How Can I Use MySQL's DISTINCT Keyword with GROUP_CONCAT() to Get Unique Concatenated Strings?

MySQL DISTINCT with GROUP_CONCAT()

In MySQL, the GROUP_CONCAT() function can be used to combine values from multiple rows into a single concatenated string. However, if duplicate values exist in the column being concatenated, they will appear multiple times in the resulting string.

Suppose we have a table with a "categories" column, where each row contains one or more category strings. To retrieve a concatenated string of unique category values for each row, we can use the following query:

SELECT GROUP_CONCAT(DISTINCT categories ORDER BY categories ASC SEPARATOR ' ') FROM table

This query utilizes the DISTINCT keyword with the GROUP_CONCAT() function to eliminate duplicate values before concatenation. The ORDER BY clause sorts the values in ascending order before concatenating, ensuring that the order of values remains consistent across rows.

With the DISTINCT attribute, the GROUP_CONCAT() function will effectively remove any duplicate values and return a single, comma-separated string containing all unique categories for each row. This provides a more concise and accurate representation of the data, making it easier to analyze and interpret.

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