From cb5b9f6f9e6cda72f090d1c69a21e0363cade02b Mon Sep 17 00:00:00 2001
From: Ariel Mashraki <7413593+a8m@users.noreply.github.com>
Date: Thu, 23 Jan 2020 20:25:48 +0200
Subject: [PATCH] dialect/sql: add drop/add-index for older version of mysql
 (#315)

Add support for MySQL 5.6.35
---
 dialect/sql/builder.go      | 22 ++++++++++++++++++++++
 dialect/sql/builder_test.go |  7 +++++++
 2 files changed, 29 insertions(+)

diff --git a/dialect/sql/builder.go b/dialect/sql/builder.go
index 44b526049..1f4fc5983 100644
--- a/dialect/sql/builder.go
+++ b/dialect/sql/builder.go
@@ -265,6 +265,28 @@ func (t *TableAlter) RenameIndex(curr, new string) *TableAlter {
 	return t
 }
 
+// DropIndex appends the `DROP INDEX` clause to the given `ALTER TABLE` statement.
+func (t *TableAlter) DropIndex(name string) *TableAlter {
+	t.Queries = append(t.Queries, Raw(fmt.Sprintf("DROP INDEX %s", t.Quote(name))))
+	return t
+}
+
+// AddIndex appends the `ADD INDEX` clause to the given `ALTER TABLE` statement.
+func (t *TableAlter) AddIndex(idx *IndexBuilder) *TableAlter {
+	b := &Builder{dialect: t.dialect}
+	b.WriteString("ADD ")
+	if idx.unique {
+		b.WriteString("UNIQUE ")
+	}
+	b.WriteString("INDEX ")
+	b.Ident(idx.name)
+	b.Nested(func(b *Builder) {
+		b.IdentComma(idx.columns...)
+	})
+	t.Queries = append(t.Queries, b)
+	return t
+}
+
 // AddForeignKey adds a foreign key constraint to the `ALTER TABLE` statement.
 func (t *TableAlter) AddForeignKey(fk *ForeignKeyBuilder) *TableAlter {
 	t.Queries = append(t.Queries, &Wrapper{"ADD CONSTRAINT %s", fk})
diff --git a/dialect/sql/builder_test.go b/dialect/sql/builder_test.go
index 5440305c1..e9e40efca 100644
--- a/dialect/sql/builder_test.go
+++ b/dialect/sql/builder_test.go
@@ -200,6 +200,13 @@ func TestBuilder(t *testing.T) {
 			input:     AlterTable("users").RenameIndex("old", "new"),
 			wantQuery: "ALTER TABLE `users` RENAME INDEX `old` TO `new`",
 		},
+		{
+			input: AlterTable("users").
+				DropIndex("old").
+				AddIndex(CreateIndex("new1").Columns("c1", "c2")).
+				AddIndex(CreateIndex("new2").Columns("c1", "c2").Unique()),
+			wantQuery: "ALTER TABLE `users` DROP INDEX `old`, ADD INDEX `new1`(`c1`, `c2`), ADD UNIQUE INDEX `new2`(`c1`, `c2`)",
+		},
 		{
 			input: Dialect(dialect.Postgres).AlterIndex("old").
 				Rename("new"),