java - Jtable 和 MySql

Question

当我尝试执行以下编码时，我遇到了错误。我无法理解这个 netbeans 错误。错误如下。

Mar 21, 2013 2:28:19 AM timetable.generator.JFTTGenerator6 jButton2ActionPerformed
SEVERE: null
java.sql.SQLException: Before start of result set
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073)

请帮我 ！！！！

String subj=(String) jTable1.getValueAt(0,1 );
Connection con = Driver.connect();
ResultSet lec1=Handler.getData(con,
"select lec_id from lecdetails,subjects where subjects.sub_code=lecdetails.sub_code 
 and subjects.sub_name='"+subj+"'");
ResultSet rst1= Handler.getData(con, "select sub_name from subjects,lecdetails 
where subjects.sub_code=lecdetails.sub_code and subjects.sem='2nd' and 
lecdetails.lec_id  <> '"+lec1.getString(1) +"' order by rand() limit 1 ");
jTable2.setValueAt(lec1.getString(1), 0, 1);

Answer 1

在使用之前lec.getString(1)，你必须打电话next()。

所以，在声明之前 ResultSet rst1= Handler.getData，

添加

if (lec1.next()){
    //second result set statement.
    //set value in jtable
}