SQL Serverの：いくつかの条件

Question

考えるとテーブルCollegeMajors

| Id | Major  | 
|----|-------------| 
| 1 | Accounting | 
| 2 | Math  | 
| 3 | Engineering | 

とEnrolledStudents

| Id | CollegeMajorId | Name   | HasGraduated | 
|----|----------------|-----------------|--------------| 
| 1 | 1    | Grace Smith  | 1   | 
| 2 | 1    | Tony Fabio  | 0   | 
| 3 | 1    | Michael Ross | 1   | 
| 4 | 3    | Fletcher Thomas | 1   | 
| 5 | 2    | Dwayne Johnson | 0   | 

は私が

Select 
    CollegeMajors.Major, 
    Count(select number of students who have graduated) AS TotalGraduated, 
    Count(select number of students who have not graduated) AS TotalNotGraduated 
From 
    CollegeMajors 
Inner Join 
    EnrolledStudents On EnrolledStudents.CollegeMajorId = CollegeMajors.Id 

のようなクエリをしたい、関連テーブルの列のカウントを（）を取得

と私はこれらの結果を期待しています

| Major  | TotalGraduated | TotalNotGraduated | 
|-------------|----------------|-------------------| 
| Accounting | 2    | 1     | 
| Math  | 0    | 1     | 
| Engineering | 1    | 0     | 

したがって、質問はどのような質問が上記を達成するためにCOUNTの内部に入るのですか？

Answer 1

Select CollegeMajors.Major 
    , COUNT(CASE WHEN EnrolledStudents.HasGraduated= 0 then 1 ELSE NULL END) as "TotalNotGraduated", 
    COUNT(CASE WHEN EnrolledStudents.HasGraduated = 1 then 1 ELSE NULL END) as "TotalGraduated" 
From CollegeMajors 
InnerJoin EnrolledStudents On EnrolledStudents.CollegeMajorId = CollegeMajors.Id 
GROUP BY CollegeMajors.Major 

Answer 2

あなたは希望result.Pleaseは、以下の更新クエリを試す達成するために、あなたのCOUNT内CASEステートメントを使用することができます。

Select CollegeMajors.Major 
    , COUNT(CASE WHEN EnrolledStudents.HasGraduated= 0 then 1 ELSE NULL END) as "TotalNotGraduated", 
    COUNT(CASE WHEN EnrolledStudents.HasGraduated = 1 then 1 ELSE NULL END) as "TotalGraduated" 
From CollegeMajors 
InnerJoin EnrolledStudents On EnrolledStudents.CollegeMajorId = CollegeMajors.Id 
GROUP BY CollegeMajors.Major 

Answer 3

あなたは卒業し、カウントのためにこれを試すことができます：いいえ、あなたがして、グループを持っている必要があり

Select Count(*) From EnrolledStudents group by CollegeMajorId having HasGraduated = 0