LibSQL+SQLServer: Implement first cut of SELECT ... ORDER BY foo

Ordering is done by replacing the straight Vector holding the query
result in the SQLResult object with a dedicated Vector subclass that
inserts result rows according to their sort key using a binary search.
This is done in the ResultSet class.

There are limitations:
- "SELECT ... ORDER BY 1" (or 2 or 3 etc) is supposed to sort by the
n-th result column. This doesn't work yet
- "SELECT ... column-expression alias ... ORDER BY alias" is supposed to
sort by the column with the given alias. This doesn't work yet

What does work however is something like
```SELECT foo FROM bar SORT BY quux```
i.e. sorted by a column not in the result set. Once functions are
supported it should be possible to sort by random functions.

1 files changed, 29 insertions, 0 deletions

diff --git a/Userland/Libraries/LibSQL/ResultSet.h b/Userland/Libraries/LibSQL/ResultSet.h
new file mode 100644
index 0000000000..8a9e60399c
--- /dev/null
+++ b/Userland/Libraries/LibSQL/ResultSet.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2022, Jan de Visser <jan@de-visser.net>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Vector.h>
+#include <LibSQL/Tuple.h>
+#include <LibSQL/Type.h>
+
+namespace SQL {
+
+struct ResultRow {
+    Tuple row;
+    Tuple sort_key;
+};
+
+class ResultSet : public Vector<ResultRow> {
+public:
+    ResultSet() = default;
+    void insert_row(Tuple const& row, Tuple const& sort_key);
+
+private:
+    size_t binary_search(Tuple const& sort_key, size_t low, size_t high);
+};
+
+}