SqlServer 修改主键总结

一.查旬一个表有哪些主键：
(1)EXEC sp_pkeys @table_name='表名'
可以按数据库中表的顺序显示
(2)SELECT TABLE_NAME,COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE   
   WHERE TABLE_NAME='表名'
(3)查询数据库中所有表的主键
    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 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.查询一个表有哪些外键：
(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 获取表外键    
 
三.查询表结构信息
（1）sp_help N'表名'
（2）SELECT (case when a.colorder=1 then d.name else null end) 表名,  
         a.colorder 字段序号,a.name 字段名,
        (case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end) 标识,
        (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) 主键,b.name 类型,a.length 占用字节数,  
         COLUMNPROPERTY(a.id,a.name,'PRECISION') as 长度,  
         isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0) as 小数位数,(case when a.isnullable=1 then '√'else '' end) 允许空,  
         isnull(e.text,'') 默认值,isnull(g.[value], ' ') AS [说明]
         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' --如果只查询指定表,加上此条件
         order by a.id,a.colorder

四.获取表字段信息
(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.查询某个数据库中所有的表名：
(1)SELECT Name FROM SysObjects Where XType='U' ORDER BY Name

六.查询数据库中的所有数据库名
(1)SELECT Name FROM Master..SysDatabases ORDER BY Name

七.重建主键批处理
  1.删除主键：
  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)  --删除原主键
    end
    
  2.把所有主键设为不能为空
  alter table abcd alter column c char(10) not null

  3.重建主键：
  ALTER Table abcd ADD CONSTRAINT pk_abcd   PRIMARY KEY (a, b, c )
 
 
查询数据库中没有主键的表名并为其增加主键的方法:
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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转载于:https://www.cnblogs.com/yzhming/p/4890545.html