GROUP_CONCAT / STRING_AGG
AggregateConcatenates values from multiple rows into a single string. GROUP_CONCAT (MySQL) or STRING_AGG (PostgreSQL).
Syntax
STRING_AGG(col, delimiter) | GROUP_CONCAT(col SEPARATOR delimiter)
Example
SELECT department,
STRING_AGG(name, ', ' ORDER BY name) as team
FROM employees
GROUP BY department;About SQL GROUP_CONCAT / STRING_AGG
The GROUP_CONCAT / STRING_AGG keyword belongs to the Aggregate category of SQL statements. Concatenates values from multiple rows into a single string. GROUP_CONCAT (MySQL) or STRING_AGG (PostgreSQL). Understanding this command is essential for any developer working with relational databases like PostgreSQL, MySQL, SQLite, or SQL Server.
SQL (Structured Query Language) is the standard language for managing and querying relational databases. The GROUP_CONCAT / STRING_AGG statement is supported across all major database systems, though specific syntax may vary slightly between PostgreSQL, MySQL, MariaDB, Oracle, SQL Server, and SQLite. Always consult your database's documentation for vendor-specific features and limitations.
Best practices for using GROUP_CONCAT / STRING_AGG: always test queries on a development database before running them in production, use parameterized queries to prevent SQL injection, and leverage EXPLAIN to understand query performance. For complex queries, consider using CTEs (Common Table Expressions) to improve readability and maintainability.