How Can I Concatenate Strings in MySQL Using GROUP BY?

Combining Duplicate Entries in MySQL Using GROUP_CONCAT

This guide explains how to merge rows with identical foo_id values, concatenating their corresponding foo_name entries into a single string within a MySQL table.

The Solution: GROUP_CONCAT and GROUP BY

MySQL's GROUP_CONCAT function, used in conjunction with GROUP BY, efficiently solves this problem. Here's the query:

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

Query Breakdown:

• SELECT id, GROUP_CONCAT(name SEPARATOR ' '): This selects the id column and uses GROUP_CONCAT to combine the name column values for each group. The SEPARATOR ' ' specifies a space as the delimiter between concatenated names.
• FROM table: Indicates the table containing the data.
• GROUP BY id: Groups the rows based on the unique values in the id column.

How it Works:

GROUP_CONCAT aggregates non-NULL values from each group defined by GROUP BY. The separator ensures readability by placing spaces between the concatenated names. This effectively merges rows with the same id, creating a single row with all associated names combined into one string.

Further Reading:

For more comprehensive information on GROUP_CONCAT, consult the official MySQL documentation: https://www.php.cn/link/18fc3b6cc1e55ccea877c161e2e9ba27

The above is the detailed content of How Can I Concatenate Strings in MySQL Using GROUP BY?. For more information, please follow other related articles on the PHP Chinese website!