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[EDIT] FILE: information_schema.py

# mssql/information_schema.py
# Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php

# TODO: should be using the sys. catalog with SQL Server, not information
# schema

from ... import cast
from ... import Column
from ... import MetaData
from ... import Table
from ... import util
from ...ext.compiler import compiles
from ...sql import expression
from ...types import Boolean
from ...types import Integer
from ...types import String
from ...types import TypeDecorator
from ...types import Unicode

ischema = MetaData()

class CoerceUnicode(TypeDecorator):
    impl = Unicode

def process_bind_param(self, value, dialect):
        if util.py2k and isinstance(value, util.binary_type):
            value = value.decode(dialect.encoding)
        return value

def bind_expression(self, bindvalue):
        return _cast_on_2005(bindvalue)

class _cast_on_2005(expression.ColumnElement):
    def __init__(self, bindvalue):
        self.bindvalue = bindvalue

@compiles(_cast_on_2005)
def _compile(element, compiler, **kw):
    from . import base

if (
        compiler.dialect.server_version_info is None
        or compiler.dialect.server_version_info < base.MS_2005_VERSION
    ):
        return compiler.process(element.bindvalue, **kw)
    else:
        return compiler.process(cast(element.bindvalue, Unicode), **kw)

schemata = Table(
    "SCHEMATA",
    ischema,
    Column("CATALOG_NAME", CoerceUnicode, key="catalog_name"),
    Column("SCHEMA_NAME", CoerceUnicode, key="schema_name"),
    Column("SCHEMA_OWNER", CoerceUnicode, key="schema_owner"),
    schema="INFORMATION_SCHEMA",
)

tables = Table(
    "TABLES",
    ischema,
    Column("TABLE_CATALOG", CoerceUnicode, key="table_catalog"),
    Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
    Column("TABLE_NAME", CoerceUnicode, key="table_name"),
    Column("TABLE_TYPE", CoerceUnicode, key="table_type"),
    schema="INFORMATION_SCHEMA",
)

columns = Table(
    "COLUMNS",
    ischema,
    Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
    Column("TABLE_NAME", CoerceUnicode, key="table_name"),
    Column("COLUMN_NAME", CoerceUnicode, key="column_name"),
    Column("IS_NULLABLE", Integer, key="is_nullable"),
    Column("DATA_TYPE", String, key="data_type"),
    Column("ORDINAL_POSITION", Integer, key="ordinal_position"),
    Column(
        "CHARACTER_MAXIMUM_LENGTH", Integer, key="character_maximum_length"
    ),
    Column("NUMERIC_PRECISION", Integer, key="numeric_precision"),
    Column("NUMERIC_SCALE", Integer, key="numeric_scale"),
    Column("COLUMN_DEFAULT", Integer, key="column_default"),
    Column("COLLATION_NAME", String, key="collation_name"),
    schema="INFORMATION_SCHEMA",
)

constraints = Table(
    "TABLE_CONSTRAINTS",
    ischema,
    Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
    Column("TABLE_NAME", CoerceUnicode, key="table_name"),
    Column("CONSTRAINT_NAME", CoerceUnicode, key="constraint_name"),
    Column("CONSTRAINT_TYPE", CoerceUnicode, key="constraint_type"),
    schema="INFORMATION_SCHEMA",
)

column_constraints = Table(
    "CONSTRAINT_COLUMN_USAGE",
    ischema,
    Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
    Column("TABLE_NAME", CoerceUnicode, key="table_name"),
    Column("COLUMN_NAME", CoerceUnicode, key="column_name"),
    Column("CONSTRAINT_NAME", CoerceUnicode, key="constraint_name"),
    schema="INFORMATION_SCHEMA",
)

key_constraints = Table(
    "KEY_COLUMN_USAGE",
    ischema,
    Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
    Column("TABLE_NAME", CoerceUnicode, key="table_name"),
    Column("COLUMN_NAME", CoerceUnicode, key="column_name"),
    Column("CONSTRAINT_NAME", CoerceUnicode, key="constraint_name"),
    Column("CONSTRAINT_SCHEMA", CoerceUnicode, key="constraint_schema"),
    Column("ORDINAL_POSITION", Integer, key="ordinal_position"),
    schema="INFORMATION_SCHEMA",
)

ref_constraints = Table(
    "REFERENTIAL_CONSTRAINTS",
    ischema,
    Column("CONSTRAINT_CATALOG", CoerceUnicode, key="constraint_catalog"),
    Column("CONSTRAINT_SCHEMA", CoerceUnicode, key="constraint_schema"),
    Column("CONSTRAINT_NAME", CoerceUnicode, key="constraint_name"),
    # TODO: is CATLOG misspelled ?
    Column(
        "UNIQUE_CONSTRAINT_CATLOG",
        CoerceUnicode,
        key="unique_constraint_catalog",
    ),
    Column(
        "UNIQUE_CONSTRAINT_SCHEMA",
        CoerceUnicode,
        key="unique_constraint_schema",
    ),
    Column(
        "UNIQUE_CONSTRAINT_NAME", CoerceUnicode, key="unique_constraint_name"
    ),
    Column("MATCH_OPTION", String, key="match_option"),
    Column("UPDATE_RULE", String, key="update_rule"),
    Column("DELETE_RULE", String, key="delete_rule"),
    schema="INFORMATION_SCHEMA",
)

views = Table(
    "VIEWS",
    ischema,
    Column("TABLE_CATALOG", CoerceUnicode, key="table_catalog"),
    Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
    Column("TABLE_NAME", CoerceUnicode, key="table_name"),
    Column("VIEW_DEFINITION", CoerceUnicode, key="view_definition"),
    Column("CHECK_OPTION", String, key="check_option"),
    Column("IS_UPDATABLE", String, key="is_updatable"),
    schema="INFORMATION_SCHEMA",
)

computed_columns = Table(
    "computed_columns",
    ischema,
    Column("object_id", Integer),
    Column("name", CoerceUnicode),
    Column("is_computed", Boolean),
    Column("is_persisted", Boolean),
    Column("definition", CoerceUnicode),
    schema="sys",
)

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