Código PHP:
Statement st = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSI TIVE, ResultSet.CONCUR_READ_ONLY);
String consul = "SELECT COUNT(Rfc_av) FROM aval WHERE Rfc_av LIKE '%"+bus_cta+"%'";
rs = st.executeQuery (consul);
while(rs.next()){
if(rs.getInt("COUNT(Rfc_av)")
{
javax.swing.JOptionPane.showMessageDialog(this, "El aval si existe");
} else {
javax.swing.JOptionPane.showMessageDialog(this, "El aval no existe");
}
]