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  • mysql操作语句总结

            项目中经常用到sql语句进行数据增删查改操作,下面总结了一下:

    比如 查找指定客户最近订单

    根据id查询按日期降序排序取第一条。(降序排序取第一条)

    SELECT * FROM t_customer_order WHERE cusId=#{cusId} ORDER BY orderdate DESC LIMIT 0,1;

     查询存在一个表而不在另一个表中的数据记录

    select A.ID from A where A.ID not in (select ID from B)

    查询某个字段为null的记录

    SELECT LastName,FirstName,Address FROM Persons WHERE Address IS NULL

    SELECT
      excute.i_id as id,
      excute.i_plan_drill_id as drillId,
      excute.i_status as status,
      info.c_name as planName,
      excute.c_alarm_source_name as alarmSourceName,
      excute.c_alarm_event_name as alarmEventname,
      excute.c_alarm_area as alarmArea,
      excute.c_creator as creator,
      excute.d_create_time as createTime
    FROM
      plan_excute excute,
      plan_info info
    WHERE
      excute.i_plan_id = info.i_id
    AND
      excute.i_plan_drill_id is null
    ORDER BY

        excute.d_create_time desc

      查询客户订单总金额(牵涉到多表关联查询)

    这里牵涉到三个表,t_customer (客户表),t_customer_order(客户订单表),t_order_details(客户订单详情表),需用到左连接查询和分组查询

    select  t1.name,SUM(t3.sum) as gx  from t_customer  t1 left join t_customer_order t2 on t1.id = t2.cusId left join t_order_details t3 on t2.id= t3.orderId group by t1.id

    1、先左连接查询出所有关联记录

    2、再根据字段分组查询所有记录

    3、最后查询只关心的字段记录

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  • 原文地址:https://www.cnblogs.com/jedjia/p/mysql-CRUD.html
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