jdbc - MySQL syntax error when executing SQL query

Question

When I try to run the code below I am getting:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?' at line 1`

String query="Select * from DB.Admin where username = ?";
PreparedStatement st=connection.prepareStatement(query);
st.setString(1,request.getParameter("loginid"));
ResultSet rst= st.executeQuery(query);
int count=0;
while(rst.next()){
   count++;
}

Please help me in this.

Answer 1

You will have to remove the query argument from your executeQuery call. If you provide the parameter, the query will be executed without binding any values (see Statement for details) - this is why the syntax (i.e. the ?) is invalid.

Execute the query like this:

ResultSet rst = st.executeQuery();

As a side note: you should always wrap Connection, PreparedStatement and ResultSet with a try-with-resources block, e.g.

try (ResultSet rst = st.executeQuery()) {
    // read the results
}

This way you can be sure the ResultSet will be closed no matter what happens.