Fix VALUES-aliasing and CHECK TABLE under Turso

- Force the driver's pre-3.33 VALUES-aliasing fallback (prepend an
  explicit UNION ALL header) unconditionally. Turso doesn't propagate
  VALUES implicit column names (column1, column2, ...) through
  INSERT ... SELECT ... FROM (VALUES (...)) subqueries, even though
  top-level SELECT column1 FROM (VALUES(...)) works. Should fix five
  "no such column: columnN" errors.
- CHECK TABLE on missing table: Turso's PRAGMA integrity_check is a
  no-op for unknown tables; add an explicit sqlite_master existence
  probe so testCheckTable's error path fires.

Author: JanJakes

.github/workflows/phpunit-tests-turso.yml

@@ -986,6 +986,63 @@ jobs:
           src = src.replace(old, new, 1)
           open(path, 'w').write(src)
           print('patched hex-literal alias force under Turso')
+
+          # 9. Turso doesn't propagate VALUES row-column aliases (column1,
+          #    column2, ...) through `INSERT ... SELECT ... FROM (VALUES (...))`
+          #    subqueries, even though top-level `SELECT column1 FROM (VALUES
+          #    (...))` works in its own test suite. The driver already has a
+          #    legacy fallback for SQLite < 3.33 that prepends an explicit
+          #    `SELECT NULL AS column1, ... WHERE FALSE UNION ALL ...` so the
+          #    UNION output carries the aliases. Force-enable that fallback
+          #    unconditionally so it applies under Turso too.
+          path = 'src/sqlite/class-wp-pdo-mysql-on-sqlite.php'
+          src = open(path).read()
+          old = "\t\t\t$is_values_naming_supported = version_compare( $this->get_sqlite_version(), '3.33.0', '>=' );"
+          new = "\t\t\t$is_values_naming_supported = false; // Turso: always use UNION ALL header fallback."
+          assert old in src, 'is_values_naming_supported assignment not found'
+          open(path, 'w').write(src.replace(old, new, 1))
+          print('patched VALUES-aliasing fallback to always-on under Turso')
+
+          # 10. CHECK TABLE on a missing table on real SQLite raises from
+          #     `PRAGMA integrity_check(<tbl>)`; on Turso the PRAGMA is a
+          #     no-op for unknown tables, so testCheckTable sees status=OK
+          #     instead of the expected "Table 'missing' doesn't exist"
+          #     error. Check sqlite_master explicitly before the PRAGMA.
+          path = 'src/sqlite/class-wp-pdo-mysql-on-sqlite.php'
+          src = open(path).read()
+          old = (
+              "\t\t\t\t\tcase WP_MySQL_Lexer::CHECK_SYMBOL:\n"
+              "\t\t\t\t\t\t$stmt   = $this->execute_sqlite_query(\n"
+              "\t\t\t\t\t\t\tsprintf( 'PRAGMA integrity_check(%s)', $quoted_table_name )\n"
+              "\t\t\t\t\t\t);\n"
+              "\t\t\t\t\t\t$errors = $stmt->fetchAll( PDO::FETCH_COLUMN );\n"
+              "\t\t\t\t\t\tif ( 'ok' === $errors[0] ) {\n"
+              "\t\t\t\t\t\t\tarray_shift( $errors );\n"
+              "\t\t\t\t\t\t}\n"
+              "\t\t\t\t\t\tbreak;\n"
+          )
+          new = (
+              "\t\t\t\t\tcase WP_MySQL_Lexer::CHECK_SYMBOL:\n"
+              "\t\t\t\t\t\t$exists_stmt = $this->execute_sqlite_query(\n"
+              "\t\t\t\t\t\t\t\"SELECT 1 FROM sqlite_master WHERE type='table' AND name=?\",\n"
+              "\t\t\t\t\t\t\tarray( $table_name )\n"
+              "\t\t\t\t\t\t);\n"
+              "\t\t\t\t\t\tif ( ! $exists_stmt->fetchColumn() ) {\n"
+              "\t\t\t\t\t\t\t$errors = array( \"Table '$table_name' doesn't exist\" );\n"
+              "\t\t\t\t\t\t\tbreak;\n"
+              "\t\t\t\t\t\t}\n"
+              "\t\t\t\t\t\t$stmt   = $this->execute_sqlite_query(\n"
+              "\t\t\t\t\t\t\tsprintf( 'PRAGMA integrity_check(%s)', $quoted_table_name )\n"
+              "\t\t\t\t\t\t);\n"
+              "\t\t\t\t\t\t$errors = $stmt->fetchAll( PDO::FETCH_COLUMN );\n"
+              "\t\t\t\t\t\tif ( 'ok' === $errors[0] ) {\n"
+              "\t\t\t\t\t\t\tarray_shift( $errors );\n"
+              "\t\t\t\t\t\t}\n"
+              "\t\t\t\t\t\tbreak;\n"
+          )
+          assert old in src, 'CHECK TABLE handler not found'
+          open(path, 'w').write(src.replace(old, new, 1))
+          print('patched CHECK TABLE missing-table check')
           PY
 
       - name: Capture failing SQL from the first failing driver test