数据库表的基本信息，你知道吗？

用SQL Doc生成数据库字典文档的时候，突然发现有字段描叙(Description)这项内容,以前一直没有注意过，故特意研究了一下,结果越挖越深，就写了这篇文章。

以前在做数据库脚本开发时，新建表时，对各个字段的描叙要么是记录在文档里面，要么自己建一个表，来保存这些内容，以便日后开发、维护的方便。其实这些信息完全可以放在数据库自己的系统视图里面。

对字段的说明、描述一般都放在系统视图sys.extended_properties中，例如(表dbo.Employee的字段Department的说明)

SELECT   *   FROM  dbo.Employee
SELECT   *   FROM  sys.extended_properties 

 

其中 当class =1时，major_id它的值是dbo.Employee的id，minor_id是Department的id(详细信息参见MSDN)，如下图所示

 

SELECT   OBJECT_ID (N ' dbo.Employee ' )

SELECT   column_id  FROM     sys.columns
WHERE     object_id   =   OBJECT_ID ( ' dbo.Employee ' )
         AND  name  =   ' Department '

 

 

其实在MSSMS 管理器中，选中要添加字段说明的表，单击右键——》修改（08是设计），如下图所示，增加后，保存。就会在sys.extended_properties里添加相应的记录。

 

当然你也可以用脚本命令添加数据库表的字段说明

EXEC  sp_addextendedproperty N ' MS_Description ' , N ' 雇员名称 ' ,  ' SCHEMA ' , N ' dbo ' ,  ' TABLE ' , N ' Employee ' ,  ' COLUMN ' , N ' EmployeeName '

 

 

如果已经存在刚才记录，你再执行上面这段脚本，就会提示：

消息  15233 ，级别  16 ，状态  1 ，过程 sp_addextendedproperty，第  38  行
无法添加属性。 ' dbo.Employee.EmployeeName '  已存在属性  ' MS_Description ' 。

 

下面看看工具生成的文档，工具生成这些信息肯定是数据库里存有对象的这些信息，下面我们来看看这些信息都是从何而来吧

 这里先列举一些保存表信息的系统表、视图吧，可能有些遗漏了，实在太多了，要仔细把这些全部列举出来还得花费一番功夫

代码

SELECT   *   FROM  sys.columns

-- 为每个表和视图中的每列返回一行，并为数据库中的存储过程的每个参数返回一行。
SELECT   *   FROM  syscolumns

-- 每个表对象的信息
SELECT   *   FROM  sys.tables

SELECT   *   FROM  sysobjects

-- 在数据库中创建的每个用户定义的架构范围内的对象的信息
SELECT   *   FROM  sys.objects

-- 数据库实例中的每个数据库的信息
SELECT   *   FROM  sys.databases

-- 系统数据类型
SELECT   *   FROM  sys.types

-- 含数据库中每个视图、规则、默认值、触发器、CHECK 约束、DEFAULT 约束和存储过程的项
SELECT   *   FROM  dbo.syscomments

-- 保存表的自增列信息
SELECT   *   FROM  sys.identity_columns

 

 

下面来看看属性那栏的信息保存在那些表里面。如果表是数据库的默认排序规则，就可以用下面脚本。

代码

SELECT   create_date  AS Created ,
        modify_date  AS Last Modified,
        (  SELECT     collation_name
           FROM       sys.databases
           WHERE      name  =   ' MyAssistant '
        )  AS  collation_name
FROM     SYS.tables
WHERE    NAME  =   ' Employee '

 

如果用某个列的排序规则可用下面的脚本

代码

SELECT   create_date   AS  Created,
        modify_date   AS  Last Modified,
        (  SELECT   DISTINCT
                    collation
           FROM       syscolumns
           WHERE      id  =   OBJECT_ID (N ' dbo.Employee ' )
                     AND  collation  IS   NOT   NULL
                     AND  name  = ' EmployeeName '
        )  AS  collation_name
FROM     sys.tables
WHERE    NAME  =   ' Employee '

