In the following table we record studentname, lecture_subject and presenting_date.
table: studentlectures
We need a query to remove a lecturer who was presented less than a month on the same subject and by the same student. So we will get the following result:
As you see records 4 and 6 are not shown because the same subject is presented by the same student in less than 30 days after the date when that subject was presented by the same student. For example record 6 is not shown because john had presented politics only 24 days before. Can we make this query?
Thank you,
table: studentlectures
Code:
ID studentname subject, lecturedate
1 john politics, 1/1/12
2 steve politics, 16/1/12
3 steve economics, 21/1/12
4 steve politics, 22/1/12
5 john economics, 22/1/12
6 john politics, 25/1/12
7 john politics, 3/2/12Code:
ID studentname subject, lecturedate
1 john politics, 1/1/12
2 steve politics, 16/1/12
3 steve economics, 21/1/12
5 john economics, 22/1/12
7 john politics, 3/2/12Thank you,