Drop support for NOW() and IF.

Per: huandu#85 (review)

insert_test.go

@@ -53,8 +53,8 @@ func ExampleInsertBuilder() {
 	ib := NewInsertBuilder()
 	ib.InsertInto("demo.user")
 	ib.Cols("id", "name", "status", "created_at", "updated_at")
-	ib.Values(1, "Huan Du", 1, Raw("UNIX_TIMESTAMP(NOW())"), Now())
-	ib.Values(2, "Charmy Liu", 1, 1234567890, Now())
+	ib.Values(1, "Huan Du", 1, Raw("UNIX_TIMESTAMP(NOW())"), Raw("NOW()"))
+	ib.Values(2, "Charmy Liu", 1, 1234567890, Raw("NOW()"))
 
 	sql, args := ib.Build()
 	fmt.Println(sql)
@@ -69,8 +69,8 @@ func ExampleInsertBuilder_insertIgnore() {
 	ib := NewInsertBuilder()
 	ib.InsertIgnoreInto("demo.user")
 	ib.Cols("id", "name", "status", "created_at", "updated_at")
-	ib.Values(1, "Huan Du", 1, Raw("UNIX_TIMESTAMP(NOW())"), Now())
-	ib.Values(2, "Charmy Liu", 1, 1234567890, Now())
+	ib.Values(1, "Huan Du", 1, Raw("UNIX_TIMESTAMP(NOW())"), Raw("NOW()"))
+	ib.Values(2, "Charmy Liu", 1, 1234567890, Raw("NOW()"))
 
 	sql, args := ib.Build()
 	fmt.Println(sql)
@@ -117,8 +117,8 @@ func ExampleInsertBuilder_replaceInto() {
 	ib := NewInsertBuilder()
 	ib.ReplaceInto("demo.user")
 	ib.Cols("id", "name", "status", "created_at", "updated_at")
-	ib.Values(1, "Huan Du", 1, Raw("UNIX_TIMESTAMP(NOW())"), Now())
-	ib.Values(2, "Charmy Liu", 1, 1234567890, Now())
+	ib.Values(1, "Huan Du", 1, Raw("UNIX_TIMESTAMP(NOW())"), Raw("NOW()"))
+	ib.Values(2, "Charmy Liu", 1, 1234567890, Raw("NOW()"))
 
 	sql, args := ib.Build()
 	fmt.Println(sql)

modifiers.go

@@ -72,11 +72,6 @@ func Raw(expr string) interface{} {
 	return rawArgs{expr}
 }
 
-// Now returns a raw value comprising the NOW() function.
-func Now() interface{} {
-	return Raw("NOW()")
-}
-
 type listArgs struct {
 	args []interface{}
 }

update.go

@@ -17,7 +17,6 @@ const (
 	updateMarkerAfterWhere
 	updateMarkerAfterOrderBy
 	updateMarkerAfterLimit
-	updateMarkerAfterIf
 )
 
 // NewUpdateBuilder creates a new UPDATE builder.
@@ -47,7 +46,6 @@ type UpdateBuilder struct {
 	orderByCols []string
 	order       string
 	limit       int
-	ifExprs     []string
 
 	args *Args
 
@@ -159,13 +157,6 @@ func (ub *UpdateBuilder) Limit(limit int) *UpdateBuilder {
 	return ub
 }
 
-// If sets IF expressions for UPDATE.
-func (ub *UpdateBuilder) If(andExpr ...string) *UpdateBuilder {
-	ub.ifExprs = append(ub.ifExprs, andExpr...)
-	ub.marker = updateMarkerAfterIf
-	return ub
-}
-
 // String returns the compiled UPDATE string.
 func (ub *UpdateBuilder) String() string {
 	s, _ := ub.Build()
@@ -216,12 +207,6 @@ func (ub *UpdateBuilder) BuildWithFlavor(flavor Flavor, initialArg ...interface{
 		ub.injection.WriteTo(buf, updateMarkerAfterLimit)
 	}
 
-	if len(ub.ifExprs) > 0 {
-		buf.WriteString(" IF ")
-		buf.WriteString(strings.Join(ub.ifExprs, " AND "))
-		ub.injection.WriteTo(buf, updateMarkerAfterIf)
-	}
-
 	return ub.args.CompileWithFlavor(buf.String(), flavor, initialArg...)
 }
 

update_test.go

@@ -44,18 +44,14 @@ func ExampleUpdateBuilder() {
 		"modified_at > created_at + "+ub.Var(86400), // It's allowed to write arbitrary SQL.
 	)
 	ub.OrderBy("id").Asc()
-	ub.If(
-		ub.E("type", "sys"),
-		ub.E("ready", true),
-	)
 
 	sql, args := ub.Build()
 	fmt.Println(sql)
 	fmt.Println(args)
 
 	// Output:
-	// UPDATE demo.user SET type = ?, credit = credit + 1, modified_at = UNIX_TIMESTAMP(NOW()) WHERE id > ? AND name LIKE ? AND (id_card IS NULL OR status IN (?, ?, ?)) AND modified_at > created_at + ? ORDER BY id ASC IF type = ? AND ready = ?
-	// [sys 1234 %Du 1 2 5 86400 sys true]
+	// UPDATE demo.user SET type = ?, credit = credit + 1, modified_at = UNIX_TIMESTAMP(NOW()) WHERE id > ? AND name LIKE ? AND (id_card IS NULL OR status IN (?, ?, ?)) AND modified_at > created_at + ? ORDER BY id ASC
+	// [sys 1234 %Du 1 2 5 86400]
 }
 
 func TestUpdateAssignments(t *testing.T) {