enable UPDATE..FROM for SQLite

The SQLite dialect now supports UPDATE..FROM syntax, for UPDATE statements
that may refer to additional tables within the WHERE criteria of the
statement without the need to use subqueries. This syntax is invoked
automatically when using the :class:`_dml.Update` construct when more than
one table or other entity or selectable is used.

Fixes: #7185
Change-Id: I27e94ace9ff761cc45e652fa1abff8cd1f42fec5

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/sqlite/base.py b/lib/sqlalchemy/dialects/sqlite/base.py
index 222f3a137..88c6dbe18 100644
--- a/lib/sqlalchemy/dialects/sqlite/base.py
+++ b/lib/sqlalchemy/dialects/sqlite/base.py
@@ -1381,6 +1381,15 @@ class SQLiteCompiler(compiler.SQLCompiler):
         # sqlite has no "FOR UPDATE" AFAICT
         return ""
 
+    def update_from_clause(
+        self, update_stmt, from_table, extra_froms, from_hints, **kw
+    ):
+        kw["asfrom"] = True
+        return "FROM " + ", ".join(
+            t._compiler_dispatch(self, fromhints=from_hints, **kw)
+            for t in extra_froms
+        )
+
     def visit_is_distinct_from_binary(self, binary, operator, **kw):
         return "%s IS NOT %s" % (
             self.process(binary.left),
@@ -1933,6 +1942,7 @@ class SQLiteDialect(default.DefaultDialect):
     insert_returning = True
     update_returning = True
     delete_returning = True
+    update_returning_multifrom = True
 
     default_paramstyle = "qmark"
     execution_ctx_cls = SQLiteExecutionContext