Compare data of two tables

/****** Object: StoredProcedure [dbo].[usp_CompareTable] Script Date: 08-30-2019 00:59:18 ******/-- =======================================================================================================================================================
-- Purpose : This stored procedure will compare data of two tables.
-- No. of Parameter : 6
-- @db1 : First Database Name
-- @Tb1 : Table Name of First Database
-- @db2 : Second Database Name
-- @Tb2 : Table Name of Second Database
-- @Matching Key: Matching Keys
-- @TopN : No. of records you want to display after comparision
-- =======================================================================================================================================================
SET ANSI_NULLS ON;
GO

SET QUOTED_IDENTIFIER ON;
GO

SET ANSI_WARNINGS OFF;
GO

ALTER PROCEDURE dbo.usp_CompareTable
(   @Db1         VARCHAR(100),
    @Tb1         VARCHAR(100),
    @Db2         VARCHAR(100),
    @Tb2         VARCHAR(100),
    @MatchingKey VARCHAR(500),
    @TopN        INT = NULL)
AS
BEGIN
    DECLARE @JoinCondition VARCHAR(MAX) = '';
    DECLARE @i INT = 0;
    DECLARE @as VARCHAR(200);
    SELECT
          value,
          rnm = ROW_NUMBER() OVER (ORDER BY value)
     INTO #ColumnList
     FROM STRING_SPLIT(@MatchingKey, ',');
    SELECT @i = COUNT(1) FROM #ColumnList;
    WHILE @i > 0
    BEGIN

        --Prepare JOIN condition
        SELECT
               @JoinCondition
            = @JoinCondition + ' A' + '.' + value + '=' + ' B' + '.' + value
         FROM  #ColumnList
         WHERE rnm = @i;
        SET @i = @i - 1;
        IF @i <> 0
            SET @JoinCondition = @JoinCondition + ' AND ';
    END;

    --Prepare CASE condition
    DECLARE @CaseCondition VARCHAR(MAX);
    CREATE TABLE #cases
    (CaseFromSelect VARCHAR(MAX));
    INSERT INTO
        #cases
    EXEC ('SELECT ''CASE WHEN A.''+A.COLUMN_NAME+'' <> B.''+B.COLUMN_NAME+'' THEN ''''''+A.COLUMN_NAME+

''''''''+'' ELSE '''''''' END '' +A.COLUMN_NAME

FROM ' + @Db1 + '.INFORMATION_SCHEMA.COLUMNS A INNER JOIN ' + @Db2 + '.INFORMATION_SCHEMA.COLUMNS B

ON A.COLUMN_NAME=B.COLUMN_NAME WHERE A.Table_name =''' + @Tb1 + ''' and A.Table_catalog=''' + @Db1 + ''' AND B.table_name =''' + @Tb2 + ''' AND B.Table_catalog=''' + @Db2 + '''');
    SET @CaseCondition = '';
    SELECT @CaseCondition = @CaseCondition + CaseFromSelect + ', ' FROM #cases;
    SELECT @CaseCondition = SUBSTRING(@CaseCondition, 0, LEN(@CaseCondition));
    EXEC ('SELECT ' + @CaseCondition + ' INTO ##T123 FROM ' + @Db1 + '..' + @Tb1 + ' A ' + ' INNER JOIN ' + @Db2 + '..' + @Tb2 + ' B ' + ' ON ' + @JoinCondition);
    CREATE TABLE #Mismatchingcolumns
    (Columnlist VARCHAR(5000));
    DECLARE @s VARCHAR(MAX) = '';
    SELECT @s = @s + 'SELECT ' + COLUMN_NAME + ' FROM ##t123 UNION '
     FROM  tempdb.INFORMATION_SCHEMA.COLUMNS
     WHERE TABLE_NAME = '##T123';
    SELECT @s = SUBSTRING(@s, 1, LEN(@s) - 6);
    INSERT INTO #Mismatchingcolumns EXEC (@s);
    UPDATE #Mismatchingcolumns
     SET   Columnlist = ' A ' + '.' + Columnlist + ' , ' + ' B ' + '.' + Columnlist
     WHERE Columnlist <> '';
    DECLARE @Clist VARCHAR(MAX) = '';
    SELECT @Clist = @Clist + (Columnlist) + ', '
     FROM  #Mismatchingcolumns
     WHERE Columnlist <> '';
    SELECT @Clist = SUBSTRING(@Clist, 0, LEN(@Clist));
    IF
    (
        SELECT COUNT(*) FROM #Mismatchingcolumns WHERE Columnlist <> ''
    ) = 0
        SELECT 'All data identical';
    ELSE
    BEGIN
        IF @TopN IS NULL
            SET @TopN = 999999999;
        DECLARE @FinalQuery VARCHAR(MAX) = '';
        SET @FinalQuery
            = 'SELECT TOP ' + CAST(@TopN AS VARCHAR(10)) + ' ' + @Clist + ' FROM ' + @Db1
              + '..' + @Tb1 + ' A ' + ' INNER JOIN ' + @Db2 + '..' + @Tb2 + ' B '
              + ' ON ' + @JoinCondition;
        EXEC (@FinalQuery);
    END;
    DROP TABLE ##T123;
    DROP TABLE #Mismatchingcolumns;
END;