sql系统表学习笔记
1.首先见两个表test1，test2
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[FK_test2_test1]') and OBJECTPROPERTY(id, N'IsForeignKey') = 1) ALTER TABLE [dbo].[test2] DROP CONSTRAINT FK_test2_test1 GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[test1]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [dbo].[test1] GO if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[test2]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [dbo].[test2] GO CREATE TABLE [dbo].[test1] ( [ID] [int] NOT NULL , [Name] [char] (10) COLLATE Chinese_PRC_CI_AS NULL , [bigint] [bigint] NULL , [binary] [binary] (50) NULL , [bit] [bit] NULL , [char] [char] (10) COLLATE Chinese_PRC_CI_AS NULL , [datetime] [datetime] NULL , [decimal] [decimal](18, 0) NULL , [float] [float] NULL , [image] [image] NULL , [int] [int] NULL , [money] [money] NULL , [nchar] [nchar] (10) COLLATE Chinese_PRC_CI_AS NULL , [ntext] [ntext] COLLATE Chinese_PRC_CI_AS NULL , [numeric] [numeric](18, 0) NULL , [nvarchar] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NULL , [real] [real] NULL , [smalldatetime] [smalldatetime] NULL , [smallint] [smallint] NULL , [smallmoney] [smallmoney] NULL , [sql_variant] [sql_variant] NULL , [text] [text] COLLATE Chinese_PRC_CI_AS NULL , [timestamp] [timestamp] NULL , [tinyint] [tinyint] NULL , [uniqueidentifier] [uniqueidentifier] NULL , [varbinary] [varbinary] (50) NULL , [varchar] [varchar] (50) COLLATE Chinese_PRC_CI_AS NULL ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] GO CREATE TABLE [dbo].[test2] ( [AutoID] [int] NOT NULL , [ID] [int] NULL , [remark1] [char] (10) COLLATE Chinese_PRC_CI_AS NULL , [remark2] [char] (10) COLLATE Chinese_PRC_CI_AS NULL ) ON [PRIMARY] GO ALTER TABLE [dbo].[test1] WITH NOCHECK ADD CONSTRAINT [PK_test1] PRIMARY KEY CLUSTERED ( [ID] ) ON [PRIMARY] GO ALTER TABLE [dbo].[test2] WITH NOCHECK ADD CONSTRAINT [PK_test2] PRIMARY KEY CLUSTERED ( [AutoID] ) ON [PRIMARY] GO CREATE INDEX [IX_test1] ON [dbo].[test1]([Name]) ON [PRIMARY] GO ALTER TABLE [dbo].[test2] ADD CONSTRAINT [FK_test2_test1] FOREIGN KEY ( [ID] ) REFERENCES [dbo].[test1] ( [ID] ) GO exec sp_addextendedproperty N'MS_Description', N'test1表注释', N'user', N'dbo', N'table', N'test1' GO exec sp_addextendedproperty N'MS_Description', N'ID注释', N'user', N'dbo', N'table', N'test1', N'column', N'ID' GO
2.目标：先查询一下test1表格和字段的注释
select a.value,a.*,'---------',o.*
from sysproperties a--sysproperties.value存储了表格和字段的说明
inner join sysobjects o on a.id=o.id and o.name='test1' and o.xtype='U'--id表示这个对象的编号，'U'表示这个对象的是用户表
查询结果如下： 可以看到value中不但查出了表格的注释还查询出了字段的注释而且id是一样的，说明字段和表共用一个编号，那么如何区别是表格的注释还是字段的注释呢？，乖乖，原来type字段等于3表示是表格的注释，4表示是字段的注释，我们已经把sysproperties和sysobjects全部的字段都查询出来了，但是却看不到字段的名字，查询字段对应注释就成为了下一个目标
laolaowhn
| value |
id |
smallid |
type |
name |
value |
Expr2 |
name |
id |
xtype |
uid |
info |
status |
base_schema_ver |
replinfo |
parent_obj |
crdate |
ftcatid |
schema_ver |
stats_schema_ver |
type |
userstat |
sysstat |
indexdel |
refdate |
version |
deltrig |
instrig |
updtrig |
seltrig |
category |
cache |
| test1 表注释 |
517576882 |
0 |
3 |
MS_Description |
test1 表注释 |
--------- |
test1 |
517576882 |
U |
1 |
27 |
1610615063 |
96 |
0 |
0 |
2009-9-29 16:07 |
0 |
96 |
0 |
U |
1 |
8307 |
0 |
2009-9-29 16:07 |
0 |
0 |
0 |
0 |
0 |
16904 |
0 |
| ID 注释 |
517576882 |
1 |
4 |
MS_Description |
ID 注释 |
--------- |
test1 |
517576882 |
U |
1 |
27 |
1610615063 |
96 |
0 |
0 |
2009-9-29 16:07 |
0 |
96 |
0 |
U |
1 |
8307 |
0 |
2009-9-29 16:07 |
0 |
0 |
0 |
0 |
0 |
16904 |
0 |
3.目标查询字段对应的注释：
select c.name,a.value, a.*,'________',o.*,'________',c.*
from SysProperties a --sysproperties。value存储了表格和字段的说明
inner join sysobjects o on a.id=o.id--存储了全部对象的编号名称等信息
inner join syscolumns c on a.id=c.id and a.smallid=c.colid --id表示这个对象的编号，colid表示列的编号，说明c.id还是存储了表格的编号
where o.name = 'test1'
查询结果如下：可以看到 a.smallid=c.colid把表的注释过滤掉了，
| name |
value |
id |
smallid |
type |
name |
value |
Expr3 |
name |
id |
xtype |
uid |
info |
status |
base_schema_ver |
replinfo |
parent_obj |
crdate |
ftcatid |
schema_ver |
stats_schema_ver |
type |
userstat |
sysstat |
indexdel |
refdate |
version |
deltrig |
instrig |
updtrig |
seltrig |
category |
cache |
Expr4 |
name |
id |
xtype |
typestat |
xusertype |
length |
xprec |
xscale |
colid |
xoffset |
bitpos |
reserved |
colstat |
cdefault |
domain |
number |
colorder |
autoval |
offset |
collationid |
language |
status |
type |
usertype |
printfmt |
prec |
scale |
iscomputed |
isoutparamisnullable collation tdscollation |
| ID |
ID 注释 |
517576882 |
1 |
4 |
MS_Description |
ID 注释 |
________ |
test1 |
517576882 |
U |
1 |
27 |
1610615063 |
96 |
0 |
0 |
2009-9-29 16:07 |
0 |
96 |
0 |
U |
1 |
8307 |
0 |
2009-9-29 16:07 |
0 |
0 |
0 |
0 |
0 |
16904 |
0 |
________ |
ID |
517576882 |
56 |
1 |
56 |
4 |
10 |
0 |
1 |
4 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
null |
2 |
|
0 |
0 |
56 |
7 |
|
10 |
0 |
0 |
00 null |