Support revert old column attributes

README.md

@@ -237,6 +237,8 @@ CREATE TABLE user (
 	//CREATE UNIQUE INDEX `idx_name_age` ON `user`(`name`, `age`);
 
 	println(sql1.StringDown())
+	//ALTER TABLE `user` MODIFY COLUMN `id` int(11);
+	//ALTER TABLE `user` MODIFY COLUMN `updated_at` datetime;
 	//DROP INDEX `idx_name_age` ON `user`;
 }
 ```

README_zh.md

@@ -232,11 +232,13 @@ CREATE TABLE user (
 
 	sql1.Diff(*sql2)
 	println(sql1.StringUp())
-	// ALTER TABLE `user` MODIFY COLUMN `id` int(11) AUTO_INCREMENT PRIMARY KEY;
-	// ALTER TABLE `user` MODIFY COLUMN `updated_at` datetime DEFAULT CURRENT_TIMESTAMP() ON UPDATE CURRENT_TIMESTAMP();
-	// CREATE UNIQUE INDEX `idx_name_age` ON `user`(`name`, `age`);
+	//ALTER TABLE `user` MODIFY COLUMN `id` int(11) AUTO_INCREMENT PRIMARY KEY;
+	//ALTER TABLE `user` MODIFY COLUMN `updated_at` datetime DEFAULT CURRENT_TIMESTAMP() ON UPDATE CURRENT_TIMESTAMP();
+	//CREATE UNIQUE INDEX `idx_name_age` ON `user`(`name`, `age`);
 
 	println(sql1.StringDown())
-	// DROP INDEX `idx_name_age` ON `user`;
+	//ALTER TABLE `user` MODIFY COLUMN `id` int(11);
+	//ALTER TABLE `user` MODIFY COLUMN `updated_at` datetime;
+	//DROP INDEX `idx_name_age` ON `user`;
 }
 ```

avro/builder.go

@@ -59,19 +59,19 @@ func getAvroType(col element.Column) interface{} {
 			"type":            "string",
 			"connect.version": 1,
 			"connect.parameters": map[string]string{
-				"allowed": strings.Join(col.MysqlType.Elems, ","),
+				"allowed": strings.Join(col.CurrentAttr.MysqlType.Elems, ","),
 			},
 			"connect.default": "init",
 			"connect.name":    "io.debezium.data.Enum",
 		}
 	}
 
-	switch col.MysqlType.EvalType() {
+	switch col.CurrentAttr.MysqlType.EvalType() {
 	case types.ETInt:
 		return "int"
 
 	case types.ETDecimal:
-		displayFlen, displayDecimal := col.MysqlType.Flen, col.MysqlType.Decimal
+		displayFlen, displayDecimal := col.CurrentAttr.MysqlType.Flen, col.CurrentAttr.MysqlType.Decimal
 		return map[string]interface{}{
 			"type":            "bytes",
 			"scale":           displayDecimal,

element/column.go

@@ -22,28 +22,34 @@ const (
 	LowerRestoreFlag = format.RestoreStringSingleQuotes | format.RestoreKeyWordLowercase | format.RestoreNameLowercase | format.RestoreNameBackQuotes
 )
 
-// Column ...
-type Column struct {
-	Node
+type SqlAttr struct {
 	MysqlType *types.FieldType
 	PgType    *ptypes.T
 	LiteType  *sqlite.Type
 	Options   []*ast.ColumnOption
 	Comment   string
 }
 
+// Column ...
+type Column struct {
+	Node
+
+	CurrentAttr  SqlAttr
+	PreviousAttr SqlAttr
+}
+
 // GetType ...
 func (c Column) GetType() byte {
-	if c.MysqlType != nil {
-		return c.MysqlType.Tp
+	if c.CurrentAttr.MysqlType != nil {
+		return c.CurrentAttr.MysqlType.Tp
 	}
 
 	return 0
 }
 
 // HasDefaultValue ...
 func (c Column) HasDefaultValue() bool {
-	for _, opt := range c.Options {
+	for _, opt := range c.CurrentAttr.Options {
 		if opt.Tp == ast.ColumnOptionDefaultValue {
 			return true
 		}
@@ -54,7 +60,7 @@ func (c Column) HasDefaultValue() bool {
 
 func (c Column) hashValue() string {
 	strHash := sql.EscapeSqlName(c.Name)
-	strHash += c.typeDefinition()
+	strHash += c.typeDefinition(false)
 	hash := md5.Sum([]byte(strHash))
 	return hex.EncodeToString(hash[:])
 }
@@ -71,7 +77,7 @@ func (c Column) migrationUp(tbName, after string, ident int) []string {
 			strSql += strings.Repeat(" ", ident-len(c.Name))
 		}
 
