How Can I Combine Page URLs into a Single Comma-Separated String Based on User and Activity Using SQL's GROUP BY?

Aggregating Page URLs with SQL's GROUP BY

Your database table includes User, Activity, and PageURL columns. The goal is to consolidate PageURL entries for each unique User and Activity combination into a single comma-separated string.

This can be achieved using GROUP BY in conjunction with string aggregation techniques. Here's how:

<code class="language-sql">SELECT
    User,
    Activity,
    STRING_AGG(PageURL, ',') AS CombinedPageURLs
FROM
    TableName
GROUP BY
    User,
    Activity;</code>

This query directly uses the STRING_AGG function (available in many modern SQL dialects like PostgreSQL, SQL Server 2017 and later, etc.) to concatenate PageURL values within each group defined by User and Activity. The resulting comma-separated string is assigned to the CombinedPageURLs column.

Alternative for SQL Dialects Without STRING_AGG:

If your SQL database doesn't support STRING_AGG, you can use a similar approach employing FOR XML PATH:

<code class="language-sql">SELECT
    User,
    Activity,
    STUFF((
        SELECT ',' + PageURL
        FROM TableName t2
        WHERE t2.User = t1.User AND t2.Activity = t1.Activity
        FOR XML PATH('')
    ), 1, 1, '') AS CombinedPageURLs
FROM
    TableName t1
GROUP BY
    User,
    Activity;</code>

This alternative uses a subquery with FOR XML PATH('') to create the comma-separated string, and STUFF removes the leading comma. This method is compatible with older SQL Server versions. Remember to adapt table and column names to match your specific database schema. The output provides a CombinedPageURLs column containing the aggregated URLs.

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