Question

我正在使用SQLite，并且正在尝试将旧行从学生表移到Students_Old，并从Students_Import复制新行。

问题是我有多个主键：

CREATE TABLE "Students" (
`LastName`  TEXT NOT NULL,
`FirstName` TEXT NOT NULL,
`BornDate`  TEXT NOT NULL,
`Class` TEXT NOT NULL,
`Photo` TEXT,
`ValidUntil`    CHAR(10),
PRIMARY KEY(LastName,FirstName,BornDate))

所有表都具有此结构（除了缺少Photo和ValidUntil的Students_Import）。

到目前为止，我已设法用以下方法复制旧行：

INSERT INTO Students_Old 
SELECT DISTINCT a.LastName, a.FirstName, a.BornDate, a.Class, a.Photo, a.ValidUntil FROM
Students a LEFT JOIN Students_Import b ON a.LastName =b.LastName AND a.FirstName=b.FirstName AND a.BornDate=b.BornDate WHERE b.LastName is NULL;

用这个添加新行：

INSERT INTO Students 
SELECT DISTINCT a.LastName, a.FirstName, a.BornDate, a.Class, "", "" FROM 
Students_Import a LEFT JOIN Students b ON a.LastName =b.LastName AND a.FirstName=b.FirstName AND a.BornDate=b.BornDate WHERE b.LastName is NULL

但我无法弄清楚如何删除学生中的旧行（在Students_Import中不存在）。

我尝试了一些这方面的变种：

DELETE FROM Students WHERE (LastName, FirstName, BornDate) IN
(SELECT DISTINCT a.LastName, a.FirstName, a.BornDate, a.Class, a.Photo, a.ValidUntil FROM 
Students a LEFT JOIN Students_Import b ON a.LastName =b.LastName AND a.FirstName=b.FirstName AND a.BornDate=b.BornDate WHERE b.LastName is NULL);

但我只是语法错误，或者我不能在多行上使用它。

我将不胜感激任何帮助！

Answer 1

IN不适用于多列。

要查找另一个表中不存在的行，请使用带有correlated subquery的NOT EXISTS：

DELETE FROM Students
WHERE NOT EXISTS (SELECT 1
                  FROM Students_Import
                  WHERE Students_Import.LastName  = Students.LastName
                    AND Students_Import.FirstName = Students.FirstName
                    AND Students_Import.BornDate  = Students.BornDate);

Answer 2

我认为你在IN子句中可以有多个列。

怎么样： man pandoc

使用复合主键删除另一个表中不存在的行

2 个答案: