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Informasjon

Forfatter(e) Quentin Cappart
Frist Ingen frist
Innleveringsgrense Ingen begrensning

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Compréhension des mots-clefs (gestion des valeurs manquantes)

Parmi les propositions suivantes, trouvez celle donnant une description correcte des mots-clefs (ou requêtes) suivants.

Spørsmål 1: 
select name
from instructor
where salary = null;
Spørsmål 2: 
select name
from instructor
where salary is null;
Spørsmål 3: 
select name
from instructor
where not (salary > 80000);
Spørsmål 4: 
select ID
from student
where tot_cred > 60
      or tot_cred is null;
Spørsmål 5: 
select name
from instructor
where dept_name <> 'Biology';
Spørsmål 6: 
select name
from instructor
where salary > 80000
      and dept_name = 'Biology';

On suppose qu’un instructeur spécifique a salary = NULL et dept_name = 'Biology'.

Spørsmål 7: 
select name
from instructor
where salary > 80000
      or dept_name = 'Biology';

On suppose qu’un instructeur spécifique a salary = NULL et dept_name = 'Biology'.

Spørsmål 8: 
select name
from instructor
where not (salary > 80000);

On suppose qu’un instructeur spécifique a salary = NULL.

Spørsmål 9: 
select ID
from student
where (tot_cred > 60 and dept_name = 'Biology')
      or tot_cred is null;

On suppose qu’un étudiant spécifique a tot_cred = NULL et dept_name = 'Biology'.

Spørsmål 10: 
select name
from instructor
where salary < 50000
      and dept_name = 'Physics';

On suppose qu’un instructeur spécifique a salary = NULL et dept_name = 'Chemistry'.