哪位高手能告之sql中max的作用谢谢急用
如:
try
{
stmt.execute(sqlStr);
sqlStr = "select max(id) from My_users where username = '" +user.getUserName()+ "'";
rs = stmt.executeQuery(sqlStr);
while (rs.next())
{
userid = rs.getLong(1);
}
rs.close();
return true;
}
如:
try
{
stmt.execute(sqlStr);
sqlStr = "select max(id) from My_users where username = '" +user.getUserName()+ "'";
rs = stmt.executeQuery(sqlStr);
while (rs.next())
{
userid = rs.getLong(1);
}
rs.close();
return true;
}
sample:id username
========================
1 csdn
2 csdn
3 other
执行:
select max(id) from My_users where username = 'csdn'";
结果: 2