一.查旬乙個表有哪些主鍵：
(1)exec sp_pkeys @table_name='表名'
可以按資料庫中表的順序顯示
(2)select table_name,column_name from information_schema.key_column_usage
where table_name='表名'
(3)查詢資料庫中所有表的主鍵
select o.name as 表名,c.name as 欄位名,k.colid as 字段序號,k.keyno as 索引順序 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
where o.xtype = 'u'
and exists(select 1 from sysobjects where xtype = 'pk' and name = i.name)
order by o.name,k.colid
(4) exec sp_helpconstraint '表名'
二.查詢乙個表有哪些外來鍵：
(1)select object_name(a.parent_object_id) 'tables'
from sys.foreign_keys a
where a.referenced_object_id=object_id('表名')
(2)select * from sysforeignkeys 獲取表外來鍵
三.查詢表結構資訊
（1）sp_help n'表名'
（2）select (case when a.colorder=1 then d.name else null end) 表名,
a.colorder 字段序號,a.name 欄位名,
(case when columnproperty( a.id,a.name,'isidentity')=1 then '√'else '' end) 標識,
(case when (select count(*) from sysobjects
where (name in (select name from sysindexes
where (id = a.id) and (indid in
(select indid from sysindexkeys
where (id = a.id) and (colid in
(select colid from syscolumns where (id = a.id) and (name = a.name)))))))
and (xtype = 'pk'))>0 then '√' else '' end) 主鍵,b.name 型別,a.length 占用位元組數,
columnproperty(a.id,a.name,'precision') as 長度,
isnull(columnproperty(a.id,a.name,'scale'),0) as 小數字數,(case when a.isnullable=1 then '√'else '' end) 允許空,
isnull(e.text,'') 預設值,isnull(g.[value], ' ') as [說明]
from syscolumns a
left join systypes b on a.xtype=b.xusertype
inner join sysobjects d on a.id=d.id and d.xtype='u' and d.name<>'dtproperties'
left join syscomments e on a.cdefault=e.id
left join sys.extended_properties g on a.id=g.major_id and a.colid=g.minor_id
left join sys.extended_properties f on d.id=f.class and f.minor_id=0
--where b.name is not null
where d.name='表名' --如果只查詢指定表,加上此條件
order by a.id,a.colorder
四.獲取表字段資訊
(1)select syscolumns.name,systypes.name,syscolumns.isnullable, syscolumns.length
from syscolumns, systypes
where syscolumns.xusertype = systypes.xusertype and syscolumns.id = object_id('表名')
五.查詢某個資料庫中所有的表名：
(1)select name from sysobjects where xtype='u' order by name
六.查詢資料庫中的所有資料庫名
(1)select name from master..sysdatabases order by name
七.重建主鍵批處理
1.刪除主鍵：
declare @pk varchar(100);
select @pk=name from sysobjects where parent_obj=object_id('表名') and xtype='pk';
if @pk is not null
begin
exec('alter table abcd drop '+ @pk) --刪除原主鍵
end2.把所有主鍵設為不能為空
alter table abcd alter column c char(10) not null
3.重建主鍵：
alter table abcd add constraint pk_abcd primary key (a, b, c )
查詢資料庫中沒有主鍵的表名並為其增加主鍵的方法:
declare @tablename sysname
declare @strsql nchar(500)
declare tablenamecursor cursor for
select b.name from sysobjects b where xtype='u' and b.name not in
(select object_name(a.parent_obj) from sysobjects a where xtype='pk' )
open tablenamecursor
fetch next from tablenamecursor into @tablename
while @@fetch_status = 0
begin
print @tablename
set @strsql= 'alter table ' + @tablename + ' add primary key (id) '
print @strsql
exec (@strsql)
fetch next from tablenamecursor into @tablename
end
close tablenamecursor
deallocate tablenamecursor
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