sql/mssql: initial diff and migrate

sql/mssql/convert.go

@@ -145,7 +145,7 @@ type columnDesc struct {
 }
 
 // ParseType returns the schema.Type value represented by the given raw type.
-// The raw value is expected to follow the format in PostgreSQL information schema
+// The raw value is expected to follow the format in MS-SQL information schema
 // or as an input for the CREATE TABLE statement.
 func ParseType(typ string) (schema.Type, error) {
 	d, err := parseColumn(typ)

sql/mssql/diff.go

@@ -0,0 +1,67 @@
+// Copyright 2021-present The Atlas Authors. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
+package mssql
+
+import (
+	"ariga.io/atlas/sql/internal/sqlx"
+	"ariga.io/atlas/sql/schema"
+)
+
+// DefaultDiff provides basic diffing capabilities for MS-SQL dialects.
+// Note, it is recommended to call Open, create a new Driver and use its Differ
+// when a database connection is available.
+var DefaultDiff schema.Differ = &sqlx.Diff{DiffDriver: &diff{}}
+
+// A diff provides a MS-SQL implementation for sqlx.DiffDriver.
+type diff struct{ conn }
+
+// SchemaAttrDiff returns a changeset for migrating schema attributes from one state to the other.
+func (d *diff) SchemaAttrDiff(_, _ *schema.Schema) []schema.Change {
+	// No special schema attribute diffing for MS-SQL.
+	return nil
+}
+
+// TableAttrDiff returns a changeset for migrating table attributes from one state to the other.
+func (d *diff) TableAttrDiff(_, _ *schema.Table) ([]schema.Change, error) {
+	// Not implemented yet.
+	return nil, nil
+}
+
+// ColumnChange returns the schema changes (if any) for migrating one column to the other.
+func (d *diff) ColumnChange(_ *schema.Table, _, _ *schema.Column) (schema.ChangeKind, error) {
+	// Not implemented yet.
+	return schema.NoChange, nil
+}
+
+// IsGeneratedIndexName reports if the index name was generated by the database.
+func (d *diff) IsGeneratedIndexName(_ *schema.Table, _ *schema.Index) bool {
+	// Not implemented yet.
+	return false
+}
+
+// IndexAttrChanged reports if the index attributes were changed.
+// The default type is BTREE if no type was specified.
+func (*diff) IndexAttrChanged(_, _ []schema.Attr) bool {
+	// Not implemented yet.
+	return false
+}
+
+// IndexPartAttrChanged reports if the index-part attributes were changed.
+func (*diff) IndexPartAttrChanged(_, _ *schema.Index, _ int) bool {
+	// Not implemented yet.
+	return false
+}
+
+// ReferenceChanged reports if the foreign key referential action was changed.
+func (*diff) ReferenceChanged(_, _ schema.ReferenceOption) bool {
+	// Not implemented yet.
+	return false
+}
+
+// AnnotateChanges implements the sqlx.ChangeAnnotator interface.
+func (*diff) AnnotateChanges(_ []schema.Change, _ *schema.DiffOptions) error {
+	// Not implemented yet.
+	return nil
+}

sql/mssql/driver.go

@@ -54,8 +54,10 @@ func Open(db schema.ExecQuerier) (migrate.Driver, error) {
 		return nil, fmt.Errorf("mssql: scan server property: %w", err)
 	}
 	return &Driver{
-		conn:      c,
-		Inspector: &inspect{c},
+		conn:        c,
+		Differ:      &sqlx.Diff{DiffDriver: &diff{c}},
+		Inspector:   &inspect{c},
+		PlanApplier: &planApply{c},
 	}, nil
 }
 

sql/mssql/migrate.go

@@ -0,0 +1,34 @@
+// Copyright 2021-present The Atlas Authors. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
+package mssql
+
+import (
+	"context"
+
+	"ariga.io/atlas/sql/internal/sqlx"
+	"ariga.io/atlas/sql/migrate"
+	"ariga.io/atlas/sql/schema"
+)
+
+// DefaultPlan provides basic planning capabilities for MS-SQL dialects.
+// Note, it is recommended to call Open, create a new Driver and use its
+// migrate.PlanApplier when a database connection is available.
+var DefaultPlan migrate.PlanApplier = &planApply{conn: conn{ExecQuerier: sqlx.NoRows}}
+
+// A planApply provides migration capabilities for schema elements.
+type planApply struct{ conn }
+
+// ApplyChanges applies the changes on the database. An error is returned
+// if the driver is unable to produce a plan to do so, or one of the statements
+// is failed or unsupported.
+func (p *planApply) ApplyChanges(ctx context.Context, changes []schema.Change, opts ...migrate.PlanOption) error {
+	return sqlx.ApplyChanges(ctx, changes, p, opts...)
+}
+
+// PlanChanges returns a migration plan for the given schema changes.
+func (p *planApply) PlanChanges(_ context.Context, _ string, _ []schema.Change, _ ...migrate.PlanOption) (*migrate.Plan, error) {
+	// Not implemented yet.
+	return nil, nil
+}