I have two tables the first one is for "course" and the other is for "exam":
I want select exams which are matched to the code, of course, get by entering its name (nomCours)
here is my code:
try {
String select1 = "select code from cours where nomCours=?";
st2 = con.prepareStatement(select1);
st2.setString(1, nom);
rs2 = st2.executeQuery();
System.out.println(rs2.getInt("code"));
String select = "SELECT matricule FROM examen where code=?";
st = con.prepareStatement(select);
st.setInt(1, rs2.getInt("code"));
rs = st.executeQuery();
while (rs.next()) {
System.out.print(rs.getInt("matricule")+" ");
}
} catch (SQLException ex) {
System.err.print(ex);
}
this doesn't work, and it gives me this error:
java.sql.SQLException: Before start of result set
When you execute a query, you get a ResultSet
that points to the so-called before-first row. You need to advance it in order to get the first row of the result:
rs2 = st2.executeQuery();
if (rs2.next()) {
System.out.println(rs2.getInt("code"));
}
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.