Combining Actor Names for Each Movie in a SQL Table
Imagine a table with "Movie" and "Actor" columns. The task is to retrieve a list of movies and their corresponding actors, with all actors for each movie combined into a single string.
Solution using string_agg()
:
The most efficient method uses the string_agg()
function (available in PostgreSQL 9.0 and later):
SELECT movie, string_agg(actor, ', ') AS actor_list FROM table_name GROUP BY movie;
string_agg()
concatenates actor names, separated by commas, for each movie. GROUP BY movie
ensures one row per film.
Alternative for Older PostgreSQL Versions (pre-9.0):
For older PostgreSQL versions, use array_agg()
and array_to_string()
:
SELECT movie, array_to_string(array_agg(actor ORDER BY actor), ', ') AS actor_list FROM table_name GROUP BY movie;
This aggregates actors into an array, then converts it to a comma-separated string. The ORDER BY actor
clause sorts actors alphabetically within each movie's list.
Customizing the Actor List Order:
To control the order of actors within each list (e.g., by billing order), add ORDER BY
inside string_agg()
or array_agg()
:
SELECT movie, string_agg(actor, ', ' ORDER BY actor) AS actor_list --Alphabetical order FROM table_name GROUP BY movie;
This approach streamlines the presentation of movie-actor relationships, facilitating data analysis and display.
The above is the detailed content of How to Concatenate Actors for Each Movie in a SQL Table?. For more information, please follow other related articles on the PHP Chinese website!

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