将SQL写入关系代数
如何将此SQL查询写入关系代数将SQL写入关系代数,sql,relational-algebra,Sql,Relational Algebra,如何将此SQL查询写入关系代数 Select Distinct S.Name From Student S, Transcript T1, Transcript T2 WHERE T1.StudId = S.Id AND T2.StudId = S.Id And (T1.Semester =’S1997’ AND T2.Semester = ’F1998’) 当我无法测试它,并且我不知道您的关系模式时,要说出精确的表达式有点困难,但请尝试这样的smth \project_{Name} {
Select Distinct S.Name
From Student S, Transcript T1, Transcript T2
WHERE T1.StudId = S.Id AND T2.StudId = S.Id And
(T1.Semester =’S1997’ AND T2.Semester = ’F1998’)
当我无法测试它,并且我不知道您的关系模式时,要说出精确的表达式有点困难,但请尝试这样的smth
\project_{Name}
{
{
Student \join_{Id = StudId} \select_{Semester='S1997'} Transcript
} \join_{Id = StudId}
{
\select_{Semester='F1998'} Transcript
}
}
当我无法测试它,并且我不知道您的关系模式时,要说出精确的表达式有点困难,但请尝试这样的smth
\project_{Name}
{
{
Student \join_{Id = StudId} \select_{Semester='S1997'} Transcript
} \join_{Id = StudId}
{
\select_{Semester='F1998'} Transcript
}
}