 

查看数据库的排序规则可以从  sys.databases查看，而表的某个列的排序规则信息保存在syscolumns里面。上图的Heap， Row Count信息我还不知是从哪里来的。

接下来看看Cloumns信息吧

代码

SELECT  
    C.Name  AS  FieldName,
    T.Name  AS  DataType,
     CASE   WHEN  C.Max_Length  =   - 1   THEN   ' Max '   ELSE   CAST (C.Max_Length  AS   VARCHAR )  END   AS  Max_Length,
     CASE   WHEN  C.is_nullable  =   0   THEN   ' × '    ELSE   ' √ '   END   AS  Is_Nullable,
    C.is_identity,
     ISNULL (M. text ,  '' )   AS   DefaultValue,
     ISNULL (P.value,  '' )  AS  FieldComment
    
FROM  sys.columns  C
INNER   JOIN   sys.types T  ON  C.system_type_id  =  T.user_type_id
LEFT   JOIN  dbo.syscomments M  ON  M.id  =  C.default_object_id
LEFT    JOIN  sys.extended_properties P  ON  P.major_id  =  C. object_id   AND  C.column_id  =  P.minor_id 
WHERE  C. [ object_id ]   =   OBJECT_ID ( ' dbo.Employee ' )
ORDER   BY  C.Column_Id  ASC

 

如图所示，得到结果与文档还是有些区别，我通过该脚本实现与文档一致的时候，怎么也找不到nvarchar(30)的30，这个值的出处，后来才发现它其实就是nvarchar的max_length 的一半。

 

修改脚本如下所示 

代码

SELECT  
    C.Name  AS  FieldName,
     CASE   WHEN  T.Name  = ' nvarchar '   THEN  
              T.name  + ' ( '   +   CAST (C.max_length / 2   AS   VARCHAR )  + ' ) '  
          ELSE  T.name  END   AS  DataType,
     CASE   WHEN  C.Max_Length  =   - 1   THEN   ' Max '   ELSE   CAST (C.Max_Length  AS   VARCHAR )  END   AS  Max_Length,
     CASE   WHEN  C.is_nullable  =   0   THEN   ' × '    ELSE   ' √ '   END   AS  Is_Nullable,
     ISNULL ( CAST (I.seed_value  AS   VARCHAR )  +   ' - '   +   CAST (I.increment_value  AS   VARCHAR ),  '' )  AS  is_identity,
     ISNULL (M. text ,  '' )   AS   DefaultValue,
     ISNULL (P.value,  '' )  AS  FieldComment
    
FROM  sys.columns  C
INNER   JOIN   sys.types T  ON  C.system_type_id  =  T.user_type_id
LEFT    JOIN   dbo.syscomments M  ON  M.id  =  C.default_object_id
LEFT    JOIN   sys.extended_properties P  ON  P.major_id  =  C. object_id   AND  C.column_id  =  P.minor_id 
LEFT    JOIN   sys.identity_columns I  ON  I.column_id =  C.column_id  AND  C. object_id   =  I. object_id
WHERE  C. [ object_id ]   =   OBJECT_ID ( ' dbo.Employee ' )
ORDER   BY  C.Column_Id  ASC

 

 

接下来看看Perssion信息来自何处。 首先我们来看看赋与、收回权限的脚本（我是在sa账号下运行的）

代码

DENY    SELECT   ON   [ dbo ] . [ Employee ]   TO   [ Kerry ]
GO

GO
DENY   DELETE   ON   [ dbo ] . [ Employee ]   TO   [ Kerry ]
GO

REVOKE   DELETE   ON   [ dbo ] . [ Employee ]   TO   [ Kerry ]
GO

REVOKE   SELECT   ON   [ dbo ] . [ Employee ]   TO   [ Kerry ]
GO  

 

