Compare Schema Between Tables

In the process of purging data to history tables,
we wanted to make sure that no schema changes have been done
to the main or the history table.
So to ensure identical schemas, we use this function:


ALTER FUNCTION dbo.fnCompareTableSchema
(
@t1Name NVARCHAR(257)
,@t2Name NVARCHAR(257)
)
RETURNS BIT
AS
/*
Compares the schema of 2 tables
If the schema is different RETURNS 0
If the schema is identical between the two table, RETURNS 1
NOTE: system tables or non-existant tables that are NOT in INFORMATION_SCHEMA views will compare equal (RETURNS 1)
==================================================================================================================
SAMPLE USAGE:
DECLARE @schemaOK BIT
SELECT @schemaOK = dbo.fnCompareTableSchema('dbo.table1','dbo.table2')

IF @schemaOK = 1
PRINT 'TABLE SCHEMA IDENTICAL'
ELSE
PRINT 'TABLE SCHEMA DIFFERENT'
==================================================================================================================
*/
BEGIN
IF @t1Name = @t2Name
RETURN 1

-- check if schema is different
IF EXISTS
(
SELECT*
FROM
(
SELECTCOLUMN_NAME, ORDINAL_POSITION, DATA_TYPE
, COLUMN_DEFAULT, IS_NULLABLE
, CHARACTER_MAXIMUM_LENGTH, NUMERIC_PRECISION, NUMERIC_SCALE
, COLLATION_NAME
FROMINFORMATION_SCHEMA.COLUMNS
WHERETABLE_SCHEMA = COALESCE(PARSENAME(@t1Name,2),'dbo') AND TABLE_NAME = PARSENAME(@t1Name,1)
UNION ALL
SELECTCOLUMN_NAME, ORDINAL_POSITION, DATA_TYPE
, COLUMN_DEFAULT, IS_NULLABLE
, CHARACTER_MAXIMUM_LENGTH, NUMERIC_PRECISION, NUMERIC_SCALE
, COLLATION_NAME
FROMINFORMATION_SCHEMA.COLUMNS
WHERETABLE_SCHEMA = COALESCE(PARSENAME(@t2Name,2),'dbo') AND TABLE_NAME = PARSENAME(@t2Name,1)
) U
GROUP BY
COLUMN_NAME, ORDINAL_POSITION, DATA_TYPE
HAVING COUNT(*) <> 2
)
RETURN 0

-- schema identical
RETURN 1
END