fix: new mysql db client

Author: 710leo

dskit/mysql/mysql.go

@@ -115,14 +115,14 @@ func (m *MySQL) NewConn(ctx context.Context, database string) (*gorm.DB, error)
 	}()
 
 	dsn := fmt.Sprintf("%s:%s@tcp(%s)/%s?charset=utf8&parseTime=True", shard.User, shard.Password, shard.Addr, database)
-
-	return sqlbase.NewDB(
+	db, err = sqlbase.NewDB(
 		ctx,
 		mysql.Open(dsn),
 		shard.MaxIdleConns,
 		shard.MaxOpenConns,
 		time.Duration(shard.ConnMaxLifetime)*time.Second,
 	)
+	return db, err
 }
 
 func (m *MySQL) ShowDatabases(ctx context.Context) ([]string, error) {