利用触发器实现标识列连续。(支持批量插入) if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[ttt]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [dbo].[ttt] GO/****** Object: Table [dbo].[ttt] Script Date: 2008-12-15 17:11:26 ******/ CREATE TABLE [dbo].[ttt] ( [id] [int] IDENTITY (1, 1) NOT NULL , [name] [varchar] (50) COLLATE Chinese_PRC_CI_AS NULL , [time] [datetime] NULL ) ON [PRIMARY] GOALTER TABLE [dbo].[ttt] ADD CONSTRAINT [PK_ttt] PRIMARY KEY CLUSTERED ( [id] ) ON [PRIMARY] GOinsert into ttt(name,time) values('logan',getdate()); insert into ttt(name,time) values('peter',getdate()); insert into ttt(name,time) values('man',getdate()); insert into ttt(name,time) values('lida',getdate()); insert into ttt(name,time) values('fcuandy',getdate());select * from ttt /* 1 logan 2008-12-15 17:36:37.780 2 peter 2008-12-15 17:36:37.780 3 man 2008-12-15 17:36:37.780 4 lida 2008-12-15 17:36:37.780 5 fcuandy 2008-12-15 17:36:37.793 */ GO CREATE TRIGGER tr ON ttt INSTEAD OF INSERT AS SET IDENTITY_INSERT ttt ON DECLARE @n INT SELECT @n=MAX(id) FROM ttt ;WITH fc AS ( SELECT n=1 UNION ALL SELECT nn=n+1 FROM fc WHERE n<@n ),fc1 AS ( SELECT n FROM fc a LEFT JOIN ttt b ON a.n = b.id WHERE b.id IS NULL ) INSERT ttt(id,name,time) SELECT n,name,time FROM (SELECT ROW_NUMBER() OVER (ORDER BY GETDATE()) idx,n FROM fc1) a INNER JOIN ( SELECT idx=ROW_NUMBER() OVER (ORDER BY GETDATE()),name,time FROM inserted ) b ON a.idx=b.idx DECLARE @r INT SELECT @r=@@ROWCOUNT
SET IDENTITY_INSERT ttt OFF INSERT ttt(name,time) SELECT name,time FROM ( SELECT idx=ROW_NUMBER() OVER (ORDER BY GETDATE()),name,time FROM inserted ) x WHERE idx>@r GO DELETE FROM ttt WHERE name = 'peter' OR name='lida' GO INSERT ttt SELECT 'xxx',getdate() INSERT ttt SELECT 'yyy',GETDATE() GO SELECT * FROM ttt /* 1 logan 2008-12-15 17:37:20.967 2 xxx 2008-12-15 17:37:21.013 3 man 2008-12-15 17:37:20.967 4 yyy 2008-12-15 17:37:21.030 5 fcuandy 2008-12-15 17:37:20.967 */DELETE FROM ttt WHERE name ='xxx' OR name='yyy'INSERT ttt SELECT 'roy_88',GETDATE() UNION ALL SELECT 'limpire',GETDATE() UNION ALL SELECT '熊',GETDATE()SELECT * FROM ttt/* 1 logan 2008-12-15 17:38:29.450 2 roy_88 2008-12-15 17:38:29.530 3 man 2008-12-15 17:38:29.467 4 limpire 2008-12-15 17:38:29.530 5 fcuandy 2008-12-15 17:38:29.467 6 熊 2008-12-15 17:38:29.530 */ 本文来自CSDN博客,转载请标明出处:http://blog.csdn.net/fcuandy/archive/2008/12/15/3522876.aspx
数据表中有一列,作为标识,自增,通常还作为主键,在一对多关系中作为主表的关键字段与从表相连接,因此,通常情况下,作为主键的列的值是不轻易改动的. 举个最简单的例子,现在学生上大学的时候,进校之前,学校就给排了学号,这个学号就是一个主键,如果某个新生没有来学校报到,而他的学号又不是最后一个,那必定会在中间空出一个来,但是,即使有这样的情况,学号在其后的学生学号,决不会向前递减改成新号.因为,那可能会引起系统混乱.主键列是一个标识,并不需要连续,正如学生的学号可以不连续一样,不连续,又有什么关系呢? 如果表中的标识列不连接,而你有时候又要用到连续的排序怎么办呢?那就可以通过产生序号来解决.在MSSQL里产生连续的序号很简单,一个函数就搞定了,ACCESS里也有办法,比如: select *,(select count(*) from tb where id<=a.id)as rn from tb a 就能产生一个连续的序号.学习数据库,要能习惯于不连续的标识列.
