if()函数返回的是选择出来的结果,你这样写,中间加了逗号,就会导致结果变成and classno = "",and studentno = "",这样sql肯定是不认识的,把逗号去掉就可以了.
以下是参考例子,希望对你有帮助
${IF(classno == "","group by classno","and classno = '"+classno + "'")}
${IF(studentno == "","","and studentno in ('"+studentno + "')")}
PS,写两个IF会更直观一些