added PreFragment and PostFragment support

select.go

@@ -25,6 +25,8 @@ type SelectQuery struct {
 	ctx       context.Context
 	buildHook BuildHookFunc
 
+	preFragment  string
+	postFragment string
 	selects      []string
 	distinct     bool
 	selectOption string
@@ -88,6 +90,18 @@ func (q *SelectQuery) WithContext(ctx context.Context) *SelectQuery {
 	return q
 }
 
+// PreFragment sets SQL fragment that should be prepended before the select query (e.g. WITH clause).
+func (s *SelectQuery) PreFragment(fragment string) *SelectQuery {
+	s.preFragment = fragment
+	return s
+}
+
+// PostFragment sets SQL fragment that should be appended at the end of the select query.
+func (s *SelectQuery) PostFragment(fragment string) *SelectQuery {
+	s.postFragment = fragment
+	return s
+}
+
 // Select specifies the columns to be selected.
 // Column names will be automatically quoted.
 func (s *SelectQuery) Select(cols ...string) *SelectQuery {
@@ -265,13 +279,15 @@ func (s *SelectQuery) Build() *Query {
 	qb := s.builder.QueryBuilder()
 
 	clauses := []string{
+		s.preFragment,
 		qb.BuildSelect(s.selects, s.distinct, s.selectOption),
 		qb.BuildFrom(s.from),
 		qb.BuildJoin(s.join, params),
 		qb.BuildWhere(s.where, params),
 		qb.BuildGroupBy(s.groupBy),
 		qb.BuildHaving(s.having, params),
 	}
+
 	sql := ""
 	for _, clause := range clauses {
 		if clause != "" {
@@ -282,7 +298,13 @@ func (s *SelectQuery) Build() *Query {
 			}
 		}
 	}
+
 	sql = qb.BuildOrderByAndLimit(sql, s.orderBy, s.limit, s.offset)
+
+	if s.postFragment != "" {
+		sql += " " + s.postFragment
+	}
+
 	if union := qb.BuildUnion(s.union, params); union != "" {
 		sql = fmt.Sprintf("(%v) %v", sql, union)
 	}
@@ -377,6 +399,8 @@ func (s *SelectQuery) Column(a interface{}) error {
 
 // QueryInfo represents a debug/info struct with exported SelectQuery fields.
 type QueryInfo struct {
+	PreFragment  string
+	PostFragment string
 	Builder      Builder
 	Selects      []string
 	Distinct     bool
@@ -400,6 +424,8 @@ type QueryInfo struct {
 func (s *SelectQuery) Info() *QueryInfo {
 	return &QueryInfo{
 		Builder:      s.builder,
+		PreFragment:  s.preFragment,
+		PostFragment: s.postFragment,
 		Selects:      s.selects,
 		Distinct:     s.distinct,
 		SelectOption: s.selectOption,

select_test.go

@@ -23,6 +23,8 @@ func TestSelectQuery(t *testing.T) {
 
 	// a full select query
 	q = db.Select("id", "name").
+		PreFragment("pre").
+		PostFragment("post").
 		AndSelect("age").
 		Distinct(true).
 		SelectOption("CALC").
@@ -46,18 +48,18 @@ func TestSelectQuery(t *testing.T) {
 		AndBind(Params{"age": 30}).
 		Build()
 
-	expected = "SELECT DISTINCT CALC `id`, `name`, `age` FROM `users` INNER JOIN `profile` ON user.id=profile.id LEFT JOIN `team` RIGHT JOIN `dept` WHERE ((age>30) AND (status=1)) OR (type=2) GROUP BY `id`, `age` HAVING ((id>10) AND (id<20)) OR (type=3) ORDER BY `age` DESC, `type`, `id` LIMIT 10 OFFSET 20"
+	expected = "pre SELECT DISTINCT CALC `id`, `name`, `age` FROM `users` INNER JOIN `profile` ON user.id=profile.id LEFT JOIN `team` RIGHT JOIN `dept` WHERE ((age>30) AND (status=1)) OR (type=2) GROUP BY `id`, `age` HAVING ((id>10) AND (id<20)) OR (type=3) ORDER BY `age` DESC, `type`, `id` LIMIT 10 OFFSET 20 post"
 	assert.Equal(t, q.SQL(), expected, "t3")
 	assert.Equal(t, len(q.Params()), 2, "t4")
 
 	q3 := db.Select().AndBind(Params{"id": 1}).Build()
 	assert.Equal(t, len(q3.Params()), 1)
 
 	// union
-	q1 := db.Select().From("users").Build()
-	q2 := db.Select().From("posts").Build()
-	q = db.Select().From("profiles").Union(q1).UnionAll(q2).Build()
-	expected = "(SELECT * FROM `profiles`) UNION (SELECT * FROM `users`) UNION ALL (SELECT * FROM `posts`)"
+	q1 := db.Select().From("users").PreFragment("pre_q1").Build()
+	q2 := db.Select().From("posts").PostFragment("post_q2").Build()
+	q = db.Select().From("profiles").Union(q1).UnionAll(q2).PreFragment("pre").PostFragment("post").Build()
+	expected = "(pre SELECT * FROM `profiles` post) UNION (pre_q1 SELECT * FROM `users`) UNION ALL (SELECT * FROM `posts` post_q2)"
 	assert.Equal(t, q.SQL(), expected, "t5")
 }