insert into table (a,b,c) select

Posted 2020-10-22 香吧香

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       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 ‘1‘ THEN u.num ELSE 0 END AS ‘livePlayCount‘, CASE u.playerType WHEN ‘2‘ THEN u.num ELSE 0 END AS ‘vodPlayCount‘, CASE u.playerType WHEN ‘1‘ THEN u.flowNum ELSE 0 END AS ‘liveFlow‘, CASE u.playerType WHEN ‘2‘ THEN u.flowNum ELSE 0 END AS ‘vodFlow‘, 0 AS ‘storeSpace‘
                , 0 AS ‘storeResidueSpace‘
            FROM (
                SELECT playerType, COUNT(*) AS num, ifnull(SUM(bytesSend),0) 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 0 AS ‘livePlayCount‘, 0 AS ‘vodPlayCount‘, 0 AS ‘liveFlow‘, 0 AS ‘vodFlow‘, ifnull(SUM(fileSize),0) AS ‘storeSpace‘
                , 8192000 - ifnull(SUM(fileSize),0) AS ‘storeResidueSpace‘
            FROM tbl_person_space
        ) t
    </insert>