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from sqlalchemy.ext.compiler import compiles
from .. import util
from .impl import DefaultImpl
from .base import alter_table, AddColumn, ColumnName, RenameTable,\
format_table_name, format_column_name, ColumnNullable, alter_column,\
format_server_default, ColumnDefault, format_type, ColumnType
from sqlalchemy.sql.expression import ClauseElement, Executable
class MSSQLImpl(DefaultImpl):
__dialect__ = 'mssql'
transactional_ddl = True
batch_separator = "GO"
def __init__(self, *arg, **kw):
super(MSSQLImpl, self).__init__(*arg, **kw)
self.batch_separator = self.context_opts.get(
"mssql_batch_separator",
self.batch_separator)
def _exec(self, construct, *args, **kw):
result = super(MSSQLImpl, self)._exec(construct, *args, **kw)
if self.as_sql and self.batch_separator:
self.static_output(self.batch_separator)
return result
def emit_begin(self):
self.static_output("BEGIN TRANSACTION" + self.command_terminator)
def emit_commit(self):
super(MSSQLImpl, self).emit_commit()
if self.as_sql and self.batch_separator:
self.static_output(self.batch_separator)
def alter_column(self, table_name, column_name,
nullable=None,
server_default=False,
name=None,
type_=None,
schema=None,
existing_type=None,
existing_server_default=None,
existing_nullable=None,
**kw
):
if nullable is not None and existing_type is None:
if type_ is not None:
existing_type = type_
# the NULL/NOT NULL alter will handle
# the type alteration
type_ = None
else:
raise util.CommandError(
"MS-SQL ALTER COLUMN operations "
"with NULL or NOT NULL require the "
"existing_type or a new type_ be passed.")
super(MSSQLImpl, self).alter_column(
table_name, column_name,
nullable=nullable,
type_=type_,
schema=schema,
existing_type=existing_type,
existing_nullable=existing_nullable,
**kw
)
if server_default is not False:
if existing_server_default is not False or \
server_default is None:
self._exec(
_ExecDropConstraint(
table_name, column_name,
'sys.default_constraints')
)
if server_default is not None:
super(MSSQLImpl, self).alter_column(
table_name, column_name,
schema=schema,
server_default=server_default)
if name is not None:
super(MSSQLImpl, self).alter_column(
table_name, column_name,
schema=schema,
name=name)
def bulk_insert(self, table, rows, **kw):
if self.as_sql:
self._exec(
"SET IDENTITY_INSERT %s ON" %
self.dialect.identifier_preparer.format_table(table)
)
super(MSSQLImpl, self).bulk_insert(table, rows, **kw)
self._exec(
"SET IDENTITY_INSERT %s OFF" %
self.dialect.identifier_preparer.format_table(table)
)
else:
super(MSSQLImpl, self).bulk_insert(table, rows, **kw)
def drop_column(self, table_name, column, **kw):
drop_default = kw.pop('mssql_drop_default', False)
if drop_default:
self._exec(
_ExecDropConstraint(
table_name, column,
'sys.default_constraints')
)
drop_check = kw.pop('mssql_drop_check', False)
if drop_check:
self._exec(
_ExecDropConstraint(
table_name, column,
'sys.check_constraints')
)
drop_fks = kw.pop('mssql_drop_foreign_key', False)
if drop_fks:
self._exec(
_ExecDropFKConstraint(table_name, column)
)
super(MSSQLImpl, self).drop_column(table_name, column, **kw)
class _ExecDropConstraint(Executable, ClauseElement):
def __init__(self, tname, colname, type_):
self.tname = tname
self.colname = colname
self.type_ = type_
class _ExecDropFKConstraint(Executable, ClauseElement):
def __init__(self, tname, colname):
self.tname = tname
self.colname = colname
@compiles(_ExecDropConstraint, 'mssql')
def _exec_drop_col_constraint(element, compiler, **kw):
tname, colname, type_ = element.tname, element.colname, element.type_
# from http://www.mssqltips.com/sqlservertip/1425/\
# working-with-default-constraints-in-sql-server/
# TODO: needs table formatting, etc.
return """declare @const_name varchar(256)
select @const_name = [name] from %(type)s
where parent_object_id = object_id('%(tname)s')
and col_name(parent_object_id, parent_column_id) = '%(colname)s'
exec('alter table %(tname_quoted)s drop constraint ' + @const_name)""" % {
'type': type_,
'tname': tname,
'colname': colname,
'tname_quoted': format_table_name(compiler, tname, None),
}
@compiles(_ExecDropFKConstraint, 'mssql')
def _exec_drop_col_fk_constraint(element, compiler, **kw):
tname, colname = element.tname, element.colname
return """declare @const_name varchar(256)
select @const_name = [name] from
sys.foreign_keys fk join sys.foreign_key_columns fkc
on fk.object_id=fkc.constraint_object_id
where fkc.parent_object_id = object_id('%(tname)s')
and col_name(fkc.parent_object_id, fkc.parent_column_id) = '%(colname)s'
exec('alter table %(tname_quoted)s drop constraint ' + @const_name)""" % {
'tname': tname,
'colname': colname,
'tname_quoted': format_table_name(compiler, tname, None),
}
@compiles(AddColumn, 'mssql')
def visit_add_column(element, compiler, **kw):
return "%s %s" % (
alter_table(compiler, element.table_name, element.schema),
mssql_add_column(compiler, element.column, **kw)
)
def mssql_add_column(compiler, column, **kw):
return "ADD %s" % compiler.get_column_specification(column, **kw)
@compiles(ColumnNullable, 'mssql')
def visit_column_nullable(element, compiler, **kw):
return "%s %s %s %s" % (
alter_table(compiler, element.table_name, element.schema),
alter_column(compiler, element.column_name),
format_type(compiler, element.existing_type),
"NULL" if element.nullable else "NOT NULL"
)
@compiles(ColumnDefault, 'mssql')
def visit_column_default(element, compiler, **kw):
# TODO: there can also be a named constraint
# with ADD CONSTRAINT here
return "%s ADD DEFAULT %s FOR %s" % (
alter_table(compiler, element.table_name, element.schema),
format_server_default(compiler, element.default),
format_column_name(compiler, element.column_name)
)
@compiles(ColumnName, 'mssql')
def visit_rename_column(element, compiler, **kw):
return "EXEC sp_rename '%s.%s', %s, 'COLUMN'" % (
format_table_name(compiler, element.table_name, element.schema),
format_column_name(compiler, element.column_name),
format_column_name(compiler, element.newname)
)
@compiles(ColumnType, 'mssql')
def visit_column_type(element, compiler, **kw):
return "%s %s %s" % (
alter_table(compiler, element.table_name, element.schema),
alter_column(compiler, element.column_name),
format_type(compiler, element.type_)
)
@compiles(RenameTable, 'mssql')
def visit_rename_table(element, compiler, **kw):
return "EXEC sp_rename '%s', %s" % (
format_table_name(compiler, element.table_name, element.schema),
format_table_name(compiler, element.new_table_name, element.schema)
)
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