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 Выбрать такие проекты, где количество задач в проекте больше или равно 3 (Используем group by, having count в SQL запросе) 
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обновлено: 7 February 2019
Таблица Projects
Id
ProjectName
1
Project1
2
Project2
3
Project3
4
Project4
Таблица Tasks
Id
TaskName
Estimate
ProjectId
1
AAAAA for proj1
10
1
2
BBBBBB for proj1
6
1
3
CCCCC for proj1
2
1
4
EEEEEE for proj2
8
2
5
FFFFFF for proj2
9
2
6
IIIIIIIII for proj3
3
3
7
JJJJJJJ for proj3
18
3
8
KKKKKK for proj3
1
3
9
LLLLLLL for proj3
7
3
10
MMMMM for proj3
6
3
11
NNNNNN for proj4
2
4
Выбрать такие проекты, где количество задач в проекте больше или равно 3
  SQL запрос
select ProjectId, count(TaskName) as TaskCount from Tasks group by ProjectId having count(TaskName)>=3
Результат SQL запроса
ProjectId
TaskCount
1
3
3
5
 
 
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inner join, left join, right join, outter join in a SQL query
 
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