Merge pull request #290 from evalphobia/feature/select-for-update

Added feature for SELECT ... FOR UPDATE

mssql_dialect.go

@@ -509,6 +509,10 @@ func (db *mssql) CreateTableSql(table *core.Table, tableName, storeEngine, chars
 	return sql
 }
 
+func (db *mssql) ForUpdateSql(query string) string {
+	return query
+}
+
 func (db *mssql) Filters() []core.Filter {
 	return []core.Filter{&core.IdFilter{}, &core.QuoteFilter{}}
 }

session.go

@@ -225,6 +225,12 @@ func (session *Session) Distinct(columns ...string) *Session {
 	return session
 }
 
+// Set Read/Write locking for UPDATE
+func (session *Session) ForUpdate() *Session {
+	session.Statement.IsForUpdate = true
+	return session
+}
+
 // Only not use the paramters as select or update columns
 func (session *Session) Omit(columns ...string) *Session {
 	session.Statement.Omit(columns...)

sqlite3_dialect.go

@@ -250,6 +250,10 @@ func (db *sqlite3) DropIndexSql(tableName string, index *core.Index) string {
 	return fmt.Sprintf("DROP INDEX %v", quote(idxName))
 }
 
+func (db *sqlite3) ForUpdateSql(query string) string {
+	return query
+}
+
 /*func (db *sqlite3) ColumnCheckSql(tableName, colName string) (string, []interface{}) {
 	args := []interface{}{tableName}
 	sql := "SELECT name FROM sqlite_master WHERE type='table' and name = ? and ((sql like '%`" + colName + "`%') or (sql like '%[" + colName + "]%'))"

statement.go

@@ -66,6 +66,7 @@ type Statement struct {
 	UseCache      bool
 	UseAutoTime   bool
 	IsDistinct    bool
+	IsForUpdate   bool
 	TableAlias    string
 	allUseBool    bool
 	checkVersion  bool
@@ -102,6 +103,7 @@ func (statement *Statement) Init() {
 	statement.UseCache = true
 	statement.UseAutoTime = true
 	statement.IsDistinct = false
+	statement.IsForUpdate = false
 	statement.TableAlias = ""
 	statement.selectStr = ""
 	statement.allUseBool = false
@@ -802,6 +804,12 @@ func (statement *Statement) Distinct(columns ...string) *Statement {
 	return statement
 }
 
+// Generate "SELECT ... FOR UPDATE" statment
+func (statement *Statement) ForUpdate() *Statement {
+	statement.IsForUpdate = true
+	return statement
+}
+
 // replace select
 func (s *Statement) Select(str string) *Statement {
 	s.selectStr = str
@@ -1184,6 +1192,7 @@ func (statement *Statement) genSelectSql(columnStr string) (a string) {
 		distinct = "DISTINCT "
 	}
 
+	var dialect core.Dialect = statement.Engine.Dialect()
 	var top string
 	var mssqlCondi string
 	/*var orderBy string
@@ -1195,7 +1204,7 @@ func (statement *Statement) genSelectSql(columnStr string) (a string) {
 	if statement.WhereStr != "" {
 		whereStr = fmt.Sprintf(" WHERE %v", statement.WhereStr)
 		if statement.ConditionStr != "" {
-			whereStr = fmt.Sprintf("%v %s %v", whereStr, statement.Engine.Dialect().AndStr(),
+			whereStr = fmt.Sprintf("%v %s %v", whereStr, dialect.AndStr(),
 				statement.ConditionStr)
 		}
 	} else if statement.ConditionStr != "" {
@@ -1203,7 +1212,7 @@ func (statement *Statement) genSelectSql(columnStr string) (a string) {
 	}
 	var fromStr string = " FROM " + statement.Engine.Quote(statement.TableName())
 	if statement.TableAlias != "" {
-		if statement.Engine.dialect.DBType() == core.ORACLE {
+		if dialect.DBType() == core.ORACLE {
 			fromStr += " " + statement.Engine.Quote(statement.TableAlias)
 		} else {
 			fromStr += " AS " + statement.Engine.Quote(statement.TableAlias)
@@ -1213,7 +1222,7 @@ func (statement *Statement) genSelectSql(columnStr string) (a string) {
 		fromStr = fmt.Sprintf("%v %v", fromStr, statement.JoinStr)
 	}
 
-	if statement.Engine.dialect.DBType() == core.MSSQL {
+	if dialect.DBType() == core.MSSQL {
 		if statement.LimitN > 0 {
 			top = fmt.Sprintf(" TOP %d ", statement.LimitN)
 		}
@@ -1263,17 +1272,20 @@ func (statement *Statement) genSelectSql(columnStr string) (a string) {
 	if statement.OrderStr != "" {
 		a = fmt.Sprintf("%v ORDER BY %v", a, statement.OrderStr)
 	}
-	if statement.Engine.dialect.DBType() != core.MSSQL && statement.Engine.dialect.DBType() != core.ORACLE {
+	if dialect.DBType() != core.MSSQL && dialect.DBType() != core.ORACLE {
 		if statement.Start > 0 {
 			a = fmt.Sprintf("%v LIMIT %v OFFSET %v", a, statement.LimitN, statement.Start)
 		} else if statement.LimitN > 0 {
 			a = fmt.Sprintf("%v LIMIT %v", a, statement.LimitN)
 		}
-	} else if statement.Engine.dialect.DBType() == core.ORACLE {
+	} else if dialect.DBType() == core.ORACLE {
 		if statement.Start != 0 || statement.LimitN != 0 {
 			a = fmt.Sprintf("SELECT %v FROM (SELECT %v,ROWNUM RN FROM (%v) at WHERE ROWNUM <= %d) aat WHERE RN > %d", columnStr, columnStr, a, statement.Start+statement.LimitN, statement.Start)
 		}
 	}
+	if statement.IsForUpdate {
+			a = dialect.ForUpdateSql(a)
+	}
 
 	return
 }