Return value of forech statement in mybatis

As follows, I wrote a query to update multiple rows using the foreach statement.

<update id="deleteVhcleInfos" parameterType="java.util.List"><foreach collection="list" item="item" index="index" separator=";" open="DECLARE BEGIN" close="; END;">        UPDATE TB_VHCL_MANAGE<set><if test='item.vhclno != null and item.vhclno != ""'>                , DEL_YN = 'Y'</if><if test='item.mdfcUserno != null and item.mdfcUserno != ""'>                , MDFC_USERNO = ${item.mdfcUserno}                , MDFC_DTTM = SYSDATE</if>            </set><where><if test='item.vhclno != null and item.vhclno != ""'>                AND VHCLNO = #{item.vhclno}</if></where></foreach></update>

I knew that in this case, the execution result of the first query (1 for success and 0 for failure) is returned. But for my query, -1 was returned even though the query was executed successfully. Why is this happening?

I have now written the code to return a failure message if the return value is less than 1.If returning -1 is a normal behavior, how should I handle it?