I have the following tables
我有以下表格
R:
rid, wid, sid, attend
1 1 3 1
2 1 2 0
3 2 3 1
4 3 1 0
5 2 1 1
6 4 1 1
E:
eid, wid,sid
1 1 3
2 2 1
W:
wid, title
1 title1
2 title2
3 title3
4 title4
R:
rid,
