fix(connection-manager): add switch for dynamic import (#12014)

lib/dialects/abstract/connection-manager.js

@@ -71,8 +71,15 @@ class ConnectionManager {
       if (this.sequelize.config.dialectModule) {
       if (this.sequelize.config.dialectModule) {
         return this.sequelize.config.dialectModule;
         return this.sequelize.config.dialectModule;
       }
       }
-      return require(moduleName);
-
+      // This is needed so that bundlers (like webpack) know which library to include in the bundle
+      switch (moduleName) {
+        case 'pg': return require('pg');
+        case 'mysql2': return require('mysql2');
+        case 'mariadb': return require('mariadb');
+        case 'sqlite3': return require('sqlite3');
+        case 'tedious': return require('tedious');
+        default: return require(moduleName);
+      }
     } catch (err) {
     } catch (err) {
       if (err.code === 'MODULE_NOT_FOUND') {
       if (err.code === 'MODULE_NOT_FOUND') {
         if (this.sequelize.config.dialectModulePath) {
         if (this.sequelize.config.dialectModulePath) {