insert into table (a,b,c) select

本文为博主原创，转载请注明出处：

在项目中，需要统计数据，从基础表中的数据进行统计，并插入到汇总 表中，

（1）语句形式为：Insert into Table2(field1,field2,...) select value1,value2,... from Table1

或者：Insert into Table2 select  *  from Table1

注意：（1）要求目标表Table2必须存在，并且字段field,field2...也必须存在

（2）注意Table2的主键约束，如果Table2有主键而且不为空，则 field1， field2...中必须包括主键

（3）注意语法，不要加values，和插入一条数据的sql混了，不要写成:

Insert into Table2(field1,field2,...) values (select value1,value2,... from Table1)

应用实例展示：

 <insert id="addMonthStatistics" parameterType="com.statistics.model.MonthStatistics">
        INSERT INTO tbl_statistics_month(month,livePlayCount,vodPlayCount,liveFlow,vodFlow,storeSpace,storeResidueSpace)
        SELECT DATE_FORMAT(#{month}, '%Y%m') AS 'month', SUM(t.livePlayCount) AS 'livePlayCount', SUM(t.vodPlayCount) AS 'vodPlayCount', SUM(t.liveFlow) AS 'liveFlow', SUM(t.vodFlow) AS 'vodFlow'
            , SUM(t.storeSpace) AS 'storeSpace', SUM(t.storeResidueSpace) AS 'storeResidueSpace'
        FROM (
            SELECT CASE u.playerType WHEN '' THEN u.num ELSE  END AS 'livePlayCount', CASE u.playerType WHEN '' THEN u.num ELSE  END AS 'vodPlayCount', CASE u.playerType WHEN '' THEN u.flowNum ELSE  END AS 'liveFlow', CASE u.playerType WHEN '' THEN u.flowNum ELSE  END AS 'vodFlow',  AS 'storeSpace'
                ,  AS 'storeResidueSpace'
            FROM (
                SELECT playerType, COUNT(*) AS num, ifnull(SUM(bytesSend),) AS 'flowNum'
                FROM tbl_player_statistics
                WHERE playerTime BETWEEN CONCAT(DATE_FORMAT(#{month},'%Y-%m'),'-01 00:00:00') AND CONCAT(DATE_FORMAT(last_day(#{month}),'%Y-%m-%d'),' 23:59:59')
                GROUP BY playerType
            ) u
            UNION ALL
            SELECT  AS 'livePlayCount',  AS 'vodPlayCount',  AS 'liveFlow',  AS 'vodFlow', ifnull(SUM(fileSize),) AS 'storeSpace'
                ,  - ifnull(SUM(fileSize),) AS 'storeResidueSpace'
            FROM tbl_person_space
        ) t
    </insert>