那么这些权限信息保存在那个系统表或系统视图中，我查了很多资料，还是没有查到，呵呵，希望有知道的告诉一声。但是可以同过系统函数和系统存储过程得到一些相关的权限设置信息。

1：系统存储过程 sp_table_privileges， 它返回指定的一个或多个表的表权限（如 INSERT、DELETE、UPDATE、SELECT、REFERENCES）的列表，表具体参见（MSDN）。 

2：系统函数 fn_my_permissions 返回有效授予主体对安全对象的权限的列表，表具体参见（MSDN）

EXEC  sp_table_privileges  @table_name   =   ' Employee ' ;

EXEC  sp_table_privileges  @table_name   = ' Employee '  ,  @table_owner   = ' dbo '

  

 

SELECT   *  
FROM  fn_my_permissions( ' dbo.Employee ' ,  ' OBJECT ' ) 
ORDER   BY  subentity_name, permission_name ; 

 

 

-- 查看用户Kerry的有效权限
SELECT   *   FROM  fn_my_permissions( ' Kerry ' ,  ' USER ' );

 

再来看看SQL Srcipt，好像没有那个系统表、系统视图保存创建表的脚本（如果有的话，算我孤陋寡闻了），也不能通过SP_HELPTEXT来得到（存储过程可以），在

网上搜索了下大概有SMO 方式和存储过程来实现的，SMO方式我还没来得及验证，存储过程倒是找到一个（本来打算自己尝试下的。呵呵，那这篇文章得耗上好长时间了，等写完了，自己再写个试试），下面的存储过程是我在http://edu.codepub.com/2009/0603/5408.php这里搜索到，也不知道原创作者是谁。

 

代码

If   object_id ( ' up_CreateTable ' )  Is   Not   Null
     Drop   Proc  up_CreateTable
Go
/*  生成建表脚本(V2.0)  OK_008 2009-5-18  */
Create   Proc  up_CreateTable
(
     @objectList   nvarchar ( max ) = null
)
-- With ENCRYPTION
As
/*   参数说明：
    @objectList 对象列表，对象之间使用","隔开
    
    改存储过程生成的建表脚本，包含Column,Constraint,Index
*/
Set  Nocount  On
     Declare   @sql   nvarchar ( max ),
             @objectid   int ,
             @id   int ,
             @Rowcount   int ,
             @ObjectName  sysname,
             @Enter   nvarchar ( 2 ),
             @Tab   nvarchar ( 2 )

     Select       @Enter = Char ( 13 ) + Char ( 10 ),
             @Tab = Char ( 9 )    

     Declare   @Tmp   Table (name sysname)
    
     If   @objectList > ''
     Begin
         Set   @sql = ' Select N ''' + Replace ( @objectList , ' , ' , '''  Union All Select N ''' ) + ''''
         Insert   Into   @Tmp  (name)  Exec ( @sql )

         Set   @sql = null
         Select   @sql = Isnull ( @sql + ' , ' , '' ) + name 
             From   @Tmp   As  a
             Where   Not   Exists ( Select   1   From  sys.objects  Where  type = ' U '   And  name = a.name)

         If   @sql > ''
         Begin
             Set   @sql = ' 发现无效的表名:  ' + @sql
             Raiserror   50001   @sql
             Return ( 1 )
         End
     End

     If   object_id ( ' tempdb..#Objects ' )  Is   Not   Null
         Drop   Table  #Objects
    
     If   object_id ( ' tempdb..#Columns ' )  Is   Not   Null
         Drop   Table  #Columns    
    
     Create   Table  #Objects(id  int   Identity ( 1 , 1 )  Primary   Key , object_id   int ,name sysname)