-		strSql += c.definition()
+		strSql += c.definition(false)
 
 		if ident < 0 {
 			if after != "" {
@@ -90,10 +96,27 @@ func (c Column) migrationUp(tbName, after string, ident int) []string {
 		return []string{fmt.Sprintf(sql.AlterTableDropColumnStm(), sql.EscapeSqlName(tbName), sql.EscapeSqlName(c.Name))}
 
 	case MigrateModifyAction:
-		def := strings.Replace(c.definition(), sql.PrimaryOption(), "", 1)
+		def, isPk := c.pkDefinition(false)
+		if isPk {
+			if _, isPrevPk := c.pkDefinition(true); isPrevPk {
+				// avoid repeat define primary key
+				def = strings.Replace(def, " "+sql.PrimaryOption(), "", 1)
+			}
+		}
 
 		return []string{fmt.Sprintf(sql.AlterTableModifyColumnStm(), sql.EscapeSqlName(tbName), sql.EscapeSqlName(c.Name)+def)}
 
+	case MigrateRevertAction:
+		prevDef, isPrevPk := c.pkDefinition(true)
+		if isPrevPk {
+			if _, isPk := c.pkDefinition(false); isPk {
+				// avoid repeat define primary key
+				prevDef = strings.Replace(prevDef, " "+sql.PrimaryOption(), "", 1)
+			}
+		}
+
+		return []string{fmt.Sprintf(sql.AlterTableModifyColumnStm(), sql.EscapeSqlName(tbName), sql.EscapeSqlName(c.Name)+prevDef)}
+
 	case MigrateRenameAction:
 		return []string{fmt.Sprintf(sql.AlterTableRenameColumnStm(), sql.EscapeSqlName(tbName), sql.EscapeSqlName(c.OldName), sql.EscapeSqlName(c.Name))}
 
@@ -103,12 +126,12 @@ func (c Column) migrationUp(tbName, after string, ident int) []string {
 }
 
 func (c Column) migrationCommentUp(tbName string) []string {
-	if c.Comment == "" || sql.GetDialect() != sql_templates.PostgresDialect {
+	if c.CurrentAttr.Comment == "" || sql.GetDialect() != sql_templates.PostgresDialect {
 		return nil
 	}
 
 	// apply for postgres only
-	return []string{fmt.Sprintf(sql.ColumnComment(), tbName, c.Name, c.Comment)}
+	return []string{fmt.Sprintf(sql.ColumnComment(), tbName, c.Name, c.CurrentAttr.Comment)}
 }
 
 func (c Column) migrationDown(tbName, after string) []string {
@@ -123,7 +146,7 @@ func (c Column) migrationDown(tbName, after string) []string {
 		c.Action = MigrateAddAction
 
 	case MigrateModifyAction:
-		return nil
+		c.Action = MigrateRevertAction
 
 	case MigrateRenameAction:
 		c.Name, c.OldName = c.OldName, c.Name
@@ -135,10 +158,19 @@ func (c Column) migrationDown(tbName, after string) []string {
 	return c.migrationUp(tbName, after, -1)
 }
 
-func (c Column) definition() string {
-	strSql := c.typeDefinition()
+func (c Column) pkDefinition(isPrev bool) (string, bool) {
+	attr := c.CurrentAttr
+	if isPrev {
+		attr = c.PreviousAttr
+	}
+	strSql := c.typeDefinition(isPrev)
+
+	isPrimaryKey := false
+	for _, opt := range attr.Options {
+		if opt.Tp == ast.ColumnOptionPrimaryKey {
+			isPrimaryKey = true
+		}
 
-	for _, opt := range c.Options {
 		b := bytes.NewBufferString("")
 		var ctx *format.RestoreCtx
 
@@ -157,17 +189,27 @@ func (c Column) definition() string {
 		strSql += " " + b.String()
 	}
 
-	return strSql
+	return strSql, isPrimaryKey
+}
+
+func (c Column) definition(isPrev bool) string {
+	def, _ := c.pkDefinition(isPrev)
+	return def
 }
 
