merge: [Masterminds#316](Masterminds#316) [Masterminds#331](Mastermin…

…ds#331)

select.go

@@ -326,6 +326,13 @@ func (b SelectBuilder) Columns(columns ...string) SelectBuilder {
 	return builder.Extend(b, "Columns", parts).(SelectBuilder)
 }
 
+// RemoveColumns remove all columns from query.
+// Must add a new column with Column or Columns methods, otherwise
+// return a error.
+func (b SelectBuilder) RemoveColumns() SelectBuilder {
+	return builder.Delete(b, "Columns").(SelectBuilder)
+}
+
 // Column adds a result column to the query.
 // Unlike Columns, Column accepts args which will be bound to placeholders in
 // the columns string, for example:

select_test.go

@@ -312,6 +312,22 @@ func TestCTEErrorBubblesUp(t *testing.T) {
 	assert.Error(t, err)
 }
 
+func TestSelectJoinClausePlaceholderNumbering(t *testing.T) {
+	subquery := Select("a").Where(Eq{"b": 2}).PlaceholderFormat(Dollar)
+
+	sql, args, err := Select("t1.a").
+		From("t1").
+		Where(Eq{"a": 1}).
+		JoinClause(subquery.Prefix("JOIN (").Suffix(") t2 ON (t1.a = t2.a)")).
+		PlaceholderFormat(Dollar).
+		FinalizeSql()
+	assert.NoError(t, err)
+
+	expectedSql := "SELECT t1.a FROM t1 JOIN ( SELECT a WHERE b = $1 ) t2 ON (t1.a = t2.a) WHERE a = $2"
+	assert.Equal(t, expectedSql, sql)
+	assert.Equal(t, []interface{}{2, 1}, args)
+}
+
 func ExampleSelect() {
 	Select("id", "created", "first_name").From("users") // ... continue building up your query
 
@@ -468,3 +484,13 @@ func ExampleSelectBuilder_ToSql() {
 		// scan...
 	}
 }
+
+func TestRemoveColumns(t *testing.T) {
+	query := Select("id").
+		From("users").
+		RemoveColumns()
+	query = query.Columns("name")
+	sql, _, err := query.ToSql()
+	assert.NoError(t, err)
+	assert.Equal(t, "SELECT name FROM users", sql)
+}