Takes the given number of characters from the start of a string.
LEFT(<text>, <count>)
A shorter way to write the most common SUBSTRING: LEFT(name, 1) is the first letter. A negative count means “everything except”: LEFT(<text>, -4) drops the last four characters. Its mirror function is RIGHT, which takes characters from the end.
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.
| first_four |
|---|
| Post |
| department | short_code |
|---|---|
| backend | bac |
| design | des |
| frontend | fro |
| without_extension |
|---|
| report |
A negative count isn't an error — it means “everything except”. That hides a subtle bug: for an email without @, LEFT(email, POSITION('@' IN email) - 1) becomes LEFT(email, -1) — everything except the last character.
A count larger than the length isn't an error either: LEFT('SQL', 10) simply returns SQL.