How to Concatenate Strings in MySQL Using GROUP BY?

Using GROUP BY connection string in MySQL

In database management systems, it is often necessary to merge multiple strings into a single string. In MySQL, you can use the GROUP BY function to achieve this functionality.

The syntax for MySQL string concatenation is as follows:

<code class="language-sql">SELECT id, GROUP_CONCAT(name SEPARATOR ' ') FROM table GROUP BY id;</code>

This query will group the rows by the id column and concatenate the values ​​in the name column using the specified separator (space in this case).

Example

Consider the following form:

foo_id	foo_name
1	A
1	B
2	C

To concatenate the foo_id values ​​for each foo_name you can execute the following query:

<code class="language-sql">SELECT foo_id, GROUP_CONCAT(foo_name SEPARATOR ' ') FROM foo GROUP BY foo_id;</code>

This query will return the following results:

foo_id	foo_name
1	A B
2	C

As you can see, each foo_id value of foo_name has been concatenated into a single string.

Additional information

• GROUP_CONCAT Functions can concatenate any data type, not just strings.
• You can specify multiple columns in the GROUP BY clause.
• You can also specify the order in which values ​​are concatenated.

For more information about the GROUP_CONCAT function, see the MySQL documentation: https://www.php.cn/link/18fc3b6cc1e55ccea877c161e2e9ba27

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