-func (c Column) typeDefinition() string {
+func (c Column) typeDefinition(isPrev bool) string {
+	attr := c.CurrentAttr
+	if isPrev {
+		attr = c.PreviousAttr
+	}
+
 	switch {
-	case sql.IsPostgres() && c.PgType != nil:
-		return " " + c.PgType.SQLString()
-	case sql.IsSqlite() && c.LiteType != nil:
-		return " " + c.LiteType.Name.Name
-	case c.MysqlType != nil:
-		return " " + c.MysqlType.String()
+	case sql.IsPostgres() && attr.PgType != nil:
+		return " " + attr.PgType.SQLString()
+	case sql.IsSqlite() && attr.LiteType != nil:
+		return " " + attr.LiteType.Name.Name
+	case attr.MysqlType != nil:
+		return " " + attr.MysqlType.String()
 	}
 
 	return "" // column type is empty

element/migration.go

@@ -150,7 +150,7 @@ func (m *Migration) AddComment(tbName, colName, comment string) {
 		return
 	}
 
-	m.Tables[id].Columns[colIdx].Comment = comment
+	m.Tables[id].Columns[colIdx].CurrentAttr.Comment = comment
 }
 
 // AddIndex ...

element/node.go

@@ -12,6 +12,8 @@ const (
 	MigrateRemoveAction
 	// MigrateModifyAction ...
 	MigrateModifyAction
+	// MigrateRevertAction ...
+	MigrateRevertAction
 	// MigrateRenameAction ...
 	MigrateRenameAction
 )

element/table.go

@@ -62,18 +62,18 @@ func (t *Table) AddColumn(col Column) {
 		t.Columns[id] = col
 
 	default:
-		t.Columns[id].Options = append(t.Columns[id].Options, col.Options...)
+		t.Columns[id].CurrentAttr.Options = append(t.Columns[id].CurrentAttr.Options, col.CurrentAttr.Options...)
 
-		if size := len(t.Columns[id].Options); size > 0 {
-			for i := range t.Columns[id].Options[:size-1] {
-				if t.Columns[id].Options[i].Tp == ast.ColumnOptionPrimaryKey {
-					t.Columns[id].Options[i], t.Columns[id].Options[size-1] = t.Columns[id].Options[size-1], t.Columns[id].Options[i]
+		if size := len(t.Columns[id].CurrentAttr.Options); size > 0 {
+			for i := range t.Columns[id].CurrentAttr.Options[:size-1] {
+				if t.Columns[id].CurrentAttr.Options[i].Tp == ast.ColumnOptionPrimaryKey {
+					t.Columns[id].CurrentAttr.Options[i], t.Columns[id].CurrentAttr.Options[size-1] = t.Columns[id].CurrentAttr.Options[size-1], t.Columns[id].CurrentAttr.Options[i]
 					break
 				}
 			}
 		}
 
-		t.Columns[id].MysqlType = col.MysqlType
+		t.Columns[id].CurrentAttr.MysqlType = col.CurrentAttr.MysqlType
 		return
 	}
 
@@ -291,10 +291,11 @@ func (t *Table) Diff(old Table) {
 	for i := range t.Columns {
 		if j := old.getIndexColumn(t.Columns[i].Name); t.Columns[i].Action == MigrateAddAction &&
 			j >= 0 && old.Columns[j].Action != MigrateNoAction {
-			if hasChangedMysqlOptions(t.Columns[i].Options, old.Columns[j].Options) ||
-				hasChangedMysqlType(t.Columns[i].MysqlType, old.Columns[j].MysqlType) ||
-				hasChangePostgresType(t.Columns[i].PgType, old.Columns[j].PgType) {
+			if hasChangedMysqlOptions(t.Columns[i].CurrentAttr.Options, old.Columns[j].CurrentAttr.Options) ||
+				hasChangedMysqlType(t.Columns[i].CurrentAttr.MysqlType, old.Columns[j].CurrentAttr.MysqlType) ||
+				hasChangePostgresType(t.Columns[i].CurrentAttr.PgType, old.Columns[j].CurrentAttr.PgType) {
 				t.Columns[i].Action = MigrateModifyAction
+				t.Columns[i].PreviousAttr = old.Columns[j].CurrentAttr
 			} else {
 				t.Columns[i].Action = MigrateNoAction
 			}

