Remove workaround for foreign keys

README.md

@@ -17,7 +17,7 @@ Install dependencies with `npm install` or `yarn`.
 Copy the `config-example.json` file to `config.json`, and change the configures.
 
 ## Database
-SYZOJ 2 uses [Sequelize](http://sequelizejs.com), which supports many database systems, including MySQL and Sqlite. But SYZOJ 2 supports **only** MySQL and Sqlite.
+SYZOJ 2 uses [Sequelize](http://sequelizejs.com), which supports many database systems, including MySQL and Sqlite.
 
 By default it use the Sqlite database `syzoj.db`, you can change it in `config.json`
 

app.js

@@ -75,19 +75,6 @@ global.syzoj = {
     global.Promise = Sequelize.Promise;
     this.db.countQuery = async (sql, options) => (await this.db.query(`SELECT COUNT(*) FROM (${sql}) AS \`__tmp_table\``, options))[0][0]['COUNT(*)'];
 
-    this.db.workAroundForeignKeyChecks = async () => {
-      if (this.config.db.dialect.toLowerCase() === 'mysql') {
-        await this.db.query('SET foreign_key_checks = 0;');
-      } else if (this.config.db.dialect.toLowerCase() === 'sqlite') {
-        await this.db.query('PRAGMA foreign_keys = OFF;');
-      }
-    }
-
-    if (!['mysql', 'sqlite'].includes(this.config.db.dialect.toLowerCase())) {
-      this.log('Unsupported database: ' + this.config.db.dialect);
-      process.exit();
-    }
-
     this.loadModels();
   },
   loadModules() {

models/problem.js

@@ -428,7 +428,6 @@ class Problem extends Model {
 
   async changeID(id) {
     id = parseInt(id);
-    await db.workAroundForeignKeyChecks();
     await db.query('UPDATE `problem`         SET `id`         = ' + id                      + ' WHERE `id`         = ' + this.id);
     await db.query('UPDATE `judge_state`     SET `problem_id` = ' + id                      + ' WHERE `problem_id` = ' + this.id);
     await db.query('UPDATE `problem_tag_map` SET `problem_id` = ' + id                      + ' WHERE `problem_id` = ' + this.id);