Question

我的项目是学校的停车系统。为了获得总收入，我将总结许可价格列：

select sum(permit.price) from permit;

然后，为了获得总违规收入，我将获得每种违规类型的票价（1），然后乘以违规类型的数量（2,3和4）

select sum(violation_type.amount_due) from violation_type where violation_type_id = 1;

select count(Violation_Type_ID = '1') from violation where violation_type_id = '1';

select count(Violation_Type_ID = '2') from violation where violation_type_id = '2';

select count(Violation_Type_ID = '3') from violation where violation_type_id = '3';

select count(Violation_Type_ID = '4') from violation where violation_type_id = '4';

如何将所有这些放在1个查询中？感谢。

Answer 1

SELECT
    SUM(CASE
        WHEN vt.violation_type_id = '1' THEN 1
        ELSE 0
    END) ViolationType1Count,
    SUM(CASE
        WHEN vt.violation_type_id = '1' THEN vt.amount_due
        ELSE 0.0
    END) ViolationType1AmtDue,
    SUM(CASE
        WHEN vt.violation_type_id = '2' THEN 1
        ELSE 0
    END) ViolationType2Count,
    SUM(CASE
        WHEN vt.violation_type_id = '2' THEN vt.amount_due
        ELSE 0.0
    END) ViolationType2AmtDue,
    etc.
FROM
    violation_type vt INNER JOIN
        violation v
    ON vt.violation_type_id = v.violation_type_id

Answer 2

如果你想在SQL中总结一切，那么：

SELECT SUM(TotalAmount) AS TotalAmount
FROM (
      SELECT SUM(permit.price) AS TotalAmount 
      FROM permit

      UNION ALL

      SELECT SUM(vt.amount_due)
      FROM violation v
      JOIN violation_type vt
      ON v.violation_type_id = vt.violation_type_id

    ) as Sums

如果您需要按违规类型细分，那么它将是：

          SELECT v.violation_type,
          COUNT() [Count], 
          SUM(vt.amount_due) TotalAmount
          FROM violation v
          JOIN violation_type vt
          ON v.violation_type_id = vt.violation_type_id
          GROUP ON v.violation_type

如果一个vio_type_id是一个varchar而不是一个数字，那么你会加入如下：

     ON CAST(v.violation_type_id AS INT) = vt.violation_type_id

我可以在SQL中组合查询吗？我想获得一个总收入数字。这是我的查询

2 个答案: