apps/south/db/mysql.py

   1
   2 from django.db import connection
   3 from django.conf import settings
   4 from south.db import generic
   5
   6 class DatabaseOperations(generic.DatabaseOperations):
   7
   8     """
   9     MySQL implementation of database operations.
  10     """
  11
  12     alter_string_set_type = ''
  13     alter_string_set_null = 'MODIFY %(column)s %(type)s NULL;'
  14     alter_string_drop_null = 'MODIFY %(column)s %(type)s NOT NULL;'
  15     drop_index_string = 'DROP INDEX %(index_name)s ON %(table_name)s'
  16     allows_combined_alters = False
  17     has_ddl_transactions = False
  18
  19     def execute(self, sql, params=[]):
  20         if hasattr(settings, "DATABASE_STORAGE_ENGINE") and \
  21            settings.DATABASE_STORAGE_ENGINE:
  22             generic.DatabaseOperations.execute(self, "SET storage_engine=%s;" %
  23                 settings.DATABASE_STORAGE_ENGINE)
  24         return generic.DatabaseOperations.execute(self, sql, params)
  25     execute.__doc__ = generic.DatabaseOperations.execute.__doc__
  26
  27     def rename_column(self, table_name, old, new):
  28         if old == new or self.dry_run:
  29             return []
  30
  31         qn = connection.ops.quote_name
  32
  33         rows = [x for x in self.execute('DESCRIBE %s' % (qn(table_name),)) if x[0] == old]
  34
  35         if not rows:
  36             raise ValueError("No column '%s' in '%s'." % (old, table_name))
  37
  38         params = (
  39             qn(table_name),
  40             qn(old),
  41             qn(new),
  42             rows[0][1],
  43             rows[0][2] == "YES" and "NULL" or "NOT NULL",
  44             rows[0][3] == "PRI" and "PRIMARY KEY" or "",
  45             rows[0][4] and "DEFAULT " or "",
  46             rows[0][4] and "%s" or "",
  47             rows[0][5] or "",
  48         )
  49
  50         sql = 'ALTER TABLE %s CHANGE COLUMN %s %s %s %s %s %s %s %s;' % params
  51
  52         if rows[0][4]:
  53             self.execute(sql, (rows[0][4],))
  54         else:
  55             self.execute(sql)
  56
  57
  58     def rename_table(self, old_table_name, table_name):
  59         """
  60         Renames the table 'old_table_name' to 'table_name'.
  61         """
  62         if old_table_name == table_name:
  63             # No Operation
  64             return
  65         qn = connection.ops.quote_name
  66         params = (qn(old_table_name), qn(table_name))
  67         self.execute('RENAME TABLE %s TO %s;' % params)