How to Count Items in a Comma-Separated SQL Column?

Counting Items in a Comma-Separated List with SQL

Counting the number of items in a comma-separated list stored in a SQL column can be achieved using a simple technique that combines string manipulation and math operations.

The key to this approach lies in subtracting the length of the original string from the length of the same string without any commas. By removing the commas, the difference in length represents the number of comma-separators, which corresponds to the number of items in the list.

Here's a practical example:

SELECT LENGTH(fooCommaDelimColumn) - LENGTH(REPLACE(fooCommaDelimColumn, ',', '')) AS listCount
FROM table
WHERE>

In this query, fooCommaDelimColumn is the name of the column containing the comma-separated list. By subtracting the length of the list without commas from the original length, we obtain the number of items in the list.

It's important to note that if the comma-separated list has a trailing comma (e.g., cats,dogs,cows,), the result will be one less than the actual number of items. In such cases, adding 1 to the expression would provide the correct count.

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