diff --git a/sqlbuilder/expression_old.go b/sqlbuilder/expression_old.go
index 2c1499f..e8d0aad 100644
--- a/sqlbuilder/expression_old.go
+++ b/sqlbuilder/expression_old.go
@@ -10,20 +10,25 @@ import (
 type intervalExpression struct {
 	expressionInterfaceImpl
 	duration time.Duration
-	negative bool
 }
 
-var intervalSep = ":"
+const intervalSep = ":"
 
 func (c *intervalExpression) Serialize(out *queryData, options ...serializeOption) error {
-	hours := c.duration / time.Hour
-	minutes := (c.duration % time.Hour) / time.Minute
-	sec := (c.duration % time.Minute) / time.Second
-	msec := (c.duration % time.Second) / time.Microsecond
 	out.WriteString("INTERVAL '")
-	if c.negative {
+
+	duration := c.duration
+
+	if duration < 0 {
+		duration = -duration
 		out.WriteString("-")
 	}
+
+	hours := duration / time.Hour
+	minutes := (duration % time.Hour) / time.Minute
+	sec := (duration % time.Minute) / time.Second
+	msec := (duration % time.Second) / time.Microsecond
+
 	out.WriteString(strconv.FormatInt(int64(hours), 10))
 	out.WriteString(intervalSep)
 	out.WriteString(strconv.FormatInt(int64(minutes), 10))
@@ -36,19 +41,16 @@ func (c *intervalExpression) Serialize(out *queryData, options ...serializeOptio
 	return nil
 }
 
-// Interval returns a representation of duration
-// in a form "INTERVAL `hour:min:sec:microsec` HOUR_MICROSECOND"
-func Interval(duration time.Duration) Expression {
-	negative := false
-	if duration < 0 {
-		negative = true
-		duration = -duration
-	}
-	return &intervalExpression{
-		duration: duration,
-		negative: negative,
-	}
-}
+//// Interval returns a representation of duration
+//func Interval(duration time.Duration) Expression {
+//	intervalExp := &intervalExpression{
+//		duration: duration,
+//	}
+//
+//	intervalExp.expressionInterfaceImpl.parent = intervalExp
+//
+//	return intervalExp
+//}
 
 var likeEscaper = strings.NewReplacer("_", "\\_", "%", "\\%")
 
diff --git a/sqlbuilder/func_expression_test.go b/sqlbuilder/func_expression_test.go
index 7e4b9f0..97cdc05 100644
--- a/sqlbuilder/func_expression_test.go
+++ b/sqlbuilder/func_expression_test.go
@@ -31,3 +31,14 @@ func TestCase2(t *testing.T) {
 	assert.NilError(t, err)
 	assert.Equal(t, queryData.buff.String(), `(CASE table3.col1 WHEN $1 THEN table3.col1 + $2 WHEN $3 THEN table3.col1 + $4 ELSE $5 END)`)
 }
+
+func TestInterval(t *testing.T) {
+	query := INTERVAL(`6 years 5 months 4 days 3 hours 2 minutes 1 second`)
+
+	queryData := &queryData{}
+
+	err := query.Serialize(queryData)
+
+	assert.NilError(t, err)
+	assert.Equal(t, queryData.buff.String(), `INTERVAL $1`)
+}
diff --git a/sqlbuilder/time_expression.go b/sqlbuilder/time_expression.go
index c9b22d7..05e6a21 100644
--- a/sqlbuilder/time_expression.go
+++ b/sqlbuilder/time_expression.go
@@ -48,3 +48,25 @@ func (t *timeInterfaceImpl) LtEq(expression TimeExpression) BoolExpression {
 func (t *timeInterfaceImpl) LtEqL(literal string) BoolExpression {
 	return LtEq(t.parent, Literal(literal))
 }
+
+//---------------------------------------------------//
+type prefixTimeExpression struct {
+	expressionInterfaceImpl
+	timeInterfaceImpl
+
+	prefixExpression
+}
+
+func newPrefixTimeExpression(expression Expression, operator string) TimeExpression {
+	timeExpr := prefixTimeExpression{}
+	timeExpr.prefixExpression = newPrefixExpression(expression, operator)
+
+	timeExpr.expressionInterfaceImpl.parent = &timeExpr
+	timeExpr.timeInterfaceImpl.parent = &timeExpr
+
+	return &timeExpr
+}
+
+func INTERVAL(interval string) Expression {
+	return newPrefixTimeExpression(Literal(interval), "INTERVAL")
+}
diff --git a/tests/select_test.go b/tests/select_test.go
index 93558cb..dc88625 100644
--- a/tests/select_test.go
+++ b/tests/select_test.go
@@ -2,7 +2,6 @@ package tests
 
 import (
 	"fmt"
-	"github.com/davecgh/go-spew/spew"
 	"github.com/sub0zero/go-sqlbuilder/sqlbuilder"
 	"github.com/sub0zero/go-sqlbuilder/tests/.test_files/dvd_rental/dvds/model"
 	. "github.com/sub0zero/go-sqlbuilder/tests/.test_files/dvd_rental/dvds/table"
@@ -678,11 +677,10 @@ func TestSelectWithCase(t *testing.T) {
 		ORDER_BY(Payment.PaymentID.ASC()).
 		LIMIT(20)
 
-	queryStr, args, err := query.Sql()
+	queryStr, _, err := query.Sql()
 
 	assert.NilError(t, err)
-	fmt.Println(queryStr)
-	fmt.Println(args)
+	assert.Equal(t, queryStr, `SELECT (CASE payment.staff_id WHEN $1 THEN $2 WHEN $3 THEN $4 WHEN $5 THEN $6 ELSE $7 END) AS "staff_id_num" FROM dvds.payment ORDER BY payment.payment_id ASC LIMIT $8`)
 
 	dest := []struct {
 		StaffIdNum string
@@ -694,9 +692,6 @@ func TestSelectWithCase(t *testing.T) {
 	assert.Equal(t, len(dest), 20)
 	assert.Equal(t, dest[0].StaffIdNum, "TWO")
 	assert.Equal(t, dest[1].StaffIdNum, "ONE")
-
-	spew.Dump(dest)
-
 }
 
 func int16Ptr(i int16) *int16 {