How to Simulate ROW_NUMBER() Functionality in Microsoft Access?
Jan 02, 2025 pm 01:12 PMAchieving Row Number Functionality in MS Access
The "ROW_NUMBER OVER (PARTITION BY)" function, commonly used in SQL to assign sequential numbers within partitions of a result set, can be emulated in Microsoft Access using self-joins and aggregation.
Consider the following data set:
DOC_TYPE Ino 3a 1800xxc1 3b 1810xxc2 3c 1700xxc3 3a 1700xxc4 3a 1800xxc5 3a 1800xxc6 3b 1800xxc7
To replicate the "ROW_NUMBER" behavior, we can use a query like this:
SELECT t1.DOC_TYPE, t1.Ino, COUNT(*) AS RowNum FROM YourTable AS t1 INNER JOIN YourTable AS t2 ON t2.DOC_TYPE = t1.DOC_TYPE AND t2.Ino <= t1.Ino GROUP BY t1.DOC_TYPE, t1.Ino ORDER BY 1, 3
This query self-joins the table on the DOC_TYPE column and a less-than-or-equal comparison of the Ino values. It then aggregates the rows by DOC_TYPE and Ino, counting the occurrences of each unique DOC_TYPE, Ino pair. The resulting count, assigned to the RowNum alias, represents the sequential row number.
Applying this query to the sample data will produce the following result:
DOC_TYPE Ino RowNum 3a 1800xxc1 1 3a 1700xxc4 2 3a 1800xxc5 3 3a 1800xxc6 4 3b 1810xxc2 1 3b 1800xxc7 2 3c 1700xxc3 1
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