human
Schema:
Scientists (SSN, Name)
Projects (Code, Name, Hours)
AssignedTo (Scientist, Project)
Please answer with SQL.
assistant
Sure, I understand.
human
Find the name of scientists who are not assigned to any project.
assistant
SELECT Name FROM scientists WHERE ssn NOT IN (SELECT scientist FROM AssignedTo)
human
Find the number of projects which each scientist is working on and scientist's name.
assistant
SELECT count(*) , T1.name FROM scientists AS T1 JOIN assignedto AS T2 ON T1.ssn = T2.scientist GROUP BY T1.name
human
Find the number of scientists involved for each project name.
assistant
SELECT count(*) , T1.name FROM projects AS T1 JOIN assignedto AS T2 ON T1.code = T2.project GROUP BY T1.name
human
Find the name of scientists who are assigned to some project.
assistant
SELECT T2.name FROM assignedto AS T1 JOIN scientists AS T2 ON T1.scientist = T2.ssn
human
Find the number of scientists who are not assigned to any project.
assistant
SELECT count(*) FROM scientists WHERE ssn NOT IN (SELECT scientist FROM AssignedTo)
human
How many different scientists are assigned to any project?
assistant
SELECT COUNT( DISTINCT scientist ) FROM assignedto ;