fix(compiler): Validate UNION ... ORDER BY (#2446)

Author: kyleconroy

internal/compiler/output_columns.go

@@ -65,6 +65,7 @@ func (c *Compiler) outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, er
 		targets = n.ReturningList
 	case *ast.SelectStmt:
 		targets = n.TargetList
+		isUnion := len(targets.Items) == 0 && n.Larg != nil
 
 		if n.GroupClause != nil {
 			for _, item := range n.GroupClause.Items {
@@ -77,7 +78,7 @@ func (c *Compiler) outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, er
 		if c.conf.StrictOrderBy != nil {
 			validateOrderBy = *c.conf.StrictOrderBy
 		}
-		if validateOrderBy {
+		if !isUnion && validateOrderBy {
 			if n.SortClause != nil {
 				for _, item := range n.SortClause.Items {
 					sb, ok := item.(*ast.SortBy)
@@ -110,7 +111,7 @@ func (c *Compiler) outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, er
 
 		// For UNION queries, targets is empty and we need to look for the
 		// columns in Largs.
-		if len(targets.Items) == 0 && n.Larg != nil {
+		if isUnion {
 			return c.outputColumns(qc, n.Larg)
 		}
 	case *ast.CallStmt:

internal/endtoend/testdata/order_by_union/mysql/go/db.go

@@ -0,0 +1,14 @@
+CREATE TABLE authors (
+  name text      NOT NULL,
+  bio  text
+);
+
+CREATE TABLE people (
+  first_name text      NOT NULL
+);
+
+-- name: ListAuthorsUnion :many
+SELECT name as foo FROM authors
+UNION
+SELECT first_name as foo FROM people
+ORDER BY foo;

internal/endtoend/testdata/order_by_union/mysql/go/models.go

@@ -0,0 +1,12 @@
+{
+	"version": "1",
+	"packages": [
+		{
+			"path": "go",
+			"engine": "mysql",
+			"name": "querytest",
+			"schema": "query.sql",
+			"queries": "query.sql"
+		}
+	]
+}

internal/endtoend/testdata/order_by_union/mysql/go/query.sql.go

@@ -0,0 +1,15 @@
+CREATE TABLE authors (
+  id   BIGSERIAL PRIMARY KEY,
+  name text      NOT NULL,
+  bio  text
+);
+
+CREATE TABLE people (
+  first_name text      NOT NULL
+);
+
+-- name: ListAuthorsUnion :many
+SELECT name as foo FROM authors
+UNION
+SELECT first_name as foo FROM people
+ORDER BY foo;