如何使用PHP pdo在mysql中使用外键约束从数据库中删除数据 [英] How can I delete data from database with foreign key constraint in mysql using PHP pdo
问题描述
我在数据库中有三个表。
表1
项目
PK ProjectID
表2
学生
PK RegNo FK ProjectID表3
进度FK RegNo
现在,当我从项目中删除记录时我想要执行删除操作它应该从学生中删除,因为学生主键也作为外键进度表出现,所以它也应该从进度表中删除RegNo 。我如何才能以最佳方式实现这一目标。在此先感谢。
我尝试过:
I have three Tables in database.
table 1
projects
PK ProjectID
table 2
students
PK RegNo FK ProjectID table 3
progress FK RegNo
Now the thing i want to perform a delete operation when i delete record from project it should be deleted from students, as students primary key is also present as foreign key progress table, so it should also delete RegNo from progress table. How i can achieve this as the best possible way. Thanks in advance.
What I have tried:
$query = "
DELETE students, progress from students inner join progress on progress.RegNo=students.RegNo where students.ProjectID='$id';
DELETE FROM projects where projects.ProjectID='$id';
";
//$conn->exec($query);
$stmt = $conn->prepare($query); $stmt->execute();
它给出了外键约束违反
it gives foreign key constraint violation
推荐答案
query =
删除学生,从学生进步内部联接进度进展.RegNo = students.RegNo其中students.ProjectID ='
query = " DELETE students, progress from students inner join progress on progress.RegNo=students.RegNo where students.ProjectID='
id';
DELETE FROM项目,其中projects.ProjectID ='
id'; DELETE FROM projects where projects.ProjectID='
id';
;
//
id'; "; //
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