ah, if you dont want AUTO_INCREMENT in your create statements, yeah that would be a "feature enhancement" at the moment. nobody has had an issue with this since the AUTO_INCREMENT directive doesnt prevent you from doing anything except getting an error when no primary key is present (and MySQL is generally not big on complaining about constraints being violated anyway....)
SQLAlchemy is designed to create tables in such a way that it can always generate primary key values without the value being explicitly passed; however, you can always pass an explicit primary key to an insert or mapper operation and it will use that value, bypassing the AUTO_INCREMENT. for MySQL, using AUTO_INCREMENT is the only (reasonable) way you can get auto-generated PKs, which SA can then get a hold of via cursor.lastrowid. SA does use SERIAL for postgres unless an explicit Sequence or other default was specified for the column, although when rows are inserted with postgres, and the rows have no explicit PK value present, SA will explicitly call the <tablename>_id_seq sequence before each INSERT so that it has access to the newly generated primary key value (since cursor.lastrowid is somewhat "deprecated" in psycopg). On Jun 21, 2006, at 7:44 AM, Maciej Szumocki wrote: > Hello all, > > I'm wondering why the integer primary keys for MySQL are marked > as AUTO_INCREMENT by default, while they're not marked SERIAL for > Postgres for example. > > I'm referring to this fragment of code in databases\mysql.py: > > class MySQLSchemaGenerator(ansisql.ANSISchemaGenerator): > def get_column_specification(self, column, override_pk=False, > first_pk=False): > colspec = column.name + " " + column.type.engine_impl > (self.engine).get_col_spec() > default = self.get_column_default_string(column) > if default is not None: > colspec += " DEFAULT " + default > > if not column.nullable: > colspec += " NOT NULL" > if column.primary_key: > if not override_pk: > colspec += " PRIMARY KEY" > if not column.foreign_key and first_pk and isinstance > (column.type, sqltypes.Integer): > colspec += " AUTO_INCREMENT" > if column.foreign_key: > colspec += ", FOREIGN KEY (%s) REFERENCES %s(%s)" % > (column.name, column.foreign_key.column.table.name, > column.foreign_key.column.name) > return colspec > > Could someone explain the reasoning behind it to me? > > (If this is not a bug, could someone please tell me how can I > switch this behaviour off? I do not > want my primary key columns to be auto increment). > > Maciej Szumocki > > > _______________________________________________ > Sqlalchemy-users mailing list > Sqlalchemy-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users _______________________________________________ Sqlalchemy-users mailing list Sqlalchemy-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users
