Question

I have a typical transaction of

START TRANSACTION
INSERT INTO ...
UPDATE ...
DELETE ...
COMMIT

Problem 1: Failure in UPDATE will not block the transaction. In single query, I use mysql_affected_rows() to inspect the success of UPDATE but how to do so in the middle of a Transaction?

Problem 2: How to detect which query caused the transaction stop? To make a if condiction in PHP?

Answer 1

Assuming you are using the mysql_*() functions based on your mention of mysql_affected_rows(), you should simply be calling each stage of the transaction in its own mysql_query() and checking its success or failure at each stage. Unless you wrap this as a stored procedure, you have to call these as individual statements since mysql_query() doesn’t support multiple statements in one call.

function doTransaction() {
  mysql_query("START TRANSACTION;");
  $ins = mysql_query("INSERT INTO ....");
  if (!$ins) {
    // fail
    mysql_query("ROLLBACK");
    return FALSE;
  }

  $upd = mysql_query("UPDATE...");
  if (!$upd) {
    // fail
    mysql_query("ROLLBACK");
    return FALSE;  
  }
  if (mysql_affected rows() === 0) {
    // no rows updated, rollback if necessary
    mysql_query("ROLLBACK");
    return FALSE;
  }

  $del = mysql_query("DELETE FROM...");
  if (!$del) {
    // fail
    mysql_query("ROLLBACK");
    return FALSE;
  }

  // All succeeded
  mysql_query("COMMIT");
  return TRUE;
}