//删除数据 private void Del_Data() { int i = DataGridView1.Rows.Count; for (i = 0; i <= DataGridView1.Rows.Count - 1; i++) { if (DataGridView1.Rows(i).Selected) { Del_Record_DataBase(DataGridView1.Rows(i).Cells(0).Value); i = DataGridView1.Rows.Count + 1; } } } private void Del_Record_DataBase(string id) { OleDbConnection plConn = new OleDbConnection(strCon); plConn.Open(); string strDele = "DELETE FROM pl WHERE xh= " + id.Trim() + ""; OleDbCommand plCommand = new OleDbCommand(strDele, plConn); //从数据库中删除指定记录 plCommand.ExecuteNonQuery(); plConn.Close(); //更新datagridview Bind_Data(); }这是我的,该如何修改才能使得序号相连呢?
退出上面修改的模块后,在主界面的datagridview显示出来,新的序号,从1~n
楼主用的是access2010数据库,不是sql server 不过改id主键列使其连续真的没必要
无需修改序号,中间缺的会有影响吗?如果重新命名序号的话,建议用row_number()函数生成。
不需要修改数据库,只需要在datagridview做处理,跟数据库无关
具体怎么用row_nueber()函数呢
执行这样的查询语句: select xh=row_number()over(order by id),* from pl
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[ttt]') and OBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[ttt]
GO/****** Object: Table [dbo].[ttt] Script Date: 2008-12-15 17:11:26 ******/
CREATE TABLE [dbo].[ttt] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[name] [varchar] (50) COLLATE Chinese_PRC_CI_AS NULL ,
[time] [datetime] NULL
) ON [PRIMARY]
GOALTER TABLE [dbo].[ttt] ADD
CONSTRAINT [PK_ttt] PRIMARY KEY CLUSTERED
(
[id]
) ON [PRIMARY]
GOinsert into ttt(name,time) values('logan',getdate());
insert into ttt(name,time) values('peter',getdate());
insert into ttt(name,time) values('man',getdate());
insert into ttt(name,time) values('lida',getdate());
insert into ttt(name,time) values('fcuandy',getdate());select * from ttt
/*
1 logan 2008-12-15 17:36:37.780
2 peter 2008-12-15 17:36:37.780
3 man 2008-12-15 17:36:37.780
4 lida 2008-12-15 17:36:37.780
5 fcuandy 2008-12-15 17:36:37.793
*/
GO
CREATE TRIGGER tr ON ttt
INSTEAD OF INSERT
AS
SET IDENTITY_INSERT ttt ON
DECLARE @n INT
SELECT @n=MAX(id) FROM ttt
;WITH fc AS
(
SELECT n=1
UNION ALL
SELECT nn=n+1 FROM fc WHERE n<@n
),fc1 AS
(
SELECT n FROM fc a
LEFT JOIN ttt b
ON a.n = b.id
WHERE b.id IS NULL
)
INSERT ttt(id,name,time) SELECT n,name,time
FROM
(SELECT ROW_NUMBER() OVER (ORDER BY GETDATE()) idx,n FROM fc1) a
INNER JOIN
(
SELECT idx=ROW_NUMBER() OVER (ORDER BY GETDATE()),name,time FROM inserted
