添加表字段
alter table table1 add transactor varchar(10) not Null;
alter table table1 add id int unsigned not Null auto_increment primary key
修改某个表的字段类型及指定为空或非空
alter table 表名称 change 字段名称 字段名称 字段类型 [是否允许非空];
alter table 表名称 modify 字段名称 字段类型 [是否允许非空];
alter table 表名称 modify 字段名称 字段类型 [是否允许非空];
修改某个表的字段名称及指定为空或非空
alter table 表名称 change 字段原名称 字段新名称 字段类型 [是否允许非空
删除某一字段
ALTER TABLE mytable DROP 字段 名;
添加唯一键
ALTER TABLE `test2` ADD UNIQUE ( `userid`)
修改主键
ALTER TABLE `test2` DROP PRIMARY KEY ,ADD PRIMARY KEY ( `id` )
增加索引
ALTER TABLE `test2` ADD INDEX ( `id` )
ALTER TABLE `category ` MODIFY COLUMN `id` int(11) NOT NULL AUTO_INCREMENT FIRST ,ADD PRIMARY KEY (`id`);
修改主键的sql语句块如下:
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(www.169it.com)
declare
@defname
varchar
(100)
declare
@cmd
varchar
(500)
declare
@tablename
varchar
(100)
declare
@keyname
varchar
(100)
Set
@tablename=
'Temp1'
Set
@keyname=
'id'
--需要設置的key,分隔
select
@defname=
name
FROM
sysobjects so
JOIN
sysconstraints sc
ON
so.id = sc.constid
WHERE
object_name(so.parent_obj) = @tablename
and
xtype=
'PK'
if @defname
is
not
null
begin
select
@cmd=
'alter table '
+ @tablename+
' drop constraint '
+ @defname
--print @cmd
exec
(@cmd)
end
else
set
@defname=
'PK_'
+@keyname
select
@cmd=
'alter table '
+ @tablename+
' ADD constraint '
+ @defname +
' PRIMARY KEY CLUSTERED('
+@keyname+
')'
exec
(@cmd)
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如何取主键字段名称及字段类型--得到主键字段名
1:
SELECT TABLE_NAME,COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE TABLE_NAME<>'dtproperties'
2:
EXEC sp_pkeys @table_name='表名'
3:
select o.name as 表名,c.name as 字段名,k.colid as 字段序号,k.keyno as 索引顺序,t.name as 类型
from sysindexes i
join sysindexkeys k on i.id = k.id and i.indid = k.indid
join sysobjects o on i.id = o.id
join syscolumns c on i.id=c.id and k.colid = c.colid
join systypes t on c.xusertype=t.xusertype
where o.xtype = 'U' and o.name='要查询的表名'
and exists(select 1 from sysobjects where xtype = 'PK' and parent_obj=i.id and name = i.name)
order by o.name,k.colid