     
    ; With  t  As  
    (
     Select   Object_id , Convert ( int , 0 )  As  LevelNo,name  As   object_name
             From  sys.objects a 
             Where  Type = ' U '   And  is_ms_shipped = 0   And   Not   Exists ( Select   1   From  sys.foreign_keys  Where  referenced_object_id = a. object_id )
     Union   All
     Select  a.referenced_object_id  As   Object_id ,b.LevelNo + 1   As  LevelNo,c.name  As   object_name
         From  sys.foreign_keys a 
             Inner   Join  t b  On  b. object_id = a.parent_object_id
             Inner   Join  sys.objects c  On  c. object_id = a.referenced_object_id  And  c.is_ms_shipped = 0
    )
     Insert   Into  #Objects( object_id ,name)
         Select  a. object_id , object_name
             From  t a
             Where      Not   Exists ( Select   1   From  t  Where   object_id = a. object_id   And  LevelNo > a.LevelNo)  And
                     Not   Exists ( Select   1   From  sys.extended_properties  Where  major_id = a. object_id   And  minor_id = 0   And  class = 1   And  Name = N ' microsoft_database_tools_support ' )
                     And  ( Exists ( Select   1   From   @Tmp   Where  name = a. object_name )  Or   Not   Exists ( Select   1   From   @Tmp ))
             Group   By   object_id , object_name ,LevelNo
             Order   By  LevelNo  Desc

     Set   @Rowcount = @@Rowcount
     If   @Rowcount = 0
     Begin
         Raiserror   50001  N ' 没有可以生产脚本的表! '
         Return ( 1 )
     End

     -- Column
     Select     a. object_id ,
            a.column_id  As  Seq,
             Cast ( 1   As   tinyint )  As  DefinitionType,
             Quotename (a.name) + Char ( 32 ) +  c.name  +
             Case  
                 When  a.user_type_id  In  ( 231 , 239 )  Then   ' ( ' + Case  a.max_length  When   - 1   Then   ' Max '   Else   Rtrim (a.max_length / 2 )  End   + ' ) '
                 When  a.user_type_id  In  ( 62 , 165 , 167 , 173 , 175 )  Then   ' ( ' + Case  a.max_length  When   - 1   Then   ' Max '   Else   Rtrim (a.max_length)  End + ' ) '
                 When  a.user_type_id  In  ( 106 , 108 )  Then   ' ( ' + Rtrim (a. [ precision ] ) + ' , ' + Rtrim (a.scale) + ' ) '  
                 Else   ''
             End
             +   Char ( 32 ) +
             Case  a.is_rowguidcol  When   1   Then   ' Rowguidcol  '   Else   ''   End   +
             Case  a.is_identity  When   1   Then   ' Identity( ' + Cast (d.seed_value  As   nvarchar ( 10 )) + ' , ' + Cast (d.increment_value  As   nvarchar ( 10 )) + ' )  '   Else   ''   End +  
             Case  a.is_nullable  When   1   Then   ' Null  '   Else   ' Not Null  '   End +
             Isnull ( ' Constraint  ' + Quotename (e.name) + '  Default( ' + e.definition + ' ) ' , '' )  As  definition

             Into  #Columns
         From  sys.columns  As  a
             Inner   Join  #Objects  As  b  On  b. object_id = a. object_id
             Inner   Join  sys.types  As  c  On  c.user_type_id = a.user_type_id
             Left   Outer   Join  sys.identity_columns  As  d  On  d. object_id = a. object_id   And  d.column_id = a.column_id  And  a.is_identity = 1
             Left   Outer   Join  sys.Default_constraints  As  e  On  e. object_id = a.default_object_id  And  e.parent_column_id = a.column_id

         Create   Nonclustered   Index  IX_#Columns_object_id  On  #Columns( object_id   Asc )

