added Select method for special select column express

engine.go

@@ -510,6 +510,12 @@ func (engine *Engine) Distinct(columns ...string) *Session {
 	return session.Distinct(columns...)
 }
 
+func (engine *Engine) Select(str string) *Session {
+	session := engine.NewSession()
+	session.IsAutoClose = true
+	return session.Select(str)
+}
+
 // only use the paramters as select or update columns
 func (engine *Engine) Cols(columns ...string) *Session {
 	session := engine.NewSession()

session.go

@@ -172,6 +172,12 @@ func (session *Session) SetExpr(column string, expression string) *Session {
 	return session
 }
 
+// Method Cols provides some columns to special
+func (session *Session) Select(str string) *Session {
+	session.Statement.Select(str)
+	return session
+}
+
 // Method Cols provides some columns to special
 func (session *Session) Cols(columns ...string) *Session {
 	session.Statement.Cols(columns...)
@@ -621,12 +627,20 @@ func (statement *Statement) convertIdSql(sqlStr string) string {
 	return ""
 }
 
-func (session *Session) cacheGet(bean interface{}, sqlStr string, args ...interface{}) (has bool, err error) {
+func (session *Session) canCache() bool {
-	// if has no reftable, then don't use cache currently
 	if session.Statement.RefTable == nil ||
 		session.Statement.JoinStr != "" ||
 		session.Statement.RawSQL != "" ||
-		session.Tx != nil {
+		session.Tx != nil || 
+		len(session.Statement.selectStr) > 0 {
+		return false
+	}
+	return true
+}
+
+func (session *Session) cacheGet(bean interface{}, sqlStr string, args ...interface{}) (has bool, err error) {
+	// if has no reftable, then don't use cache currently
+	if !session.canCache() {
 		return false, ErrCacheFailed
 	}
 
@@ -724,10 +738,9 @@ func (session *Session) cacheGet(bean interface{}, sqlStr string, args ...interf
 }
 
 func (session *Session) cacheFind(t reflect.Type, sqlStr string, rowsSlicePtr interface{}, args ...interface{}) (err error) {
-	if session.Statement.RefTable == nil ||
+	if !session.canCache() || 
 		indexNoCase(sqlStr, "having") != -1 ||
-		indexNoCase(sqlStr, "group by") != -1 ||
+		indexNoCase(sqlStr, "group by") != -1 {
-		session.Tx != nil {
 		return ErrCacheFailed
 	}
 
@@ -1183,6 +1196,9 @@ func (session *Session) Find(rowsSlicePtr interface{}, condiBean ...interface{})
 	var args []interface{}
 	if session.Statement.RawSQL == "" {
 		var columnStr string = session.Statement.ColumnStr
+		if len(session.Statement.selectStr) > 0 {
+			columnStr = session.Statement.selectStr
+		} else {
 			if session.Statement.JoinStr == "" {
 				if columnStr == "" {
 					if session.Statement.GroupByStr != "" {
@@ -1200,6 +1216,7 @@ func (session *Session) Find(rowsSlicePtr interface{}, condiBean ...interface{})
 					}
 				}
 			}
+		}
 
 		session.Statement.attachInSql()
 

statement.go

@@ -49,6 +49,7 @@ type Statement struct {
 	GroupByStr    string
 	HavingStr     string
 	ColumnStr     string
+	selectStr string
 	columnMap     map[string]bool
 	useAllCols    bool
 	OmitStr       string
@@ -100,6 +101,7 @@ func (statement *Statement) Init() {
 	statement.UseAutoTime = true
 	statement.IsDistinct = false
 	statement.TableAlias = ""
+	statement.selectStr = ""
 	statement.allUseBool = false
 	statement.useAllCols = false
 	statement.mustColumnMap = make(map[string]bool)
@@ -862,6 +864,12 @@ func (statement *Statement) Distinct(columns ...string) *Statement {
 	return statement
 }
 
+// replace select
+func (s *Statement) Select(str string) *Statement {
+	s.selectStr = str
+	return s
+}
+
 // Generate "col1, col2" statement
 func (statement *Statement) Cols(columns ...string) *Statement {
 	newColumns := col2NewCols(columns...)
@@ -1146,6 +1154,9 @@ func (statement *Statement) genGetSql(bean interface{}) (string, []interface{})
 	statement.BeanArgs = args
 
 	var columnStr string = statement.ColumnStr
+	if len(statement.selectStr) > 0 {
+		columnStr = statement.selectStr
+	} else {
 		if len(statement.JoinStr) == 0 {
 			if len(columnStr) == 0 {
 				if statement.GroupByStr != "" {
@@ -1163,6 +1174,7 @@ func (statement *Statement) genGetSql(bean interface{}) (string, []interface{})
 				}
 			}
 		}
+	}
 
 	statement.attachInSql() // !admpub!  fix bug:Iterate func missing "... IN (...)"
 	return statement.genSelectSql(columnStr), append(statement.Params, statement.BeanArgs...)

xorm.go

@@ -17,7 +17,7 @@ import (
 )
 
 const (
-	Version string = "0.4.3.0520"
+	Version string = "0.4.3.0524"
 )
 
 func regDrvsNDialects() bool {