带有所需子查询的 MySQL UPDATE

Question

对于学校，我有以下任务将数据更新到数据库中:

Give all the employees (located into the employee table) who work on a project where the employee "50" (employee code) works on as well a salary raise of 250 euro

我知道我必须在 employee 中获得 SAL 列，然后将其提高 250 欧元。我目前通过以下查询完成此操作。

UPDATE `work` AS work
INNER JOIN `employee` AS employee ON employee.`CODE` = work.`W_CODE`
SET employee.`SAL` = (employee.`SAL` + 250)
WHERE work.`P_CODE` IN  ( # .... );

P_CODE 列代表项目标识符。在 work 表中，列出了他们正在从事的当前项目的所有 employee。

为了获取代码为 50 的员工 工作的项目，我进行了以下子查询:

UPDATE `work` AS work
INNER JOIN `employee` AS employee ON employee.`CODE` = work.`W_CODE`
SET employee.`SAL` = (employee.`SAL` + 250)
WHERE work.`P_CODE` IN (SELECT work.`P_CODE` 
                        FROM `work` AS work
                        INNER JOIN `employee` AS employee ON `employee`.`CODE` = work.`W_CODE`
                        WHERE employee.`CODE` = "50");

运行此查询时，出现此错误:

Error Code: 1093. Table 'work' is specified twice, both as a target for 'UPDATE' and as a separate source for data

为了我自己的尝试，我做了一些研究，发现我不能为此使用同一张表两次。

问题

如何在子查询起作用的地方修正这个查询？可以在我第一次加入时合并吗？

Answer 1

尝试使用不同的别名，例如:w1 和 w2 for work

UPDATE `work` 
    AS w1

    INNER JOIN `employee` AS employee
        on employee.`CODE` = w1.`W_CODE`

    SET employee.`SAL` = (employee.`SAL` + 250)

    WHERE w1.`P_CODE` IN  ( select t.my_code from (
    SELECT w2.`P_CODE` as my_code 
        FROM `work` AS w2
        INNER JOIN `employee` AS employee
            ON `employee`.`CODE` = w2.`W_CODE`
        WHERE employee.`CODE` = "50"
    )  t ) ;