         -- Constraint
         Insert   Into  #Columns
    
         Select     a.parent_object_id  As   object_id ,
                Row_number()  Over (Partition  By  a.parent_object_id  Order   By   Case  a.type  When   ' PK '   Then   1   When   ' C '   Then   2   Else   3   End ) As  Seq,
                 2   As  DefinitionType,
                 ' Alter Table  ' + Quotename ( object_name (a.parent_object_id))  + '  Add Constraint  ' + Quotename (a.name) +
                 Case  a.type 
                     When   ' PK '   Then   '  Primary Key  ' + Case   When   Exists ( Select   1   From  sys.indexes  Where   object_id = a.parent_object_id  And  is_primary_key = 1   And  type = 1 )  Then  N ' Clustered  '   Else  N ' Nonclustered  '   End +
                                                 ' ( ' + Stuff (( Select   ' , ' + Quotename (c1.Name) + Case  a1.is_descending_key  When   1   Then   '  Desc '   Else   '  Asc '   End
                                                         From  sys.index_columns  As  a1
                                                             Inner   Join  sys.indexes  As  b1  On  b1. object_id = a1. object_id   And  b1.index_id = a1.index_id  And  b1.is_primary_key = 1
                                                             Inner   Join  sys.columns  As  c1  On  c1. object_id = a1. object_id   And  c1.column_id = a1.column_id
                                                         Where  a1. object_id = a.parent_object_id 
                                                         For  Xml Path( '' )
                                                    ), 1 , 1 , '' ) +
                                                 ' ) '
                     When   ' F '   Then   '  Foreign Key ( ' + Stuff (( Select   ' , ' + Quotename (b1.Name)
                                                         From  sys.foreign_key_columns  As  a1
                                                             Inner   Join  sys.columns  As  b1  On  b1. object_id = a1.parent_object_id  And  b1.column_id = a1.parent_column_id
                                                         Where  a1.constraint_object_id = a. object_id  
                                                         Order   By  a1.constraint_column_id
                                                         For  Xml Path( '' )
                                                    ), 1 , 1 , '' ) +
                                                 ' ) References  ' + ( Select   Quotename ( object_name (referenced_object_id))  From   sys.foreign_keys  Where   object_id = a. object_id ) +
                                                 '  ( '
                                                     + Stuff (( Select   ' , ' + Quotename (b1.Name)
                                                         From  sys.foreign_key_columns  As  a1
                                                             Inner   Join  sys.columns  As  b1  On  b1. object_id = a1.referenced_object_id  And  b1.column_id = a1.referenced_column_id
                                                         Where  a1.constraint_object_id = a. object_id  
                                                         Order   By  a1.constraint_column_id
                                                         For  Xml Path( '' )
                                                    ), 1 , 1 , '' ) +
                                                 ' ) '
                     When   ' UQ '   Then   '  Unique ' + ( Select   Case  a1.type  When   1   Then   '  Clustered '   Else   '  Nonclustered '   End
                                                     From  sys.indexes  As  a1
                                                     Where  a1. object_id = a.parent_object_id 
                                                                 And   Exists ( Select   1   From  sys.key_constraints  Where   object_id = a. object_id   And  parent_object_id = a1. object_id   And  unique_index_id = a1.index_id)
                                               ) +                         
                                                 ' ( ' + Stuff (( Select   ' , ' + Quotename (c1.Name) + Case  a1.is_descending_key  When   1   Then   '  Desc '   Else   '  Asc '   End
                                                         From  sys.index_columns  As  a1
                                                             Inner   Join  sys.indexes  As  b1  On  b1. object_id = a1. object_id   And  b1.index_id = a1.index_id  And  b1.is_unique_constraint = 1
                                                             Inner   Join  sys.columns  As  c1  On  c1. object_id = a1. object_id   And  c1.column_id = a1.column_id
                                                         Where  a1. object_id = a.parent_object_id 
                                                                 And   Exists ( Select   1   From  sys.key_constraints  Where   object_id = a. object_id   And  parent_object_id = a1. object_id   And  unique_index_id = a1.index_id)
                                                         For  Xml Path( '' )
                                                    ), 1 , 1 , '' ) +
                                                 ' ) '
                     When   ' C '   Then   '  Check '   + ( Select  definition  From  sys.check_constraints  Where   object_id = a. object_id )
                     Else   ''
                 End   As  definition

