From 31736ec13e472a759dd64b4678438dc006d501c7 Mon Sep 17 00:00:00 2001
From: sub0Zero <zer0.sub@protonmail.com>
Date: Sun, 17 Mar 2019 20:41:03 +0100
Subject: [PATCH] Add support for column alias.

---
 sqlbuilder/column.go    | 14 +++++++++++++-
 tests/generator_test.go | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/sqlbuilder/column.go b/sqlbuilder/column.go
index aff18ba..e6ebf6c 100644
--- a/sqlbuilder/column.go
+++ b/sqlbuilder/column.go
@@ -16,6 +16,8 @@ type Column interface {
 	isProjectionInterface
 	isExpressionInterface
 
+	As(alias string) Column
+
 	Name() string
 	// Serialization for use in column lists
 	SerializeSqlForColumnList(out *bytes.Buffer) error
@@ -74,6 +76,14 @@ type baseColumn struct {
 	name     string
 	nullable NullableColumn
 	table    string
+	alias    string
+}
+
+func (c *baseColumn) As(alias string) Column {
+	newBaseColumn := *c
+	newBaseColumn.alias = alias
+
+	return &newBaseColumn
 }
 
 func (c *baseColumn) Name() string {
@@ -89,7 +99,9 @@ func (c *baseColumn) SerializeSqlForColumnList(out *bytes.Buffer) error {
 
 	c.SerializeSql(out)
 
-	if c.table != "" {
+	if c.alias != "" {
+		_, _ = out.WriteString(" AS \"" + c.alias + "\"")
+	} else if c.table != "" {
 		_, _ = out.WriteString(" AS \"" + c.table + "." + c.name + "\"")
 	}
 
diff --git a/tests/generator_test.go b/tests/generator_test.go
index 894d8f6..9a4450e 100644
--- a/tests/generator_test.go
+++ b/tests/generator_test.go
@@ -328,6 +328,42 @@ func TestSelectSelfJoin(t *testing.T) {
 	assert.Equal(t, len(theSameLengthFilms), 6972)
 }
 
+func TestSelectAliasColumn(t *testing.T) {
+	f1 := Film.As("f1")
+	f2 := Film.As("f2")
+
+	type thesameLengthFilms struct {
+		Title1 string
+		Title2 string
+		Length int16
+	}
+
+	query := f1.
+		InnerJoinOn(f2, f1.FilmID.Neq(f2.FilmID).And(f1.Length.Eq(f2.Length))).
+		Select(f1.Title.As("thesame_length_films.title1"),
+			f2.Title.As("thesame_length_films.title2"),
+			f1.Length.As("thesame_length_films.length")).
+		OrderBy(f1.Length.Asc()).
+		Limit(1000)
+
+	queryStr, err := query.String()
+
+	assert.NilError(t, err)
+
+	fmt.Println(queryStr)
+
+	films := []thesameLengthFilms{}
+
+	err = query.Execute(db, &films)
+
+	assert.NilError(t, err)
+
+	//spew.Dump(films)
+
+	assert.Equal(t, len(films), 1000)
+	assert.DeepEqual(t, films[0], thesameLengthFilms{"Ridgemont Submarine", "Iron Moon", 46})
+}
+
 func int32Ptr(i int32) *int32 {
 	return &i
 }