Oracle之mergeInto

ORACLE  实现存在时 - 更新，不存在时，插入

MERGE INTO table B 
USING (SELECT COUNT(*) AS QUNATUM FROM table C WHERE C.CROSSID = '20000031100804'AND C.LANEID = '' AND C.NEXTCROSSID = '') T 
ON (T.QUNATUM > 0) 
WHEN MATCHED THEN UPDATE SET B.SBBH = '',B.LANEID = '120',B.NEXTCROSSID = '20000031100805'
WHEN NOT MATCHED THEN INSERT (B.SBBH, B.LANEID, B.NEXTCROSSID,B.CROSSID) VALUES ('','5','20000031100806','20000031100810') ;

对应的Mybatis:

<update id="mergeIntoLianeroadmapping" parameterType="java.lang.String">
        MERGE INTO table B
        USING (SELECT COUNT(C.CROSSID) AS QUNATUM FROM table C WHERE C.CROSSID = #{crossId}
        AND C.LANEID = #{laneId} AND C.NEXTCROSSID = #{nextCrossId}) T
        ON (T.QUNATUM > 0)
        WHEN MATCHED THEN
           UPDATE SET B.SBBH = '',B.LANEID = '6',B.NEXTCROSSID = #{nextCrossId}
        WHEN NOT MATCHED THEN
            INSERT (B.SBBH, B.LANEID, B.NEXTCROSSID,B.CROSSID) VALUES ('',#{laneId},#{nextCrossId},#{crossId})
</update>

merge语法是根据源表对目标表进行匹配查询，匹配成功时更新，不成功时插入。

其基本语法规则是

merge into 目标表 a

using 源表 b

on(a.条件字段1=b.条件字段1 and a.条件字段2=b.条件字段2 ……)  

when matched then update set a.更新字段=b.字段

when  not macthed then insert into a(字段1,字段2……)values(值1,值2……)