             From  sys.objects  As  a
             Where  a.type  In ( ' PK ' , ' F ' , ' C ' , ' UQ ' )
                     And   Exists ( Select   1    From  #Objects  Where   object_id = a.parent_object_id)

         -- Index
         Insert   Into  #Columns
         Select     a. object_id  ,
                a.index_id  As  Seq,
                 3   As  DefinitionType,
                 ' Create  ' + Case  a.is_unique  When   1   Then   ' Unique  '   Else   ''   End +
                 Case  a.type  When   1   Then   ' Clustered  '   Else   ' Nonclustered  '   End +
                 ' Index  ' + Quotename (a.name) + '  On  ' + Quotename (b.name) +
                                         '  ( ' + Stuff (( Select   ' , ' + Quotename (b1.Name) + Case  a1.is_descending_key  When   1   Then   '  Desc '   Else   '  Asc '   End
                                                         From  sys.index_columns  As  a1
                                                             Inner   Join  sys.columns  As  b1  On  b1. object_id = a1. object_id   And  b1.column_id = a1.column_id
                                                         Where  a1. object_id = a. object_id   And  a.index_id = a1.index_id  And  a1.is_included_column = 0
                                                         For  Xml Path( '' )
                                                    ), 1 , 1 , '' ) +
                                         ' ) ' +
                                         Isnull ( '  Include( ' + Stuff (( Select   ' , ' + Quotename (b1.Name)
                                                         From  sys.index_columns  As  a1
                                                             Inner   Join  sys.columns  As  b1  On  b1. object_id = a1. object_id   And  b1.column_id = a1.column_id
                                                         Where  a1. object_id = a. object_id   And  a.index_id = a1.index_id  And  a1.is_included_column = 1
                                                         For  Xml Path( '' )
                                                    ), 1 , 1 , '' ) +
                                         ' ) ' , '' )
                     As  definition
             From  sys.indexes  As  a
                 Inner   Join  #Objects  As  b  On  b. object_id = a. object_id
             Where  a.type > 0
                     And   Not   Exists ( Select   1   From  sys.key_constraints  Where  parent_object_id = a. object_id   And  unique_index_id = a.index_id)

        

         -- Print
        

         Print   ' Use  ' + Quotename ( db_name ()) + @Enter + ' Go ' + @Enter + ' /* 创建表结构 Andy  ' + Convert ( nvarchar ( 10 ), Getdate (), 120 ) + ' */ ' + @Enter

         Set   @id = 1
         While   @id <= @Rowcount
         Begin
             Select   @objectid = object_id , @ObjectName = name  From  #Objects  Where  id = @id

             Set   @Sql = @Enter + ' --( ' + Rtrim ( @id ) + ' / ' + Rtrim ( @Rowcount ) + ' )  ' + @ObjectName + @Enter + ' If object_id( ''' + Quotename ( @ObjectName ) + ''' ) Is Null ' + @Enter + ' Begin ' + @Enter + @Tab +
                     ' Create Table  ' + Quotename ( @ObjectName ) + @Enter + @Tab + ' ( ' + @Enter
             Select   @Sql = @Sql + @Tab + @Tab + definition + ' , ' + @Enter
                 From  #Columns 
                 Where   object_id = @objectid  
                         And  DefinitionType = 1
                 Group   By  Seq,definition
                 Order   By  Seq
             Set   @sql = Substring ( @sql , 1 , Len ( @sql ) - 3 ) + @Enter + @Tab + ' ) ' + @Enter
             Select   @Sql = @Sql + @Tab + definition + @Enter
                 From  #Columns 
                 Where   object_id = @objectid  
                         And  DefinitionType > 1
                 Group   By  DefinitionType,Seq,definition
                 Order   By  Seq

             Print   Substring ( @sql , 1 , Len ( @sql ) - 2 ) + @Enter + ' End '
             Set   @id = @id + 1
         End

         Print   ' Go '

     Drop   Table  #Columns
     Drop   Table  #Objects
Go