1 files changed, 63 insertions, 0 deletions
diff --git a/tests/fixtures/optimizer/merge_derived_tables.sql b/tests/fixtures/optimizer/merge_derived_tables.sql
new file mode 100644
index 0000000..c5aa7e9
--- /dev/null
+++ b/tests/fixtures/optimizer/merge_derived_tables.sql
@@ -0,0 +1,63 @@
+-- Simple
+SELECT a, b FROM (SELECT a, b FROM x);
+SELECT x.a AS a, x.b AS b FROM x AS x;
+
+-- Inner table alias is merged
+SELECT a, b FROM (SELECT a, b FROM x AS q) AS r;
+SELECT q.a AS a, q.b AS b FROM x AS q;
+
+-- Double nesting
+SELECT a, b FROM (SELECT a, b FROM (SELECT a, b FROM x));
+SELECT x.a AS a, x.b AS b FROM x AS x;
+
+-- WHERE clause is merged
+SELECT a, SUM(b) FROM (SELECT a, b FROM x WHERE a > 1) GROUP BY a;
+SELECT x.a AS a, SUM(x.b) AS "_col_1" FROM x AS x WHERE x.a > 1 GROUP BY x.a;
+
+-- Outer query has join
+SELECT a, c FROM (SELECT a, b FROM x WHERE a > 1) AS x JOIN y ON x.b = y.b;
+SELECT x.a AS a, y.c AS c FROM x AS x JOIN y AS y ON x.b = y.b WHERE x.a > 1;
+
+-- Join on derived table
+SELECT a, c FROM x JOIN (SELECT b, c FROM y) AS y ON x.b = y.b;
+SELECT x.a AS a, y.c AS c FROM x AS x JOIN y AS y ON x.b = y.b;
+
+-- Inner query has a join
+SELECT a, c FROM (SELECT a, c FROM x JOIN y ON x.b = y.b);
+SELECT x.a AS a, y.c AS c FROM x AS x JOIN y AS y ON x.b = y.b;
+
+-- Inner query has conflicting name in outer query
+SELECT a, c FROM (SELECT q.a, q.b FROM x AS q) AS x JOIN y AS q ON x.b = q.b;
+SELECT q_2.a AS a, q.c AS c FROM x AS q_2 JOIN y AS q ON q_2.b = q.b;
+
+-- Inner query has conflicting name in joined source
+SELECT x.a, q.c FROM (SELECT a, x.b FROM x JOIN y AS q ON x.b = q.b) AS x JOIN y AS q ON x.b = q.b;
+SELECT x.a AS a, q.c AS c FROM x AS x JOIN y AS q_2 ON x.b = q_2.b JOIN y AS q ON x.b = q.b;
+
+-- Inner query has multiple conflicting names
+SELECT x.a, q.c, r.c FROM (SELECT q.a, r.b FROM x AS q JOIN y AS r ON q.b = r.b) AS x JOIN y AS q ON x.b = q.b JOIN y AS r ON x.b = r.b;
+SELECT q_2.a AS a, q.c AS c, r.c AS c FROM x AS q_2 JOIN y AS r_2 ON q_2.b = r_2.b JOIN y AS q ON r_2.b = q.b JOIN y AS r ON r_2.b = r.b;
+
+-- Inner queries have conflicting names with each other
+SELECT r.b FROM (SELECT b FROM x AS x) AS q JOIN (SELECT b FROM x) AS r ON q.b = r.b;
+SELECT x_2.b AS b FROM x AS x JOIN x AS x_2 ON x.b = x_2.b;
+
+-- WHERE clause in joined derived table is merged
+SELECT x.a, y.c FROM x JOIN (SELECT b, c FROM y WHERE c > 1) AS y;
+SELECT x.a AS a, y.c AS c FROM x AS x JOIN y AS y WHERE y.c > 1;
+
+-- WHERE clause in outer joined derived table is merged to ON clause
+SELECT x.a, y.c FROM x LEFT JOIN (SELECT b, c FROM y WHERE c > 1) AS y;
+SELECT x.a AS a, y.c AS c FROM x AS x LEFT JOIN y AS y ON y.c > 1;
+
+-- Comma JOIN in outer query
+SELECT x.a, y.c FROM (SELECT a FROM x) AS x, (SELECT c FROM y) AS y;
+SELECT x.a AS a, y.c AS c FROM x AS x, y AS y;
+
+-- Comma JOIN in inner query
+SELECT x.a, x.c FROM (SELECT x.a, z.c FROM x, y AS z) AS x;
+SELECT x.a AS a, z.c AS c FROM x AS x CROSS JOIN y AS z;
+
+-- (Regression) Column in ORDER BY
+SELECT * FROM (SELECT * FROM (SELECT * FROM x)) ORDER BY a LIMIT 1;
+SELECT x.a AS a, x.b AS b FROM x AS x ORDER BY x.a LIMIT 1;