SQLite GROUP_CONCAT

Summary: in this tutorial, you will learn how to use the SQLite GROUP_CONCAT() function to concatenate non-null values in a column.

Introduction to SQLite GROUP_CONCAT() function

The GROUP_CONCAT() function is an aggregate function that concatenates all non-null values in a column.

The following shows the syntax of the GROUP_CONCAT() function:

GROUP_CONCAT(expression [,separator])

In this syntax:

•  expression is a column or an expression that will be used for concatenation.
• separator: all values will be separated by the separator. If you skip the separator, the GROUP_CONCAT() function uses a comma (“,”) by default.

SQLite GROUP_CONCAT() function demonstration

First, create a new table named t for the demonstration:

CREATE TABLE t(
    id INTEGER PRIMARY KEY,
    val TEXT
);

Second, insert three strings into the t table

INSERT INTO t(val)
VALUES('A'),('B'),(NULL),('C');

Third, query data from the t table:

SELECT 
    id,
    val
FROM
    t;

Here is the output:

Fourth, the following statement uses the GROUP_CONCAT() function to concatenate all values in the  val column of the t table:

SELECT
    GROUP_CONCAT(val)
FROM
    t;

In this example, we did not use the separator, therefore, the GROUP_CONCAT() function uses a comma by default.

The following picture shows the output:

Fifth, if you don’t want to use a comma as the separator, you can use another string, for example, a semicolon (“;”):

SELECT
    GROUP_CONCAT(val,';')
FROM
    t;

SQLite GROUP_CONCAT() function example

The following statement gets the album id and a list of comma-separated track names for each album:

SELECT
    Title,
    GROUP_CONCAT(name,';') track_list
FROM
    tracks t
INNER JOIN albums a on a.AlbumId = t.AlbumId
GROUP BY
    Title
ORDER BY
    Title;

The output is shown as follows:

In this example:

• First, the GROUP BY clause divides the tracks by album into groups.
• Then, the GROUP_CONCAT() function applies to each group to concatenate track names.

In this tutorial, you have learned how to use the SQLite GROUP_CONCAT() function to concatenates all non-null values in a column.