Merge pull request #793 from erizocosmico/fix/having-orderby

sql/analyzer: fix order by resolution for all nodes

Author: ajnavarro

engine_test.go

@@ -1433,6 +1433,27 @@ var queries = []struct {
 		`SELECT CASE WHEN NULL THEN "yes" ELSE "no" END AS test`,
 		[]sql.Row{{"no"}},
 	},
+	{
+		`SELECT
+			table_schema,
+			table_name,
+			CASE
+				WHEN table_type = 'BASE TABLE' THEN
+					CASE
+						WHEN table_schema = 'mysql'
+							OR table_schema = 'performance_schema' THEN 'SYSTEM TABLE'
+						ELSE 'TABLE'
+					END
+				WHEN table_type = 'TEMPORARY' THEN 'LOCAL_TEMPORARY'
+				ELSE table_type
+			END AS TABLE_TYPE
+		FROM information_schema.tables
+		WHERE table_schema = 'mydb'
+			AND table_name = 'mytable'
+		HAVING table_type IN ('TABLE', 'VIEW')
+		ORDER BY table_type, table_schema, table_name`,
+		[]sql.Row{{"mydb", "mytable", "TABLE"}},
+	},
 }
 
 func TestQueries(t *testing.T) {

sql/analyzer/resolve_orderby.go

@@ -166,8 +166,18 @@ func pushSortDown(sort *plan.Sort) (sql.Node, error) {
 	case *plan.ResolvedTable:
 		return child, nil
 	default:
-		// Can't do anything here, there should be either a project or a groupby
-		// below an order by.
+		children := child.Children()
+		if len(children) == 1 {
+			newChild, err := pushSortDown(plan.NewSort(sort.SortFields, children[0]))
+			if err != nil {
+				return nil, err
+			}
+
+			return child.WithChildren(newChild)
+		}
+
+		// If the child has more than one children we don't know to which side
+		// the sort must be pushed down.
 		return nil, errSortPushdown.New(child)
 	}
 }