SQLite "On delete CASCADE" not cascading in Qt

Question

I have a database in Qt. it has four tables: maingroup, subgroup, parts, and position.this is my database:

CREATE TABLE `maingroup` (
    `groupName`TEXT NOT NULL UNIQUE,
     PRIMARY KEY(`groupName`)
);
CREATE TABLE `subgroup` (
    `sub`   TEXT NOT NULL UNIQUE,
    `main`  TEXT NOT NULL,
    PRIMARY KEY(`sub`),
    FOREIGN KEY(`main`) REFERENCES `maingroup`(`groupName`) ON DELETE CASCADE
);
CREATE TABLE `parts` (
    `ID`    INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
    `Part_Number`   TEXT,
    `Type`  TEXT NOT NULL,
    `Value` TEXT,
    `Voltage`   TEXT,
    `Quantity`  TEXT,
    `Position`  TEXT,
    `Picture`   TEXT,
    FOREIGN KEY(`Position`) REFERENCES `Position`(`Poistion`) ON DELETE CASCADE,
    FOREIGN KEY(`Type`) REFERENCES `subgroup`(`sub`) ON DELETE CASCADE
);

Type in table parts is foreign key refers to column sub from table subgroup. main in table subgroup is foreign key refers to column groupname in table maingroup. my problem is when I try (delete from maingroup WHERE groupName= 'dd';) in DB Browser it deletes both parent and children. But in QT this command(myQuery.exec("delete from maingroup WHERE groupName= 'dd'");) just deletes the parent field in maingroup table and not the child in subgroup and part table and the main column in subgroup table refers to a field in maingroup table that does not exist. what is wrong here?what should i do?

Answer 1

You need to turn on the foreign-key pragma by executing another statement before your DELETE statement.

QSqlQuery q;
q.exec("PRAGMA foreign_keys = ON");
q.exec("DELETE FROM ...");

This was able to cascade deletes, and should also be sufficient to solve other foreign-key related issues.

Credits to this forum.qt.io post.