

7

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2

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6

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3

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5

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4

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5

|

3

|

|

6

|

2

|

|

7

|

1

|

|

8

|

0

|

+-------+-----+

8

rows

in

set

(0.00

sec)

mysql>

比如说你创建了一个表userinfos

create table userinfos(

userid int primary key,

username varchar(20)

)

//给userinfos添加序列

update userinfos set userid = last_insert_id(userid+1)

//然后查询序列

select last_insert_id()

或者也可以这样

create table userinfos(

userid int primary key not null auto_increment,

username varchar(20)

)

select a.*,

(select count(*) from tbl where col<=a.col) as rownum

from tbl a

mysql 没有oracle里面的rownum函数，用这个sql可以模拟下，但是如果数据量大的话，可能执行很慢。

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