Add method UpdateColumn, DropColumn, AddIndex, RemoveIndex. Will document it to README when get a better implementation to fix known issues

chain.go

@@ -215,21 +215,6 @@ func (s *Chain) Or(querystring interface{}, args ...interface{}) *Chain {
 	return s
 }
 
-func (s *Chain) CreateTable(value interface{}) *Chain {
-	s.do(value).createTable()
-	return s
-}
-
-func (s *Chain) DropTable(value interface{}) *Chain {
-	s.do(value).dropTable()
-	return s
-}
-
-func (s *Chain) AutoMigrate(value interface{}) *Chain {
-	s.do(value).autoMigrate()
-	return s
-}
-
 func (s *Chain) Unscoped() *Chain {
 	s.unscoped = true
 	return s
@@ -281,6 +266,41 @@ func (s *Chain) Rollback() *Chain {
 	return s
 }
 
+func (s *Chain) CreateTable(value interface{}) *Chain {
+	s.do(value).createTable()
+	return s
+}
+
+func (s *Chain) DropTable(value interface{}) *Chain {
+	s.do(value).dropTable()
+	return s
+}
+
+func (s *Chain) AutoMigrate(value interface{}) *Chain {
+	s.do(value).autoMigrate()
+	return s
+}
+
+func (s *Chain) UpdateColumn(column string, typ string) *Chain {
+	s.do(s.value).updateColumn(column, typ)
+	return s
+}
+
+func (s *Chain) DropColumn(column string) *Chain {
+	s.do(s.value).dropColumn(column)
+	return s
+}
+
+func (s *Chain) AddIndex(column string, index_name ...string) *Chain {
+	s.do(s.value).addIndex(column, index_name...)
+	return s
+}
+
+func (s *Chain) RemoveIndex(column string) *Chain {
+	s.do(s.value).removeIndex(column)
+	return s
+}
+
 func (s *Chain) validSql(str string) (result bool) {
 	result = regexp.MustCompile("^\\s*[\\w\\s,.*()]*\\s*$").MatchString(str)
 	if !result {

do.go

@@ -649,25 +649,45 @@ func (s *Do) createTable() *Do {
 		}
 	}
 
-	s.sql = fmt.Sprintf(
+	s.sql = fmt.Sprintf("CREATE TABLE %v (%v)", s.tableName(), strings.Join(sqls, ","))
-		"CREATE TABLE %v (%v)",
-		s.tableName(),
-		strings.Join(sqls, ","),
-	)
 
 	s.exec()
 	return s
 }
 
 func (s *Do) dropTable() *Do {
-	s.sql = fmt.Sprintf(
+	s.sql = fmt.Sprintf("DROP TABLE %v", s.tableName())
-		"DROP TABLE %v",
-		s.tableName(),
-	)
 	s.exec()
 	return s
 }
 
+func (s *Do) updateColumn(column string, typ string) {
+	s.sql = fmt.Sprintf("ALTER TABLE %v MODIFY %v %v", s.tableName(), column, typ)
+	s.exec()
+}
+
+func (s *Do) dropColumn(column string) {
+	s.sql = fmt.Sprintf("ALTER TABLE %v DROP COLUMN %v", s.tableName(), column)
+	s.exec()
+}
+
+func (s *Do) addIndex(column string, names ...string) {
+	var index_name string
+	if len(names) > 0 {
+		index_name = names[0]
+	} else {
+		index_name = fmt.Sprintf("index_%v_on_%v", s.tableName(), column)
+	}
+
+	s.sql = fmt.Sprintf("CREATE INDEX %v ON %v(%v);", index_name, s.tableName(), column)
+	s.exec()
+}
+
+func (s *Do) removeIndex(index_name string) {
+	s.sql = fmt.Sprintf("DROP INDEX %v ON %v", index_name, s.tableName())
+	s.exec()
+}
+
 func (s *Do) autoMigrate() *Do {
 	var table_name string
 	sql := fmt.Sprintf("SELECT table_name FROM INFORMATION_SCHEMA.tables where table_name = %v", s.addToVars(s.tableName()))