I have to compare 2 different sources and identify all the mismatches for all IDs Source_excel table Source_dw table Expected result I have tried the below query but it is giving only one mismatch. Actual output I understand that case expression will only check the first satisfying condition. Is there any other way I can check all the condition? Answer

Evaluate Multiple conditions for same row

I have to compare 2 different sources and identify all the mismatches for all IDs

Source_excel table

+-----+-------------+------+----------+
| id  | name        | City | flag     |
+-----+-------------+------+----------+
| 101 | Plate       | NY   | Ready    |
| 102 | Back washer | NY   | Sold     |
| 103 | Ring        | MC   | Planning |
| 104 | Glass       | NMC  | Ready    |
| 107 | Cover       | PR   | Ready    |
+-----+-------------+------+----------+

Source_dw table

+-----+----------+------+----------+
| id  | name     | City | flag     |
+-----+----------+------+----------+
| 101 | Plate    | NY   | Planning |
| 102 | Nut      | TN   | Expired  |
| 103 | Ring     | MC   | Planning |
| 104 | Top Wire | NY   | Ready    |
| 105 | Bolt     | MC   | Expired  |
+-----+----------+------+----------+

Expected result

+-----+-------------+----------+------------+----------+------------+---------+------------------+
| ID  | excel_name  | dw_name  | excel_flag | dw_flag  | excel_city | dw_city | RESULT           |
+-----+-------------+----------+------------+----------+------------+---------+------------------+
| 101 | Plate       | Plate    | Ready      | Planning | NY         | NY      | FLAG_MISMATCH    |
| 102 | Back washer | Nut      | Sold       | Expired  | NY         | TN      | NAME_MISMATCH    |
| 102 | Back washer | Nut      | Sold       | Expired  | NY         | TN      | FLAG_MISMATCH    |
| 102 | Back washer | Nut      | Sold       | Expired  | NY         | TN      | CITY_MISMATCH    |
| 103 | Ring        | Ring     | Planning   | Planning | MC         | MC      | ALL_MATCH        |
| 104 | Glass       | Top Wire | Ready      | Ready    | NMC        | NY      | NAME_MISMATCH    |
| 104 | Glass       | Top Wire | Ready      | Ready    | NMC        | NY      | CITY_MISMATCH    |
| 107 | Cover       |          | Ready      |          | PR         |         | MISSING IN DW    |
| 105 |             | Bolt     |            | Expired  |            | MC      | MISSING IN EXCEL |
+-----+-------------+----------+------------+----------+------------+---------+------------------+

I have tried the below query but it is giving only one mismatch.

select ISNULL(EXCEL.ID,DW.ID) ID, 
       excel.name as excel_name,dw.name as dw_name,
       excel.flag as excel_flag,dw.flag as dw_flag,
       excel.city as excel_city,dw.city as dw_city,
       RESULT = CASE WHEN excel.ID IS NULL THEN 'MISSING IN EXCEL'
                     WHEN dw.ID IS NULL THEN 'MISSING IN DW'
                     WHEN excel.NAME<>dw.NAME THEN 'NAME_MISMATCH'
                     WHEN excel.CITY<>dw.CITY THEN 'CITY_MISMATCH'
                     WHEN excel.FLAG <> dw.FLAG THEN 'FLAG_MISMATCH'
                ELSE 'ALL_MATCH' END
from source_excel excel
FULL OUTER JOIN source_dw dw ON excel.id=dw.id

Actual output

+-----+-------------+----------+------------+----------+------------+---------+------------------+
| ID  | excel_name  | dw_name  | excel_flag | dw_flag  | excel_city | dw_city | RESULT           |
+-----+-------------+----------+------------+----------+------------+---------+------------------+
| 101 | Plate       | Plate    | Ready      | Planning | NY         | NY      | FLAG_MISMATCH    |
| 102 | Back washer | Nut      | Sold       | Expired  | NY         | TN      | NAME_MISMATCH    |
| 103 | Ring        | Ring     | Planning   | Planning | MC         | MC      | ALL_MATCH        |
| 104 | Glass       | Top Wire | Ready      | Ready    | NMC        | NY      | NAME_MISMATCH    |
| 107 | Cover       |          | Ready      |          | PR         |         | MISSING IN DW    |
| 105 |             | Bolt     |            | Expired  |            | MC      | MISSING IN EXCEL |
+-----+-------------+----------+------------+----------+------------+---------+------------------+

I understand that case expression will only check the first satisfying condition. Is there any other way I can check all the condition?

Answer

If I follow you correctly, you want one row per mismatch, or one row indicating that everything matches.

You can use cross apply to generate the rows, like so:

SELECT 
    COALESCE(xl.ID, dw.ID) ID, 
    xl.name as excel_name,dw.name as dw_name,
    xl.flag as excel_flag,dw.flag as dw_flag,
    xl.city as excel_city,dw.city as dw_city,
    x.result
FROM source_excel xl
FULL OUTER JOIN source_dw dw ON xl.id = dw.id
CROSS APPLY (VALUES
    (CASE WHEN xl.ID IS NULL           THEN 'MISSING IN EXCEL' END),
    (CASE WHEN dw.ID IS NULL           THEN 'MISSING IN DW'    END),
    (CASE WHEN WHEN xl.NAME <> dw.NAME THEN 'NAME_MISMATCH'    END),
    (CASE WHEN xl.CITY <> dw.CITY      THEN 'CITY_MISMATCH'    END),
    (CASE WHEN xl.FLAG <> dw.FLAG      THEN 'FLAG_MISMATCH'    END),
    (CASE WHEN 
        xl.ID = dw.ID 
        AND xl.NAME = dw.NAME
        AND xl.CITY = dw.CITY
        AND xl.FLAG = dw.FLAG
    THEN 'ALL_MATCH' END)
) x(result)
WHERE x.result IS NOT NULL

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Answer