MySQL中查询所有数据库名和表名

1.查询所有数据库 show databases;

2.查询指定数据库中所有表名 select table_name from information_schema.tables where table_schema=database_name and table_type=base table;

3.查询指定表中的所有字段名 select column_name from information_schema.columns where table_schema=database_name and table_name=table_name;

4.查询指定表中的所有字段名和字段类型 select column_name,data_type from information_schema.columns where table_schema=database_name and table_name=table_name;

SQLServer中查询所有数据库名和表名

1.查询所有数据库 select * from sysdatabases;

2.查询当前数据库中所有表名 select * from sysobjects where xtype=U; xtype=U:表示所有用户表，xtype=S:表示所有系统表。

3.查询指定表中的所有字段名 select name from syscolumns where id=Object_Id(table_name);

4.查询指定表中的所有字段名和字段类型 select sc.name,st.name from syscolumns sc,systypes st where sc.xtype=st.xtype and sc.id in(select id from sysobjects where xtype=U and name=table_name);

5.表结构查询

1）

select * from syscolumns where id=object_id(表名)

2）

SELECT  CASE WHEN col.colorder = 1 THEN obj.name
                  ELSE 
             END AS 表名,
        col.colorder AS 序号 ,
        col.name AS 列名 ,
        ISNULL(ep.[value], ) AS 列说明 ,
        t.name AS 数据类型 ,
        col.length AS 长度 ,
        ISNULL(COLUMNPROPERTY(col.id, col.name, Scale), 0) AS 小数位数 ,
        CASE WHEN COLUMNPROPERTY(col.id, col.name, IsIdentity) = 1 THEN √
             ELSE 
        END AS 标识 ,
        CASE WHEN EXISTS ( SELECT   1
                           FROM     dbo.sysindexes si
                                    INNER JOIN dbo.sysindexkeys sik ON si.id = sik.id
                                                              AND si.indid = sik.indid
                                    INNER JOIN dbo.syscolumns sc ON sc.id = sik.id
                                                              AND sc.colid = sik.colid
                                    INNER JOIN dbo.sysobjects so ON so.name = si.name
                                                              AND so.xtype = PK
                           WHERE    sc.id = col.id
                                    AND sc.colid = col.colid ) THEN √
             ELSE 
        END AS 主键 ,
        CASE WHEN col.isnullable = 1 THEN √
             ELSE 
        END AS 允许空 ,
        ISNULL(comm.text, ) AS 默认值
FROM    dbo.syscolumns col
        LEFT  JOIN dbo.systypes t ON col.xtype = t.xusertype
        inner JOIN dbo.sysobjects obj ON col.id = obj.id
                                         AND obj.xtype = U
                                         AND obj.status >= 0
        LEFT  JOIN dbo.syscomments comm ON col.cdefault = comm.id
        LEFT  JOIN sys.extended_properties ep ON col.id = ep.major_id
                                                      AND col.colid = ep.minor_id
                                                      AND ep.name = MS_Description
        LEFT  JOIN sys.extended_properties epTwo ON obj.id = epTwo.major_id
                                                         AND epTwo.minor_id = 0
                                                         AND epTwo.name = MS_Description
WHERE   obj.name = 表名
ORDER BY col.colorder ;

Oracle中查询所有数据库名和表名

1.查询所有数据库 由于Oralce没有库名,只有表空间,所以Oracle没有提供数据库名称查询支持，只提供了表空间名称查询。 select * from v$tablespace;--查询表空间(需要一定权限)

2.查询当前数据库中所有表名 select * from user_tables;

3.查询指定表中的所有字段名 select column_name from user_tab_columns where table_name = table_name;--表名要全大写

4.查询指定表中的所有字段名和字段类型 select column_name, data_type from user_tab_columns where table_name = table_name;--表名要全大写