mysql和oracle查询出的一条结果中的多个字段拼接

1,mysql

concat('a','b','c')和concat_ws('a','b','c')的区别:前者如果有某个值为空,结果为空;后者如果有某个值为空,可以忽略这个控制

SELECT
    concat_ws('',FORE_TWO,THIRD_POSITION,FOURTH_POSITION,FIFTH_POSITION) AS code
    FROM
      TABLE_A
    WHERE
      ID= #{id}

2,oracle

SELECT
    FORE_TWO||THIRD_POSITION||FOURTH_POSITION||FIFTH_POSITION AS code
    FROM
      TABLE_A
    WHERE
      ID = #{id}