Apply every RENAME COLUMN in a multi-column MySQL ALTER

internal/endtoend/testdata/ddl_alter_table_rename_column_multiple/mysql/query.sql

@@ -0,0 +1,2 @@
+/* name: GetFoo :many */
+SELECT qux, quux FROM foo;

internal/endtoend/testdata/ddl_alter_table_rename_column_multiple/mysql/schema.sql

@@ -0,0 +1,4 @@
+CREATE TABLE foo (bar text, baz text);
+ALTER TABLE foo
+ RENAME COLUMN bar TO qux,
+ RENAME COLUMN baz TO quux;

internal/endtoend/testdata/ddl_alter_table_rename_column_multiple/mysql/sqlc.json

@@ -0,0 +1,12 @@
+{
+ "version": "1",
+ "packages": [
+ {
+ "path": "go",
+ "engine": "mysql",
+ "name": "querytest",
+ "schema": "schema.sql",
+ "queries": "query.sql"
+ }
+ ]
+}

internal/engine/dolphin/convert.go

@@ -95,14 +95,13 @@ func (c *cc) convertAlterTableStmt(n *pcast.AlterTableStmt) ast.Node {
  // spew.Dump("add const", spec)
 
  case pcast.AlterTableRenameColumn:
- // TODO: Returning here may be incorrect if there are multiple specs
  oldName := spec.OldColumnName.String()
  newName := spec.NewColumnName.String()
-return &ast.RenameColumnStmt{
-Table: parseTableName(n.Table),
-Col: &ast.ColumnRef{Name: oldName},
-NewName: &newName,
- }
+alt.Cmds.Items = append(alt.Cmds.Items, &ast.AlterTableCmd{
+Name:  &oldName,
+Newname: &newName,
+Subtype: ast.AT_RenameColumn,
+ })
 
  case pcast.AlterTableRenameTable:
  // TODO: Returning here may be incorrect if there are multiple specs

internal/sql/ast/alter_table_cmd.go

@@ -8,6 +8,7 @@ const (
 	AT_DropColumn
 	AT_DropNotNull
 	AT_SetNotNull
+	AT_RenameColumn
 )
 
 type AlterTableType int
@@ -24,6 +25,8 @@ func (t AlterTableType) String() string {
  return "DropNotNull"
 	case AT_SetNotNull:
  return "SetNotNull"
+	case AT_RenameColumn:
+ return "RenameColumn"
 	default:
  return "Unknown"
 	}
@@ -32,6 +35,7 @@ func (t AlterTableType) String() string {
 type AlterTableCmd struct {
 	Subtype AlterTableType
 	Name *string
+	Newname *string
 	Def *ColumnDef
 	Newowner *RoleSpec
 	Behavior DropBehavior

internal/sql/catalog/table.go

@@ -177,6 +177,8 @@ func isStmtImplemented(stmt *ast.AlterTableStmt) bool {
  implemented = true
  case ast.AT_SetNotNull:
  implemented = true
+ case ast.AT_RenameColumn:
+ implemented = true
  }
  }
 	}
@@ -215,6 +217,10 @@ func (c *Catalog) alterTable(stmt *ast.AlterTableStmt) error {
  if err := table.setNotNull(cmd); err != nil {
  return err
  }
+ case ast.AT_RenameColumn:
+ if err := c.renameColumnOnTable(table, *cmd.Name, *cmd.Newname); err != nil {
+ return err
+ }
  }
  }
 	}
@@ -394,22 +400,26 @@ func (c *Catalog) renameColumn(stmt *ast.RenameColumnStmt) error {
 	if err != nil {
  return checkMissing(err, stmt.MissingOk)
 	}
+	return c.renameColumnOnTable(tbl, stmt.Col.Name, *stmt.NewName)
+}
+
+func (c *Catalog) renameColumnOnTable(tbl *Table, oldName, newName string) error {
 	idx := -1
 	for i := range tbl.Columns {
- if tbl.Columns[i].Name == stmt.Col.Name {
+ if tbl.Columns[i].Name == oldName {
  idx = i
  }
- if tbl.Columns[i].Name == *stmt.NewName {
- return sqlerr.ColumnExists(tbl.Rel.Name, *stmt.NewName)
+ if tbl.Columns[i].Name == newName {
+ return sqlerr.ColumnExists(tbl.Rel.Name, newName)
  }
 	}
 	if idx == -1 {
- return sqlerr.ColumnNotFound(tbl.Rel.Name, stmt.Col.Name)
+ return sqlerr.ColumnNotFound(tbl.Rel.Name, oldName)
 	}
-	tbl.Columns[idx].Name = *stmt.NewName
+	tbl.Columns[idx].Name = newName
 
 	if tbl.Columns[idx].linkedType {
- name := fmt.Sprintf("%s_%s", tbl.Rel.Name, *stmt.NewName)
+ name := fmt.Sprintf("%s_%s", tbl.Rel.Name, newName)
  rename := &ast.RenameTypeStmt{
  Type: &tbl.Columns[idx].Type,
  NewName: &name,