--如果想进行断号处理,则不能用自增,用如下的存储过程实现. --以下三段,存储过程一样,只是显示不同数据时的情况. --这是没有数据时. create table tb(id int) gocreate proc my_proc @id int OUTPUT as begin if not exists (select 1 from tb) set @id = 1 else begin select @id = min(m.px) + 1 from (select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) m, (select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) n where m.id <> n.id - 1 and m.px = n.px - 1 if @id is null select @id = max(id) + 1 from tb end
end godeclare @id as intexec my_proc @id outputselect @iddrop table tb drop proc my_proc/*
----------- 1(所影响的行数为 1 行) */--这是存在断号时.create table tb(id int) insert into tb values(1) insert into tb values(3)gocreate proc my_proc @id int OUTPUT as begin if not exists (select 1 from tb) set @id = 1 else begin select @id = min(m.px) + 1 from (select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) m, (select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) n where m.id <> n.id - 1 and m.px = n.px - 1 if @id is null select @id = max(id) + 1 from tb end
end godeclare @id as intexec my_proc @id outputselect @iddrop table tb drop proc my_proc/*
----------- 2 (所影响的行数为 1 行) */--这是不存在断号时. create table tb(id int) insert into tb values(1) insert into tb values(2)gocreate proc my_proc @id int OUTPUT as begin if not exists (select 1 from tb) set @id = 1 else begin select @id = min(m.px) + 1 from (select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) m, (select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) n where m.id <> n.id - 1 and m.px = n.px - 1 if @id is null select @id = max(id) + 1 from tb end
end godeclare @id as intexec my_proc @id outputselect @iddrop table tb drop proc my_proc/*
----------- 3 (所影响的行数为 1 行) */
取消自增属性 --创建测试表 CREATE TABLE t1(ID int IDENTITY,A int) GO --插入记录 INSERT t1 VALUES(1) GO--1. 将IDENTITY(标识)列变为普通列 ALTER TABLE t1 ADD ID_temp int GOUPDATE t1 SET ID_temp=ID ALTER TABLE t1 DROP COLUMN ID EXEC sp_rename N't1.ID_temp',N'ID',N'COLUMN' INSERT t1 VALUES(100,9) GO--2. 将普通列变为标识列 CREATE TABLE t1_temp(ID int,A int IDENTITY) SET IDENTITY_INSERT t1_temp ON INSERT t1_temp(ID,A) SELECT * FROM t1 SET IDENTITY_INSERT t1_temp OFF DROP TABLE T1 GOEXEC sp_rename N't1_temp',N't1' INSERT t1 VALUES(109999) GO--显示处理结果 SELECT * FROM t1 /*--结果: ID A ----------------- ----------- 1 1 100 9 109999 10 --*/
--以下三段,存储过程一样,只是显示不同数据时的情况.
--这是没有数据时.
create table tb(id int)
gocreate proc my_proc @id int OUTPUT
as
begin
if not exists (select 1 from tb)
set @id = 1
else
begin
select @id = min(m.px) + 1 from
(select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) m,
(select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) n
where m.id <> n.id - 1 and m.px = n.px - 1
if @id is null
select @id = max(id) + 1 from tb
end
end
godeclare @id as intexec my_proc @id outputselect @iddrop table tb
drop proc my_proc/*
-----------
1(所影响的行数为 1 行)
*/--这是存在断号时.create table tb(id int)
insert into tb values(1)
insert into tb values(3)gocreate proc my_proc @id int OUTPUT
as
begin
if not exists (select 1 from tb)
set @id = 1
else
begin
select @id = min(m.px) + 1 from
(select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) m,
(select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) n
where m.id <> n.id - 1 and m.px = n.px - 1
if @id is null
select @id = max(id) + 1 from tb
end
end
godeclare @id as intexec my_proc @id outputselect @iddrop table tb
drop proc my_proc/*
-----------
2
(所影响的行数为 1 行)
*/--这是不存在断号时.
create table tb(id int)
insert into tb values(1)
insert into tb values(2)gocreate proc my_proc @id int OUTPUT
as
begin
if not exists (select 1 from tb)
set @id = 1
else
begin
select @id = min(m.px) + 1 from
(select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) m,
(select * , px = (select count(1) from tb where id < t.id) + 1 from tb t) n
where m.id <> n.id - 1 and m.px = n.px - 1
if @id is null
select @id = max(id) + 1 from tb
end
end
godeclare @id as intexec my_proc @id outputselect @iddrop table tb
drop proc my_proc/*
-----------
3
(所影响的行数为 1 行)
*/
--创建测试表
CREATE TABLE t1(ID int IDENTITY,A int)
GO
--插入记录
INSERT t1 VALUES(1)
GO--1. 将IDENTITY(标识)列变为普通列
ALTER TABLE t1 ADD ID_temp int
GOUPDATE t1 SET ID_temp=ID
ALTER TABLE t1 DROP COLUMN ID
EXEC sp_rename N't1.ID_temp',N'ID',N'COLUMN'
INSERT t1 VALUES(100,9)
GO--2. 将普通列变为标识列
CREATE TABLE t1_temp(ID int,A int IDENTITY)
SET IDENTITY_INSERT t1_temp ON
INSERT t1_temp(ID,A) SELECT * FROM t1
SET IDENTITY_INSERT t1_temp OFF
DROP TABLE T1
GOEXEC sp_rename N't1_temp',N't1'
INSERT t1 VALUES(109999)
GO--显示处理结果
SELECT * FROM t1
/*--结果:
ID A
----------------- -----------
1 1
100 9
109999 10
--*/