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rqxiao
V2EX  ›  MySQL

mysql 表关联 sum 的问题

  •  
  •   rqxiao · Oct 15, 2019 · 5049 views
    This topic created in 2398 days ago, the information mentioned may be changed or developed.
    SELECT
    sc.*,
    sum( scdr.coal_weight * scdr.unit_price ) totalSpending,
    sum( scrr.recharge_amount ) totalRecharge
    FROM
    self_contract sc,
    self_contract_delivery_record scdr,
    self_contract_recharge_record scrr
    WHERE
    sc.id = scdr.self_contract_id
    AND sc.id = scrr.self_contract_id
    AND sc.id = '080c8d912301f027a03214b89d9e4a0c'

    这样 sum( scrr.recharge_amount )和 sum( scdr.coal_weight * scdr.unit_price )统计错误

    会根据 self_contract_delivery_record 这张表匹配到了多少条记录 两个 sum 就都会 乘以几

    请教应该如何写 (最好是 leftjoin 的这种,self_contract 主表无论匹不匹配到都要先展示)
    4 replies    2019-10-30 17:09:27 +08:00
    taogen
        1
    taogen  
       Oct 15, 2019 via Android   ❤️ 1
    盲猜

    1. 添加 group by sc.id

    2. 修改 sum( scdr.coal_weight * scdr.unit_price ) → sum( scdr.coal_weight ) * sum (scdr.unit_price)
    superwhite
        2
    superwhite  
       Oct 25, 2019   ❤️ 1
    刚刚也遇到了这个问题,在 sum 的里面加 distinct 即可,如 sum(distinct score)
    rqxiao
        3
    rqxiao  
    OP
       Oct 30, 2019
    额 今天又碰到了 distinct 解决了
    rqxiao
        4
    rqxiao  
    OP
       Oct 30, 2019
    @superwhite 额 今天又碰到了 distinct 解决了
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