How can I concatenate multiple rows into a single string in SQL?

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If you are dealing with a large database, there might be a situation where you need to combine data from multiple rows into a single string. Fortunately, SQL (Structured Query Language) offers some simple tools and methods for this consolidation. In the following sections, we’ll look into how to concatenate multiple rows into a single string in SQL. Let’s dive in!

Why is Concatenation Important?

Concatenation, or the process of combining strings, is a common task when managing and analyzing data. It helps create more readable results and aids in optimizing storage. SQL offers the CONCAT function, but what if you want to CONCAT data from multiple rows, not just two strings? There are a few different methods you can use depending on your DBMS – let’s go over them.

Concatenating Rows into a String in SQL Server

In SQL Server, you can use the FOR XML PATH method to concatenate rows into a single string. Let’s say you have a Products table, and you want to concatenate all products into one string.

In the code above, COALESCE is used to handle NULL values. CONCAT_WS (Concatenate With Separator) can also be used in SQL Server 2017 (14.x) and later versions:

Concatenating Rows into a String in MySQL

The MySQL equivalent of SQL Server’s STRING_AGG function would be the GROUP_CONCAT function:

Concatenating Rows into a String in Oracle SQL

Oracle concatenation is performed using the aggregation function LISTAGG:

Conclusion

In conclusion, SQL provides numerous ways to concatenate multiple rows into one string. The key is understanding your DBMS and implementing the technique that suits it best.