cleanup(prepare_stmt.go): unnecessary map delete (#5849)

gorm.go

@@ -179,7 +179,7 @@ func Open(dialector Dialector, opts ...Option) (db *DB, err error) {
 
 	preparedStmt := &PreparedStmtDB{
 		ConnPool:    db.ConnPool,
-		Stmts:       map[string](*Stmt){},
+		Stmts:       make(map[string]*Stmt),
 		Mux:         &sync.RWMutex{},
 		PreparedSQL: make([]string, 0, 100),
 	}

prepare_stmt.go

@@ -47,13 +47,12 @@ func (db *PreparedStmtDB) Close() {
 func (db *PreparedStmtDB) Reset() {
 	db.Mux.Lock()
 	defer db.Mux.Unlock()
-	for query, stmt := range db.Stmts {
-		delete(db.Stmts, query)
+
+	for _, stmt := range db.Stmts {
 		go stmt.Close()
 	}
-
 	db.PreparedSQL = make([]string, 0, 100)
-	db.Stmts = map[string](*Stmt){}
+	db.Stmts = make(map[string]*Stmt)
 }
 
 func (db *PreparedStmtDB) prepare(ctx context.Context, conn ConnPool, isTransaction bool, query string) (Stmt, error) {
@@ -93,7 +92,7 @@ func (db *PreparedStmtDB) prepare(ctx context.Context, conn ConnPool, isTransact
 
 	// Reason why cannot lock conn.PrepareContext
 	// suppose the maxopen is 1, g1 is creating record and g2 is querying record.
-	// 1. g1 begin tx, g1 is requeued because of waiting for the system call, now `db.ConnPool` db.numOpen == 1.
+	// 1. g1 begin tx, g1 is requeue because of waiting for the system call, now `db.ConnPool` db.numOpen == 1.
 	// 2. g2 select lock `conn.PrepareContext(ctx, query)`, now db.numOpen == db.maxOpen , wait for release.
 	// 3. g1 tx exec insert, wait for unlock `conn.PrepareContext(ctx, query)` to finish tx and release.
 	stmt, err := conn.PrepareContext(ctx, query)