Not able to add references columns or foreign keys about sqlite HOT 6 CLOSED

ALTER TABLE child ADD CONSTRAINT fk_child_parent
                  FOREIGN KEY (parent_id) 
                  REFERENCES parent(id);

CREATE TABLE child ( 
    id           INTEGER PRIMARY KEY, 
    parent_id    INTEGER, 
    description  TEXT,
    FOREIGN KEY (parent_id) REFERENCES parent(id)
);

INSERT INTO child (id,description) SELECT id,description FROM your_table;

        // create tables
        let sqlcmd: string = `
        PRAGMA foreign_keys = ON;
        CREATE TABLE IF NOT EXISTS users (
            id INTEGER PRIMARY KEY NOT NULL,
            email TEXT UNIQUE NOT NULL,
            name TEXT,
            company TEXT,
            size FLOAT,
            age INTEGER
        );
        CREATE TABLE IF NOT EXISTS messages (
            id INTEGER PRIMARY KEY NOT NULL,
            userid INTEGER,
            title TEXT NOT NULL,
            body TEXT NOT NULL,
            FOREIGN KEY (userid) REFERENCES users(id)
        );
        CREATE INDEX users_index_name ON users (name);
        `;
        result = await this._SQLiteService.execute(sqlcmd);
        console.log('1 result.changes')
        if(result.changes.changes === 0 || result.changes.changes === 1) {
          sqlcmd = `
          BEGIN TRANSACTION;
          INSERT INTO users (name,email,age) VALUES ("Simpson","[email protected]",69);
          INSERT INTO users (name,email,age) VALUES ("Jones","[email protected]",42);
          INSERT INTO messages (id,userid,title,body) VALUES (1,1,"Message 1","Blabla");
          INSERT INTO messages (id,userid,title,body) VALUES (2,1,"Message 2","More Blabla");
          INSERT INTO messages (id,userid,title,body) VALUES (3,2,"Message 1","Response from Blabla");          
          COMMIT TRANSACTION;
          `;         
          result = await this._SQLiteService.execute(sqlcmd);
          console.log('2 result.changes')
          if(result.changes.changes === 5) {
          }
       }