how to select multiple items using the AND operator Here is my employe table

mysql&gt; select * from employe;
+------+------+------------+---------------------+------+------+------+
| ENO  | ENOM | PROF       | DATAEMB             | SALL | COMM | DNO  |
+------+------+------------+---------------------+------+------+------+
|   10 | Joe  | Ingenieur  | 2020-03-06 18:24:46 | 4000 | 3000 |    3 |
|   20 | Jack | Technicien | 2020-03-06 18:24:46 | 3000 | 2000 |    2 |
|   30 | Jim  | Vendeur    | 2020-03-06 18:24:46 | 5000 | 5000 |    1 |
|   40 | Lucy | Ingenieur  | 2020-03-06 18:24:46 | 5000 | 5000 |    3 |
|   50 | Joe  | Ingenieur  | 2020-03-07 13:47:24 | 4000 | 3000 |    3 |
|   60 | Jack | Technicien | 2020-03-07 13:47:24 | 3000 | 2000 |    3 |
|   70 | Jim  | Vendeur    | 2020-03-07 13:47:24 | 5000 | 5000 |    3 |
+------+------+------------+---------------------+------+------+------+
7 rows in set (0.00 sec)

mysql&gt;


I want to select the department that contains the three professions the department which has as profession Ingenieur(Engineer), (Technicien) Technician and (Vendeur) seller
my sql request

SELECT DNO as DEPTOUTPROF FROM employe WHERE(PROF = "Ingenieur" and PROF = "Technicien" and PROF = "Vendeur") ;


I expect to have 3 but it shows me Empty set (0.00 sec) and i don't know why ?
Your query as it is will always return 0 rows . PROF field cannot be equal to 3 different values at the same time . 
You need something similar to 

select dno 
from employe 
where prof in ('Ingenieur','Technicien','Vendeur') 
group by dno
having count(distinct prof) =3 ;


There are couple more ways to get what you want, you may try them and find which one has better performance .