on duplicate key update 的意思是插入的数据中存在与唯一主键相同的即存在则更新，不存在则插入，适用于mysql数据库，oracle数据库中使用

MERGE INTO ..... using ...on ...when matched then ... when not matched then
实例如下：

mysql:

insert into table (PID,SPWID,BTCD,SV,BXCD,BSW,BW,DSW,SC,NT,MODITIME)
VALUES
<foreach collection="list" item="bt" index="index" separator=",">
    ( #{bt.pid},#{bt.spwid},#{bt.btcd},#{bt.sv},#{bt.bxcd},#{bt.bsw},#{bt.bw},#{bt.dsw},#{bt.sc},#{bt.nt},#{bt.moditime} )
</foreach>
ON DUPLICATE KEY UPDATE
    pid = values(pid),
    spwid = values(spwid),
    btcd = values(btcd),
    sv = values(sv),
    bxcd = values(bxcd),
    bsw = values(bsw),
    bw = values(bw),
    dsw = values(dsw),
    sc = values(sc),
    nt = values(nt),
    moditime = values(moditime)

对应oracle：

MERGE INTO table t2
USING(
<foreach collection="list" item="bt" index="index" separator="union all">
    SELECT
    #{bt.pid,jdbcType=VARCHAR} PID,
    #{bt.spwid,jdbcType=VARCHAR} SPWID,
    #{bt.btcd,jdbcType=VARCHAR} BTCD,
    #{bt.sv,jdbcType=DOUBLE} SV,
    #{bt.bxcd,jdbcType=VARCHAR} BXCD,
    #{bt.bsw,jdbcType=DOUBLE} BSW,
    #{bt.bw,jdbcType=DOUBLE} BW,
    #{bt.dsw,jdbcType=DOUBLE} DSW,
    #{bt.sc,jdbcType=DOUBLE} SC,
    #{bt.nt,jdbcType=VARCHAR} NT,
    #{bt.moditime,jdbcType=DATE} MODITIME
    from DUAL
</foreach>
)t1
ON (t2.PID = t1.PID)
WHEN MATCHED THEN
UPDATE SET
t2.SPWID=t1.SPWID,
t2.BTCD=t1.BTCD,
t2.SV=t1.SV,
t2.BXCD=t1.BXCD,
t2.BSW=t1.BSW,
t2.BW=t1.BW,
t2.DSW=t1.DSW,
t2.SC=t1.SC,
t2.NT=t1.NT,
t2.MODITIME=t1.MODITIME
WHEN NOT MATCHED THEN
INSERT (PID,SPWID,BTCD,SV,BXCD,BSW,BW,DSW,SC,NT,MODITIME) VALUES
(t1.PID,t1.SPWID,t1.BTCD,t1.SV,t1.BXCD,t1.BSW,t1.BW,t1.DSW,t1.SC,t1.NT,t1.MODITIME)