# 關于 REPLACE INTO 語句 REPLACE INTO 語句會判斷行記錄是否存在（根據主鍵索引或唯一索引判斷）。如果不存在，則插入記錄；**如果存在，則刪除已有記錄，并插入新行記錄**。目標表建議有主鍵或者唯一索引，否則容易插入重復的記錄。 示例如下： ~~~ obclient> CREATE TABLE t_replace( id number NOT NULL PRIMARY KEY , name varchar(10) NOT NULL , value number ,gmt_create timestamp NOT NULL DEFAULT current_timestamp ); Query OK, 0 rows affected (0.06 sec) obclient> REPLACE INTO t_replace values(1,'CN',2001, current_timestamp ()); Query OK, 1 row affected (0.00 sec) obclient> REPLACE INTO t_replace SELECT id,name,value,gmt_create FROM t_insert; Query OK, 5 rows affected (0.00 sec) Records: 4 Duplicates: 1 Warnings: 0 obclient> REPLACE INTO t_replace(id, name, value) values(6,'DE',20006); Query OK, 1 row affected (0.01 sec) obclient> select * from t_replace; +----+------+-------+---------------------+ | id | name | value | gmt_create | +----+------+-------+---------------------+ | 1 | CN | 10002 | 2020-04-03 18:05:45 | | 2 | US | 10103 | 2020-04-03 18:05:54 | | 3 | UK | 10003 | 2020-04-03 18:05:54 | | 4 | JP | 10005 | 2020-04-03 18:06:08 | | 6 | DE | 20006 | 2020-04-03 18:09:19 | +----+------+-------+---------------------+ 5 rows in set (0.01 sec) ~~~