从存储过程中遍历MySQL结果

Question

For the sake of simplicity here, I have the following SQL query:

"SELECT id,name FROM employees WHERE birthdate<'$dymd'"

If I want use records from standard (not stored procedure) query, the code looks like this:

$sql="SELECT id,name FROM employees WHERE birthdate<'$dymd'";

$rst=$mysqli->query($sql);

while($row=$rst->fetch_assoc())
{
  ...
}

$rst->free();

But if I store my query into stored procedure:

CREATE PROCEDURE GetEmployees(IN dymd DATE)
  READS SQL DATA
BEGIN
  SELECT id,name FROM employees WHERE birthdate<dymd;
END;

I cannot use previous loop (I get the error message: "Commands out of sync; you can't run this command now"). I have to loop like this:

$sql="CALL GetEmployees('$dymd')";

$rst=$mysqli->query($sql);

if($rst->num_rows)
{
  do
  {
    $row=$rst->fetch_assoc();
    ...
  }
  while($mysqli->next_result());
  $rst->free();
}

The question is why I need to explicitly push records pointer in case of records from stored procedure!? Why fetch_assoc() does not do it for me like in previous case?

Even more, the code above works only for one retrieved result set from stored procedure per PHP page. If I have two stored procedures (eg CALL YoungEmployees() and CALL OldEmployees()) on the same PHP page for the second stored procedure I get the already mentioned error message. If I use standard queries (not from stored procedures) then it works fine - both result sets are correctly presented on one page!

Answer 1

According to @JurisGregov comment, the solution for this is;

//first stored procedure

$sql1="CALL YoungEmployees('$dymd')";

if($rst1=$mysqli->query($sql1))
{
  while($row1=$rst1->fetch_row())
  {
    ...
  }
  $rst1->close();
  $mysqli->next_result(); //!!!
}

//second stored procedure

$sql2="CALL OldEmployees('$dymd')";

if($rst2=$mysqli->query($sql2))
{
  while($row2=$rst2->fetch_row())
  {
    ...
  }
  $rst2->close();
  $mysqli->next_result(); //!!!
}