By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
CREATE TABLE existing (phone VARCHAR(255))
SELECT '123456789' phone UNION ALL
SELECT '789456123' UNION ALL
SELECT '456456456' UNION ALL
SELECT '654654645' UNION ALL
SELECT '123321123' ;
SELECT * FROM existing;
| phone |
|---|
| 123456789 |
| 789456123 |
| 456456456 |
| 654654645 |
| 123321123 |
CREATE TABLE new (phone VARCHAR(255) UNIQUE)
SELECT '123456789' phone UNION ALL
SELECT '464646464' UNION ALL
SELECT '123321123' ;
SELECT * FROM new;
| phone |
|---|
| 123321123 |
| 123456789 |
| 464646464 |
INSERT
INTO existing (phone)
SELECT phone
FROM new
WHERE NOT EXISTS ( SELECT NULL
FROM existing
WHERE new.phone = existing.phone );
SELECT * FROM existing;
| phone |
|---|
| 123456789 |
| 789456123 |
| 456456456 |
| 654654645 |
| 123321123 |
| 464646464 |