From d12b37f90ef538300f8ebb454eec75beccbe929f Mon Sep 17 00:00:00 2001 From: inytar Date: Mon, 30 Oct 2017 12:01:49 -0400 Subject: Allow delete where clause to refer multiple tables. Implemented "DELETE..FROM" syntax for Postgresql, MySQL, MS SQL Server (as well as within the unsupported Sybase dialect) in a manner similar to how "UPDATE..FROM" works. A DELETE statement that refers to more than one table will switch into "multi-table" mode and render the appropriate "USING" or multi-table "FROM" clause as understood by the database. Pull request courtesy Pieter Mulder. For SQL syntaxes see: Postgresql: https://www.postgresql.org/docs/current/static/sql-delete.html MySQL: https://dev.mysql.com/doc/refman/5.7/en/delete.html#multiple-table_syntax MSSQL: https://docs.microsoft.com/en-us/sql/t-sql/statements/delete-transact-sql Sybase: http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.infocenter.dc00801.1510/html/iqrefso/X315721.htm Co-authored by: Mike Bayer Change-Id: I6dfd57b49e44a095d076dc493cd2360bb5d920d3 Pull-request: https://github.com/zzzeek/sqlalchemy/pull/392 Fixes: #959 --- lib/sqlalchemy/dialects/mysql/base.py | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'lib/sqlalchemy/dialects/mysql/base.py') diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py index bee62b76f..09f8a2a0e 100644 --- a/lib/sqlalchemy/dialects/mysql/base.py +++ b/lib/sqlalchemy/dialects/mysql/base.py @@ -1102,6 +1102,24 @@ class MySQLCompiler(compiler.SQLCompiler): extra_froms, from_hints, **kw): return None + def delete_table_clause(self, delete_stmt, from_table, + extra_froms): + """If we have extra froms make sure we render any alias as hint.""" + ashint = False + if extra_froms: + ashint = True + return from_table._compiler_dispatch( + self, asfrom=True, iscrud=True, ashint=ashint + ) + + def delete_extra_from_clause(self, delete_stmt, from_table, + extra_froms, from_hints, **kw): + """Render the DELETE .. USING clause specific to MySQL.""" + return "USING " + ', '.join( + t._compiler_dispatch(self, asfrom=True, + fromhints=from_hints, **kw) + for t in [from_table] + extra_froms) + class MySQLDDLCompiler(compiler.DDLCompiler): def get_column_specification(self, column, **kw): -- cgit v1.2.1