几种常见数据库查询判断表和字段是否存在sql

1、MSSQL Server

 表： select  COUNT (*)  from  dbo.sysobjects WHERE name =  'table_name' ；
 字段： select  COUNT (*)  from syscolumns WHERE id=object_id(‘table_name’)  and name =  'column_name' ；
2、My SQL

 表： select COUNT (*) from information_schema.tables WHERE table_name = 'table_name' ；
 字段： select COUNT (*) from information_schema.columns WHERE table_name = 'table_name' and column_name = 'column_name' ；
3、Oracle

 表： SELECT count (*) FROM USER_OBJECTS WHERE  OBJECT_NAME =  'table_name' ；
 字段： SELECT COUNT (*) FROM USER_TAB_COLUMNS WHERE TABLE_NAME = 'table_name' and column_name = 'column_name' ；
4、PostgreSql

 表： select count (*) from information_schema.tables WHERE table_schema= 'table_schema' and  table_name = 'table_name' ；
 字段： select count (*) from information_schema.columns WHERE table_schema= 'table_schema' and table_name = 'table_name' and  column_name= 'column_name' ；

注意，表名和字段名都要大写，oracle已经测过，其他请自测