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1.新建一数据表，里面有字段id，将id设为为主键
<div class="codetitle"><a style="CURSOR: pointer" data="44465" class="copybut" id="copybut44465" onclick="doCopy('code44465')"> 代码如下:<div class="codebody" id="code44465">
create table tb(id int,constraint pkid primary key (id))
create table tb(id int primary key )
2.新建一数据表，里面有字段id，将id设为主键且自动编号
<div class="codetitle"><a style="CURSOR: pointer" data="36179" class="copybut" id="copybut36179" onclick="doCopy('code36179')"> 代码如下:<div class="codebody" id="code36179">
create table tb(id int identity(1,1),constraint pkid primary key (id))
create table tb(id int identity(1,1) primary key )
3.已经建好一数据表，里面有字段id，将id设为主键
<div class="codetitle"><a style="CURSOR: pointer" data="14153" class="copybut" id="copybut14153" onclick="doCopy('code14153')"> 代码如下:<div class="codebody" id="code14153">
alter table tb alter column id int not null
alter table tb add constraint pkid primary key (id)
4.删除主键
<div class="codetitle"><a style="CURSOR: pointer" data="53673" class="copybut" id="copybut53673" onclick="doCopy('code53673')"> 代码如下:<div class="codebody" id="code53673">
Declare @Pk varChar(100);
Select @Pk=Name from sysobjects where Parent_Obj=OBJECT_ID('tb') and xtype='PK';
if @Pk is not null
exec('Alter table tb Drop '+ @Pk)
（编辑：李大同）
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