一、oracle
1、获取当前oracle数据库中的所有表
select table_name from user_tables
2、查询某个表中的字段名称、类型、精度、长度、是否为空
- select COLUMN_NAME,DATA_TYPE,DATA_PRECISION,DATA_SCALE,NULLABLE
- from user_tab_columns
- where table_name ='YourTableName'
3、查询某个表中的主键字段名
- select col.column_name
- from user_constraints con, user_cons_columns col
- where con.constraint_name = col.constraint_name
- and con.constraint_type='P'
- and col.table_name = 'YourTableName'
4、查询某个表中的外键字段名称、所引用表名、所应用字段名
- select distinct(col.column_name),r.table_name,r.column_name
- from
- user_constraints con,
- user_cons_columns col,
- (select t2.table_name,t2.column_name,t1.r_constraint_name
- from user_constraints t1,user_cons_columns t2
- where t1.r_constraint_name=t2.constraint_name
- and t1.table_name='YourTableName'
- ) r
- where con.constraint_name=col.constraint_name
- and con.r_constraint_name=r.r_constraint_name
- and con.table_name='YourTableName'
5、如何从Oracle中取得表的注释
user_tab_comments;表注释
user_col_comments;表字段注释
以上两个只能获取自己用户的表的注释信息，如果要访问自己
能够访问的其他用户的表，则需要使用：
all_tab_comments;表注释
all_col_comments;表字段注释
当然，如果有DBA权限，则可以使用
dba_tab_comments;表注释
dba_col_comments;表字段注释
dba*和all*最好指定owner条件。user*没有该字段
user_tab_comments;表注释
user_col_comments;表字段注释
二、SQLServer
1、读取库中的所有表名
select name from sysobjects where xtype='u'
2、字段
- SELECT c.name,t.name,c.xprec,c.xscale,c.isnullable
- FROM systypes t,syscolumns c
- WHERE t.xtype=c.xtype
- AND c.id = (SELECT id FROM sysobjects WHERE name='YourTableName')
- ORDER BY c.colid
3、主键（参考SqlServer系统存储过程sp_pkeys）
- select COLUMN_NAME = convert(sysname,c.name)
- from
- sysindexes i, syscolumns c, sysobjects o
- where o.id = object_id('[YourTableName]')
- and o.id = c.id
- and o.id = i.id
- and (i.status & 0x800) = 0x800
- and (c.name = index_col ('[YourTableName]', i.indid, 1) or
- c.name = index_col ('[YourTableName]', i.indid, 2) or
- c.name = index_col ('[YourTableName]', i.indid, 3) or
- c.name = index_col ('[YourTableName]', i.indid, 4) or
- c.name = index_col ('[YourTableName]', i.indid, 5) or
- c.name = index_col ('[YourTableName]', i.indid, 6) or
- c.name = index_col ('[YourTableName]', i.indid, 7) or
- c.name = index_col ('[YourTableName]', i.indid, 8) or
- c.name = index_col ('[YourTableName]', i.indid, 9) or
- c.name = index_col ('[YourTableName]', i.indid, 10) or
- c.name = index_col ('[YourTableName]', i.indid, 11) or
- c.name = index_col ('[YourTableName]', i.indid, 12) or
- c.name = index_col ('[YourTableName]', i.indid, 13) or
- c.name = index_col ('[YourTableName]', i.indid, 14) or
- c.name = index_col ('[YourTableName]', i.indid, 15) or
- c.name = index_col ('[YourTableName]', i.indid, 16)
- )
4、外键
- select t1.name,t2.rtableName,t2.name
- from
- (select col.name, f.constid as temp
- from syscolumns col,sysforeignkeys f
- where f.fkeyid=col.id
- and f.fkey=col.colid
- and f.constid in
- ( select distinct(id)
- from sysobjects
- where OBJECT_NAME(parent_obj)='YourTableName'
- and xtype='F'
- )
- ) as t1 ,
- (select OBJECT_NAME(f.rkeyid) as rtableName,col.name, f.constid as temp
- from syscolumns col,sysforeignkeys f
- where f.rkeyid=col.id
- and f.rkey=col.colid
- and f.constid in
- ( select distinct(id)
- from sysobjects
- where OBJECT_NAME(parent_obj)='YourTableName'
- and xtype='F'
- )
- ) as t2
- where t1.temp=t2.temp
三、Access
1、所有表清单
- conn.Open();
dt= conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });
2、表结构
conn.Open();
dtColumnsInfo = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Columns, new object[] { null, null, strTableName,null });
