Joins several values into one string, skipping NULL.
CONCAT(<value1>, <value2>, …)
CONCAT_WS(<separator>, <value1>, <value2>, …)
Converts the arguments to text and joins them one after another. Unlike the || operator, NULL doesn't “swallow” the whole result — it's simply skipped. CONCAT_WS puts a separator between the values for you.
employees
| name | department | salary | bonus | phone |
|---|---|---|---|---|
| Emma | backend | 1200 | 300 | +44 7700 900123 |
| Liam | backend | 1000 | NULL | NULL |
| Olivia | frontend | 1350 | 150 | +44 7700 900456 |
| Noah | frontend | 950 | NULL | +44 7700 900789 |
| Sophia | design | 1200 | 200 | NULL |
These tables already exist in the sandbox — the examples below use them. Want to try this in your own database? Copy the SQL.
| full_name |
|---|
| Emma Wilson |
| label |
|---|
| Emma (backend) |
| Liam (backend) |
| Olivia (frontend) |
| Noah (frontend) |
| Sophia (design) |
| name | with_pipes | with_concat |
|---|---|---|
| Emma | Emma, +44 7700 900123 | Emma, +44 7700 900123 |
| Liam | NULL | Liam, |
| Olivia | Olivia, +44 7700 900456 | Olivia, +44 7700 900456 |
| Noah | Noah, +44 7700 900789 | Noah, +44 7700 900789 |
| Sophia | NULL | Sophia, |
Liam and Sophia have no phone number: || gives NULL for the whole string, while CONCAT just skips the empty part.
CONCAT keeps a separator even where there's no value: CONCAT('Liam', ', ', NULL) gives Liam, with a trailing comma. To put separators only between existing values, use CONCAT_WS(', ', 'Liam', NULL) — you'll get just Liam.
Numbers and dates are converted to text automatically, but PostgreSQL picks how they look. If you need your own format, such as 13.09.2026, use TO_CHAR first.