) b
ON a.idx=b.idx
DECLARE @r INT
SELECT @r=@@ROWCOUNT
SET IDENTITY_INSERT ttt OFF
INSERT ttt(name,time) SELECT name,time FROM
(
SELECT idx=ROW_NUMBER() OVER (ORDER BY GETDATE()),name,time FROM inserted
) x
WHERE idx>@r
GO
DELETE FROM ttt WHERE name = 'peter' OR name='lida'
GO
INSERT ttt SELECT 'xxx',getdate()
INSERT ttt SELECT 'yyy',GETDATE()
GO
SELECT * FROM ttt
/*
1 logan 2008-12-15 17:37:20.967
2 xxx 2008-12-15 17:37:21.013
3 man 2008-12-15 17:37:20.967
4 yyy 2008-12-15 17:37:21.030
5 fcuandy 2008-12-15 17:37:20.967
*/DELETE FROM ttt WHERE name ='xxx' OR name='yyy'INSERT ttt SELECT 'roy_88',GETDATE() UNION ALL SELECT 'limpire',GETDATE() UNION ALL SELECT '熊',GETDATE()SELECT * FROM ttt/*
1 logan 2008-12-15 17:38:29.450
2 roy_88 2008-12-15 17:38:29.530
3 man 2008-12-15 17:38:29.467
4 limpire 2008-12-15 17:38:29.530
5 fcuandy 2008-12-15 17:38:29.467
6 熊 2008-12-15 17:38:29.530
*/
本文来自CSDN博客,转载请标明出处:http://blog.csdn.net/fcuandy/archive/2008/12/15/3522876.aspx
序号是一个标识,你改了这个列的值,如果它有外键,是否也要一并修改?如果在查询的时候需要连续的序号,可以用 row_number()函数生成一个,简单得很.
数据表中有一列,作为标识,自增,通常还作为主键,在一对多关系中作为主表的关键字段与从表相连接,因此,通常情况下,作为主键的列的值是不轻易改动的.
举个最简单的例子,现在学生上大学的时候,进校之前,学校就给排了学号,这个学号就是一个主键,如果某个新生没有来学校报到,而他的学号又不是最后一个,那必定会在中间空出一个来,但是,即使有这样的情况,学号在其后的学生学号,决不会向前递减改成新号.因为,那可能会引起系统混乱.主键列是一个标识,并不需要连续,正如学生的学号可以不连续一样,不连续,又有什么关系呢?
如果表中的标识列不连接,而你有时候又要用到连续的排序怎么办呢?那就可以通过产生序号来解决.在MSSQL里产生连续的序号很简单,一个函数就搞定了,ACCESS里也有办法,比如:
select *,(select count(*) from tb where id<=a.id)as rn from tb a
就能产生一个连续的序号.学习数据库,要能习惯于不连续的标识列.
private void Del_Data()
{
int i = DataGridView1.Rows.Count;
for (i = 0; i <= DataGridView1.Rows.Count - 1; i++) {
if (DataGridView1.Rows(i).Selected) {
Del_Record_DataBase(DataGridView1.Rows(i).Cells(0).Value);
i = DataGridView1.Rows.Count + 1;
}
}
}
private void Del_Record_DataBase(string id)
{
OleDbConnection plConn = new OleDbConnection(strCon);
plConn.Open();
string strDele = "DELETE FROM pl WHERE xh= " + id.Trim() + "";
OleDbCommand plCommand = new OleDbCommand(strDele, plConn);
//从数据库中删除指定记录
plCommand.ExecuteNonQuery();
plConn.Close();
//更新datagridview
Bind_Data();
}这是我的,该如何修改才能使得序号相连呢?
退出上面修改的模块后,在主界面的datagridview显示出来,新的序号,从1~n
不过改id主键列使其连续真的没必要
具体怎么用row_nueber()函数呢
select xh=row_number()over(order by id),* from pl