


How Can I Combine Multiple Actor Names into a Single Column per Movie in SQL?
Consolidating Multiple Actor Names into a Single Column per Film in SQL
Working with movie databases often requires summarizing actor information for each film. This involves merging multiple actor names associated with a single movie into a single column entry.
SQL Solution
PostgreSQL provides the string_agg()
function, ideal for this task. Here's a query demonstrating its use:
SELECT movie, string_agg(actor, ', ') AS actors FROM tbl GROUP BY movie;
This query:
-
movie
: Specifies the column holding movie titles. -
actor
: Specifies the column listing actor names. -
string_agg(actor, ', ')
: This function concatenates actor names for each movie, separating them with commas and spaces. -
GROUP BY movie
: Groups the results, ensuring one row per movie.
Detailed Explanation
The string_agg()
function excels at combining multiple rows into a single string value. Here, it creates a comma-separated list of actors for each film.
For sorted actor lists, include an ORDER BY
clause within string_agg()
:
string_agg(actor, ', ' ORDER BY actor) AS actors
However, a subquery often offers better performance for sorting.
Advantages of string_agg()
- Streamlines data processing by aggregating multiple rows into single values.
- Improves data presentation by grouping related actor data for each movie.
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