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
文章参考：https://www.cnblogs.com/ParanoiaApe/p/9005266.html