How can I convert MS SQL T-SQL into Subsequent in MySQL - mysql

Question

Here I have a MS SQL query which I would like to convert into MySQL. I don't know how to deal with that.
WITH PartitionData as (
SELECT
TOP 10 PurchaseDate.PurchaseDate AS date,
BatchCode,
ROW_NUMBER() OVER( PARTITION BY PurchaseDate.PurchaseDate ORDER BY ( SELECT NULL ) ) AS RowNumber
FROM tblNutBatches
INNER JOIN PurchaseDate ON PurchaseDate.PurchaseDate BETWEEN tblNutBatches.Introduction_date AND tblNutBatches.expiration_date
WHERE PurchaseDate.PurchaseDate = '2004-05-01'
)
SELECT
date as date,
[1],
[2],
[3],
[4],
[5],
[6],
[7],
[8],
[9]
FROM
(
SELECT
date,
BatchCode,
RowNumber
FROM
PartitionData
)AS DataAfterFilter
PIVOT
(
MAX(BatchCode) FOR RowNumber IN ([1], [2], [3], [4], [5], [6], [7], [8], [9])
) A
OUTPUT IN SQL SERVER
Any idea would be appreciated.

Answer 1

You would typically use conditional aggregation:
SELECT date,
MAX(CASE WHEN rn = 1 THEN BatchCode end) as BatchCode1,
MAX(CASE WHEN rn = 2 THEN BatchCode end) as BatchCode2,
...
MAX(CASE WHEN rn = 10 THEN BatchCode end) as BatchCode10
FROM (
SELECT
pd.PurchaseDate AS date,
BatchCode,
ROW_NUMBER() OVER(PARTITION BY pd.PurchaseDate ORDER BY BatchCode) AS rn
FROM tblNutBatches nb
INNER JOIN PurchaseDate pd ON pd.PurchaseDate BETWEEN nb.Introduction_date AND nb.expiration_date
WHERE pd.PurchaseDate = '2004-05-01'
) t
WHERE rn <= 10
GROUP BY date
Notes:
if you want a consistent results, you need ORDER BY clauses in the subquery and in ROW_NUMBER() - I used BatchCode
do prefix BatchCode with the alias of the table it belongs to
the PARTITION BY clause of ROW_NUMBER() and the outer GROUP BY clause are not necessary strictly speaking, since the subquery is filtering on just one data anyway; I retained them, in case you need to remove the filtering at some point. Accordingly, I moved the top 10 filtering logic form the subquery to the outer query.