postgres如何不插入重複的值

用一句sql語句搞定

INSERT INTO pm (metric, objectname, c_md5, e_md5) SELECT 'oracle', 'OR' ,'4', '7' WHERE NOT EXISTS(SELECT id FROM pm WHERE metric='oracle' AND objectname='OR');

pm爲數據庫的表名
metric, objectname, c_md5, e_md5爲對應的4個字段
‘oracle’, ‘OR’ ,‘4’, '7’爲上面對應要插入的值
SELECT id FROM pm WHERE metric=‘oracle’ AND objectname='OR’爲判斷是否在數據庫裏面有這個值,通過metric和objectname作爲判斷依據.

id爲自增id

通過這個sql語句就可以做個避免插入重複的值