Three tables, a s, student's name and serial number, a c, curriculum and the serial number, a sc, student number, course number, achievement
Don't exist, group by, having, etc., only the most simple select, from, where, and, or, than size, occurring simultaneously set to writing,
Help fellow teachers,
thank you

CodePudding user response:

Is divided into two steps to do the best, the total number of courses first calculated, then total number of statistics student elective course, make the subquery,
Must write step can also, it is too many SQL, tired

CodePudding user response:

reference 1st floor SuperDay response:

is divided into two steps to do the best, the total number of courses first calculated, then total number of statistics student elective course, make the subquery,
Must write step can also, it is too many SQL, look tired

If it is not can use the count, how statistics?

CodePudding user response:

Don't count it in or not in