diff options
Diffstat (limited to 'lib/sqlalchemy/sql')
| -rw-r--r-- | lib/sqlalchemy/sql/compiler.py | 61 | ||||
| -rw-r--r-- | lib/sqlalchemy/sql/dml.py | 34 |
2 files changed, 86 insertions, 9 deletions
diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py index b0f0807d6..9ed75ca06 100644 --- a/lib/sqlalchemy/sql/compiler.py +++ b/lib/sqlalchemy/sql/compiler.py @@ -2146,10 +2146,9 @@ class SQLCompiler(Compiled): MySQL and MSSQL override this. """ - return "FROM " + ', '.join( - t._compiler_dispatch(self, asfrom=True, - fromhints=from_hints, **kw) - for t in extra_froms) + raise NotImplementedError( + "This backend does not support multiple-table " + "criteria within UPDATE") def visit_update(self, update_stmt, asfrom=False, **kw): toplevel = not self.stack @@ -2232,6 +2231,25 @@ class SQLCompiler(Compiled): def _key_getters_for_crud_column(self): return crud._key_getters_for_crud_column(self, self.statement) + def delete_extra_from_clause(self, update_stmt, + from_table, extra_froms, + from_hints, **kw): + """Provide a hook to override the generation of an + DELETE..FROM clause. + + This can be used to implement DELETE..USING for example. + + MySQL and MSSQL override this. + + """ + raise NotImplementedError( + "This backend does not support multiple-table " + "criteria within DELETE") + + def delete_table_clause(self, delete_stmt, from_table, + extra_froms): + return from_table._compiler_dispatch(self, asfrom=True, iscrud=True) + def visit_delete(self, delete_stmt, asfrom=False, **kw): toplevel = not self.stack @@ -2241,6 +2259,8 @@ class SQLCompiler(Compiled): crud._setup_crud_params(self, delete_stmt, crud.ISDELETE, **kw) + extra_froms = delete_stmt._extra_froms + text = "DELETE " if delete_stmt._prefixes: @@ -2248,12 +2268,14 @@ class SQLCompiler(Compiled): delete_stmt._prefixes, **kw) text += "FROM " - table_text = delete_stmt.table._compiler_dispatch( - self, asfrom=True, iscrud=True) + table_text = self.delete_table_clause(delete_stmt, delete_stmt.table, + extra_froms) if delete_stmt._hints: dialect_hints, table_text = self._setup_crud_hints( delete_stmt, table_text) + else: + dialect_hints = None text += table_text @@ -2262,6 +2284,15 @@ class SQLCompiler(Compiled): text += " " + self.returning_clause( delete_stmt, delete_stmt._returning) + if extra_froms: + extra_from_text = self.delete_extra_from_clause( + delete_stmt, + delete_stmt.table, + extra_froms, + dialect_hints, **kw) + if extra_from_text: + text += " " + extra_from_text + if delete_stmt._whereclause is not None: t = delete_stmt._whereclause._compiler_dispatch(self, **kw) if t: @@ -2324,6 +2355,24 @@ class StrSQLCompiler(SQLCompiler): return 'RETURNING ' + ', '.join(columns) + def update_from_clause(self, update_stmt, + from_table, extra_froms, + from_hints, + **kw): + return "FROM " + ', '.join( + t._compiler_dispatch(self, asfrom=True, + fromhints=from_hints, **kw) + for t in extra_froms) + + def delete_extra_from_clause(self, update_stmt, + from_table, extra_froms, + from_hints, + **kw): + return ', ' + ', '.join( + t._compiler_dispatch(self, asfrom=True, + fromhints=from_hints, **kw) + for t in extra_froms) + class DDLCompiler(Compiled): diff --git a/lib/sqlalchemy/sql/dml.py b/lib/sqlalchemy/sql/dml.py index 958e9bfb1..6c8c550b4 100644 --- a/lib/sqlalchemy/sql/dml.py +++ b/lib/sqlalchemy/sql/dml.py @@ -656,7 +656,7 @@ class Update(ValuesBase): ) .. versionchanged:: 0.7.4 - The WHERE clause can refer to multiple tables. + The WHERE clause of UPDATE can refer to multiple tables. :param values: Optional dictionary which specifies the ``SET`` conditions of the @@ -768,8 +768,6 @@ class Update(ValuesBase): @property def _extra_froms(self): - # TODO: this could be made memoized - # if the memoization is reset on each generative call. froms = [] seen = {self.table} @@ -811,6 +809,23 @@ class Delete(UpdateBase): condition of the ``DELETE`` statement. Note that the :meth:`~Delete.where()` generative method may be used instead. + The WHERE clause can refer to multiple tables. + For databases which support this, a ``DELETE..USING`` or similar + clause will be generated. The statement + will fail on databases that don't have support for multi-table + delete statements. A SQL-standard method of referring to + additional tables in the WHERE clause is to use a correlated + subquery:: + + users.delete().where( + users.c.name==select([addresses.c.email_address]).\ + where(addresses.c.user_id==users.c.id).\ + as_scalar() + ) + + .. versionchanged:: 1.2.0 + The WHERE clause of DELETE can refer to multiple tables. + .. seealso:: :ref:`deletes` - SQL Expression Tutorial @@ -846,6 +861,19 @@ class Delete(UpdateBase): else: self._whereclause = _literal_as_text(whereclause) + @property + def _extra_froms(self): + froms = [] + seen = {self.table} + + if self._whereclause is not None: + for item in _from_objects(self._whereclause): + if not seen.intersection(item._cloned_set): + froms.append(item) + seen.update(item._cloned_set) + + return froms + def _copy_internals(self, clone=_clone, **kw): # TODO: coverage self._whereclause = clone(self._whereclause, **kw) |