fix MySQLSchemaTool FK introspection under ONLY_FULL_GROUP_BY

src/Tools/Toolkits/MySQL/MySQLSchemaTool.php

@@ -237,6 +237,8 @@ protected function getRelationships(): array
             $params = array_merge($this->tables, $this->tables);
         }
 
+        // ORDINAL_POSITION must appear in the SELECT list: MySQL/MariaDB with
+        // ONLY_FULL_GROUP_BY reject DISTINCT + ORDER BY on non-selected columns.
         $stmt = $this->pdo->prepare("
             SELECT DISTINCT
                 kcu.CONSTRAINT_NAME,
@@ -245,7 +247,8 @@ protected function getRelationships(): array
                 kcu.REFERENCED_TABLE_NAME as target_table,
                 kcu.REFERENCED_COLUMN_NAME as target_column,
                 rc.UPDATE_RULE,
-                rc.DELETE_RULE
+                rc.DELETE_RULE,
+                kcu.ORDINAL_POSITION
             FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu
             JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS rc
                 ON kcu.CONSTRAINT_NAME = rc.CONSTRAINT_NAME

tests/Tools/Toolkits/MySQL/MySQLSchemaToolTest.php

@@ -158,6 +158,18 @@ public function test_lookups_are_scoped_to_the_current_database(): void
         }
     }
 
+    public function test_relationships_query_selects_ordinal_position_for_strict_sql_mode(): void
+    {
+        (new MySQLSchemaTool($this->informationSchema()))();
+
+        $sql = $this->lookup('KEY_COLUMN_USAGE')['sql'];
+
+        $this->assertMatchesRegularExpression(
+            '/SELECT DISTINCT\b[\s\S]*\bkcu\.ORDINAL_POSITION\b[\s\S]*\bORDER BY\b[\s\S]*\bkcu\.ORDINAL_POSITION\b/i',
+            $sql
+        );
+    }
+
     public function test_tool_takes_no_input(): void
     {
         $tool = new MySQLSchemaTool($this->createMock(PDO::class));