How to prevent from inserting two similar values into DB?

Question

Hi,
I wanted to know how we can prevent from inseting two similar values into the database, e.g the user id which should be unique. Here is some sample code, Please help me.
String s10 = req.getParameter("T10");
String s11 = req.getParameter("T11");
rs = st.executeQuery("select * from Register where userid='"+s10+"' ");
if(rs.next())
     sos.println("Sorry the user already exists");
else
int x = st.executeUpdate("insert into Register values('"+s1+"','"+s2+"','"+s3+"','"+s4+"','"+s5+"',"+s6+","+s7+",'"+s8+"','"+s9+"','"+s10+"','"+s11+"')");
Thaks in advance
Uma               

Answer 1

Hi reddy
Your code works will be perfect with slight changes whucah are as below:
String s10 = req.getParameter("T10");
String s11 = req.getParameter("T11");
rs = st.executeQuery("select * from Register where upper(userid)='"+s10.toUpperCase()+"' ");
if(rs.next())
sos.println("Sorry the user already exists");
else
int x = st.executeUpdate("insert into Register values('"+s1+"','"+s2+"','"+s3+"','"+s4+"','"+s5+"',"+s6+","+s7+",'"+s8+"','"+s9+"','"+s10+"','"+s11+"')");
In the above Query we will get a unique userids it may be smallcase or Uppercase
This will help u
Cheers
Rambee