Basic String Aggregation

basic

Create comma-separated list of employees per department

SELECT

department,

STRING_AGG(employee_name, ', ') AS employees

FROM employees

GROUP BY department;

department | employees

Engineering | Alice, Bob, Carol

Sales | Dave, Eve

Marketing | Frank

STRING_AGG concatenates employee names with comma separator. One row per department.

PostgreSQL

Ordered String Aggregation

intermediate

List products per category, alphabetically ordered

SELECT

category,

STRING_AGG(product_name, ', ' ORDER BY product_name) AS products

FROM products

GROUP BY category

ORDER BY category;

category | products

Electronics | Keyboard, Laptop, Mouse

Furniture | Chair, Desk, Table

ORDER BY inside STRING_AGG sorts values before concatenation. Results alphabetically ordered.

PostgreSQL

Product Tags Collection

intermediate

Aggregate all tags for each product

SELECT

product_id,

product_name,

STRING_AGG(tag_name, ', ' ORDER BY tag_name) AS tags

FROM products p

JOIN product_tags pt ON p.product_id = pt.product_id

GROUP BY product_id, product_name;

product_id | product_name | tags

1 | Laptop | electronics, portable, wireless