部分数据库的查询列名或表名

Mysql 查找字段
show full columns from tablename

SQL Server 查找字段
select name from syscolumns
where id=object_id('tablename')
or id=object_id('tablename2')

DB2 查找字段
SELECT COLNAME FROM SYSCAT.COLUMNS WHERE TABNAME='tablename' AND TABSCHEMA='SCHEMA'";

SQL Server 显示所有表名
select name from sysobjects where xtype='U'

Mysql 显示所有表名
show all tables