sql-parser/mysql.go

@@ -73,11 +73,13 @@ func (p *Parser) Enter(in ast.Node) (ast.Node, bool) {
 						})
 					} else {
 						p.Migration.AddColumn(alter.Table.Text(), element.Column{
-							Node:      element.Node{Name: cols[0], Action: element.MigrateAddAction},
-							MysqlType: nil,
-							Options: []*ast.ColumnOption{
-								{
-									Tp: ast.ColumnOptionPrimaryKey,
+							Node: element.Node{Name: cols[0], Action: element.MigrateAddAction},
+							CurrentAttr: element.SqlAttr{
+								MysqlType: nil,
+								Options: []*ast.ColumnOption{
+									{
+										Tp: ast.ColumnOptionPrimaryKey,
+									},
 								},
 							},
 						})
@@ -113,9 +115,11 @@ func (p *Parser) Enter(in ast.Node) (ast.Node, bool) {
 				if len(alter.Specs[i].NewColumns) > 0 {
 					for j := range alter.Specs[i].NewColumns {
 						col := element.Column{
-							Node:      element.Node{Name: alter.Specs[i].NewColumns[j].Name.Name.O, Action: element.MigrateModifyAction},
-							MysqlType: alter.Specs[i].NewColumns[j].Tp,
-							Comment:   alter.Specs[i].Comment,
+							Node: element.Node{Name: alter.Specs[i].NewColumns[j].Name.Name.O, Action: element.MigrateModifyAction},
+							CurrentAttr: element.SqlAttr{
+								MysqlType: alter.Specs[i].NewColumns[j].Tp,
+								Comment:   alter.Specs[i].Comment,
+							},
 						}
 						p.Migration.AddColumn(alter.Table.Name.O, col)
 					}
@@ -161,11 +165,13 @@ func (p *Parser) Enter(in ast.Node) (ast.Node, bool) {
 					})
 				} else {
 					tb.AddColumn(element.Column{
-						Node:      element.Node{Name: cols[0], Action: element.MigrateAddAction},
-						MysqlType: nil,
-						Options: []*ast.ColumnOption{
-							{
-								Tp: ast.ColumnOptionPrimaryKey,
+						Node: element.Node{Name: cols[0], Action: element.MigrateAddAction},
+						CurrentAttr: element.SqlAttr{
+							MysqlType: nil,
+							Options: []*ast.ColumnOption{
+								{
+									Tp: ast.ColumnOptionPrimaryKey,
+								},
 							},
 						},
 					})
@@ -218,10 +224,12 @@ func (p *Parser) Enter(in ast.Node) (ast.Node, bool) {
 		}
 
 		column := element.Column{
-			Node:      element.Node{Name: def.Name.Name.O, Action: element.MigrateAddAction},
-			MysqlType: def.Tp,
-			Options:   def.Options,
-			Comment:   comment,
+			Node: element.Node{Name: def.Name.Name.O, Action: element.MigrateAddAction},
+			CurrentAttr: element.SqlAttr{
+				MysqlType: def.Tp,
+				Options:   def.Options,
+				Comment:   comment,
+			},
 		}
 		p.Migration.AddColumn("", column)
 	}

sql-parser/postgresql.go

@@ -92,20 +92,24 @@ func (p *Parser) walker(ctx interface{}, node interface{}) (stop bool) {
 
 		case *tree.AlterTableAlterColumnType:
 			col := element.Column{
-				Node:   element.Node{Name: nc.Column.String(), Action: element.MigrateModifyAction},
-				PgType: nc.ToType,
+				Node: element.Node{Name: nc.Column.String(), Action: element.MigrateModifyAction},
+				CurrentAttr: element.SqlAttr{
+					PgType: nc.ToType,
+				},
 			}
 			p.Migration.AddColumn(n.Table.String(), col)
 
 		case *tree.AlterTableSetDefault:
 			if nc.Default != nil {
 				col := element.Column{
 					Node: element.Node{Name: nc.Column.String(), Action: element.MigrateModifyAction},
-					Options: []*ast.ColumnOption{{
-						Expr:     nil,
-						Tp:       ast.ColumnOptionDefaultValue,
-						StrValue: nc.Default.String(),
-					}},
+					CurrentAttr: element.SqlAttr{
+						Options: []*ast.ColumnOption{{
+							Expr:     nil,
+							Tp:       ast.ColumnOptionDefaultValue,
+							StrValue: nc.Default.String(),
+						}},
+					},
 				}
 				p.Migration.AddColumn(n.Table.String(), col)
 			}
@@ -166,9 +170,11 @@ func postgresColumn(n *tree.ColumnTableDef) (element.Column, []element.Index) {
 	}
 
 	return element.Column{
-		Node:    element.Node{Name: n.Name.String(), Action: element.MigrateAddAction},
-		PgType:  n.Type,
-		Options: opts,
+		Node: element.Node{Name: n.Name.String(), Action: element.MigrateAddAction},
+		CurrentAttr: element.SqlAttr{
+			PgType:  n.Type,
+			Options: opts,
+		},
 	}, indexes
 }