MySQL GROUP_CONCAT()

The MySQL GROUP_CONCAT() function is used to concatenate the values from multiple rows into a single string, grouped by a specified column. This is particularly useful when you want to aggregate data from multiple rows into a comma-separated list, for example, when you want to combine values for a particular group or category.

The basic syntax of the GROUP_CONCAT() function is as follows:

GROUP_CONCAT(expression ORDER BY column SEPARATOR separator)

• expression: The column or expression whose values you want to concatenate.
• ORDER BY column: Optional. Specifies the order in which the values should be concatenated within each group.
• separator: Optional. Defines the delimiter used to separate the concatenated values. The default separator is a comma (,).

Here’s an example of how to use the GROUP_CONCAT() function to concatenate values:

Suppose you have a table named fruits with columns category and fruit_name, and you want to concatenate the names of fruits in each category:

SELECT category, GROUP_CONCAT(fruit_name) AS concatenated_fruits
FROM fruits
GROUP BY category;

In this example, the GROUP_CONCAT() function groups the fruits by their category and concatenates the fruit_name values within each group, separated by commas.

The result might look something like this:

category  | concatenated_fruits
--------- | ----------------------
Citrus    | Orange,Lemon,Lime
Berries   | Strawberry,Blueberry,Raspberry
Tropical  | Banana,Pineapple,Mango

You can customize the separator and order of values as needed. This function is handy for creating summary lists, generating CSV-like output, or aggregating data in various ways, especially when dealing with data that’s distributed across multiple rows.