DB2、Oracle、SqlServer、Mysql下查看外鍵以及外鍵關聯的表和表字段

DB2、Oracle、SqlServer、Mysql四種數據庫中，查看錶的外鍵信息，以及外鍵關聯的表及表字段的語句。
輸出的格式一樣，所以之截圖了一個， 有多個外鍵會返回所有的外鍵值。

Oralce ：

select c.table_name,c.constraint_name,d.column_name,cl.table_name,cl.column_name
  from user_cons_columns cl
  left join user_constraints c on cl.constraint_name = c.r_constraint_name left join user_cons_columns d on d.constraint_name=c.constraint_name
  where c.constraint_type = 'R' and c.owner='ROOT' and c.table_name = 'STUDENT4'

sqlServer:

SELECT object_name(b.fkeyid),a.name,(SELECT name FROM syscolumns WHERE colid = b.fkey AND id = b.fkeyid),object_name(b.rkeyid),(SELECT name FROM syscolumns WHERE colid = b.rkey AND id = b.rkeyid)
FROM sysobjects a
JOIN sysforeignkeys b ON a.id = b.constid
JOIN sysobjects c ON a.parent_obj = c.id
WHERE a.xtype = 'F' AND c.xtype = 'U' and c.name='grade'

Mysql:

select table_name,constraint_name,column_name,referenced_table_name,referenced_column_name
from INFORMATION_SCHEMA.KEY_COLUMN_USAGE
where table_schema='testdemo' and table_name='grade' and referenced_table_name is not null and referenced_column_name is not null;

DB2:

select tabname,constname,fk_colnames,reftabname,pk_colnames from syscat.references  where owner='DB2INST1' and tabname='GRADE'

所有的輸出都一樣， 我設置成了： 表名，索引名，表的字段名，引用表的名，引用表的字段名。