Fix statement modifier support

chainable_api.go

@@ -27,6 +27,8 @@ func (db *DB) Clauses(conds ...clause.Expression) (tx *DB) {
 	for _, cond := range conds {
 		if c, ok := cond.(clause.Interface); ok {
 			tx.Statement.AddClause(c)
+		} else if optimizer, ok := cond.(StatementModifier); ok {
+			optimizer.ModifyStatement(tx.Statement)
 		} else {
 			whereConds = append(whereConds, cond)
 		}

clause/clause.go

@@ -48,7 +48,7 @@ func (c Clause) Build(builder Builder) {
 		}
 
 		if c.AfterNameExpression != nil {
-			c.BeforeExpression.Build(builder)
+			c.AfterNameExpression.Build(builder)
 			builder.WriteByte(' ')
 		}
 

statement.go

@@ -202,12 +202,11 @@ func (stmt *Statement) AddClause(v clause.Interface) {
 	if optimizer, ok := v.(StatementModifier); ok {
 		optimizer.ModifyStatement(stmt)
 	} else {
-		c, ok := stmt.Clauses[v.Name()]
-		if !ok {
-			c.Name = v.Name()
-		}
+		name := v.Name()
+		c, _ := stmt.Clauses[name]
+		c.Name = name
 		v.MergeClause(&c)
-		stmt.Clauses[v.Name()] = c
+		stmt.Clauses[name] = c
 	}
 }