如何重写查询以在没有 WITH 语法的情况下工作

How to rewrite query to work without WITH syntax

只是寻求一些关于如何在不使用 WITH 的情况下重写此查询的帮助。 我知道我需要用子查询的主体替换对 WITH 子查询的引用,但我不确定如何。谢谢

WITH current_employees AS (
    SELECT DISTINCT emp_id
    FROM appointment
    WHERE end_date IS NULL
),
appointments_2015 AS (
    SELECT a.emp_id, salary,
        CASE WHEN start_date < '2015-01-01' THEN '2015-01-01' ELSE start_date END AS start_date,
        CASE WHEN end_date < '2016-01-01' THEN end_date ELSE '2015-12-31' END AS end_date
    FROM appointment a
        JOIN current_employees ce ON a.emp_id = ce.emp_id
    WHERE start_date < '2016-01-01' AND (end_date >= '2015-01-01' OR end_date IS NULL)
)
SELECT
    emp_id,
    SUM( salary * (end_date - start_date + 1) / 365 ) AS total
FROM appointments_2015
GROUP BY emp_id

由于 CTE 仅被引用一次,因此更改非常简单。为每个 CTE 创建一个派生的 table(有时称为“内联视图”或简称为 sub-select)

SELECT
    emp_id,
    SUM( salary * (end_date - start_date + 1) / 365 ) AS total
FROM (
  SELECT a.emp_id, salary,
      CASE WHEN start_date < '2015-01-01' THEN '2015-01-01' ELSE start_date END AS start_date,
      CASE WHEN end_date < '2016-01-01' THEN end_date ELSE '2015-12-31' END AS end_date
  FROM appointment a
      JOIN (
        SELECT DISTINCT emp_id
        FROM appointment
        WHERE end_date IS NULL
      ) current_employees ce ON a.emp_id = ce.emp_id
  WHERE start_date < '2016-01-01' AND (end_date >= '2015-01-01' OR end_date IS NULL)
) appointments_2015 
GROUP BY emp_id

你好像想要在职员工2015年的工资。如果是:

SELECT a.emp_id,
       SUM( salary * (end_date_2015 - start_date_2015 + 1) / 365 ) AS total
FROM (SELECT a.*,
             (CASE WHEN start_date < '2015-01-01' THEN '2015-01-01'
                   WHEN start_date < '2016-01-01' THEN start_date
              END) AS start_date_2015,
             (CASE WHEN end_date < '2015-01-01' THEN NULL
                   WHEN end_date < '2016-01-01' THEN end_date
                   ELSE '2015-12-31'
              END) AS end_date
      FROM appointments_2015 a
     ) a
GROUP BY emp_id
HAVING COUNT(end_date) <> COUNT(*);