MySQL retrieve variable from Stored Procedure in PHP PDO

Question 1

I've seen this question asked a load of times, but they're all really long, and I just can't get my head around what they're doing ... So, could someone tell me how to get the LAST_INSERT_ID() from this procedure into php using PDO:

Table:

CREATE TABLE names (
    ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
    name varchar(50) NOT NULL
)

Procedure:

CREATE DEFINER=`root`@`localhost` PROCEDURE `simpleProcedure`(newname varchar(50), OUT returnid INT(11))
BEGIN
    INSERT INTO names (name) VALUES (newname);
    SET returnid = LAST_INSERT_ID();
END

PHP code I've tried:

$stmt=$db->prepare("CALL simpleProcedure(:name,:returnid)");
$stmt->bindValue(':name',$name,PDO::PARAM_STR);
$stmt->bindParam(':returnid',$returnid,PDO::PARAM_INT,11);
$stmt->execute();
echo $returnid;

But, probably obvious to someone who has more brain cells than me, this doesn't work. Any help appreciated.

Reference as to why I believe this SHOULD work:

http://www.php.net/pdo.prepared-statements (Example #4)

Question 2

It turns out that this is a bug that has been going on for a long time... since 2005!

Here is the original bug report: 2005 through to 2013. And here is the new bug report: From 2013 to the present.

There are various approaches to getting the answer returned, I found one of them and demonstrate it...

The 'trick' is that to get the output from a 'mysql' procedure. It is a 'two stage' process.

The first part is to run the procedure with your inputs, and also tell it what MYSQL variables to store the result in.
Then, you run a separate query to 'select' those 'mysql' variables.

It is described quite clearly here: php-calling-mysql-stored-procedures

Update (Jan 2017):

Here is an example showing the use of variables for 'IN', 'INOUT' and 'OUT' Mysql procedure parameters.

Before we start here are some tips:

When developing: Run PDO in 'emulates mode' as it is more reliable at determining errors in the procedure call.
Only bind PHP variables to the procedure 'IN' parameters.

You will get some really odd runtime errors when you try binding variables to INOUT and OUT parameters.

As usual I tend to provide rather more comments than are required ;-/

Runtime Environment (XAMPP):

PHP: 5.4.4
Mysql: 5.5.16

Source Code:

SQL Procedure
PHP with output

SQL Code:

CREATE PROCEDURE `demoSpInOutSqlVars`(IN     pInput_Param  INT, /* PHP Variable will bind to this*/   
                                      /* --- */  
                                      INOUT  pInOut_Param  INT, /* contains name of the SQL User variable that will be read and set by mysql */
                                      OUT    pOut_Param    INT) /* contains name of the SQL User variable that will be set by mysql */
BEGIN
    /*
     * Pass the full names of SQL User Variable for these parameters. e.g. '@varInOutParam'
     * These 'SQL user variables names' are the variables that Mysql will use for:
     *    1) finding values
     *    2) storing results
     *
     * It is similar to 'variable variables' in PHP.  
     */
     SET pInOut_Param      := ABS(pInput_Param) + ABS(pInOut_Param); /* always positive sum  */
     SET pOut_Param        := ABS(pInput_Param) * -3;                /* always negative * 3  */ 
END$$

PHP Code:

DB Connection:

$db = appDIC('getDbConnection', 'default'); // get the default db connection
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, true);    
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);

Note: The output is the same with EMULATE_PREPARES = false.

Set all PHP Variables that will be used:

$phpInParam     = 5;                  
$phpInOutParam  = 404;          /* PHP InOut variable  ==> read and should be changed  */
$phpOutParam    = null;         /* PHP Out   variable  ==> should be changed           */

Define and Prepare the SQL procedure call:

$sql = "call demoSpInOut(:phpInParam, 
                         @varInOutParam, /* mysql variable name will be read and updated */
                         @varOutParam)"; /* mysql variable name that will be written to  */

$stmt = $db->prepare($sql);

Bind PHP Variables and Set SQL Variables:

1) bind the PHP variables

$stmt->bindParam(':phpInParam', $phpInParam, PDO::PARAM_INT);
2) Set the SQL User INOUT variables

$db->exec("SET @varInOutParam = $phpInOutParam"); // This is safe as it just sets the value into the MySql variable.

Execute the procedure:

$allOk = $stmt->execute();

Get the SQL Variables into the PHP variables:

$sql = "SELECT @varInOutParam AS phpInOutParam,
               @varOutParam   AS phpOutParam
        FROM dual";
$results = current($db->query($sql)->fetchAll());

$phpInOutParam = $results['phpInOutParam'];
$phpOutParam   = $results['phpOutParam'];

Note: maybe not the best way ;-/

Display the PHP variables

"$phpInParam:"     => "5"
"$phpInOutParam:"  => "409"
"$phpOutParam:"    => "-15"

Question 3

The following works for me:

<?php

$pdo = new PDO("mysql:host=localhost;dbname=test", "root", "pass");
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);

$stmt = $pdo->prepare("INSERT INTO `null_test` (`can_be_null`) VALUES (:null)");
$stmt->bindValue(":null", null, PDO::PARAM_NULL);

$stmt->execute();

Pass in PHP's null, with type of PDO::PARAM_NULL. Also, make sure your prepare emulation is set to false. That might help.

Question 4

lastInsertId() is a method of the PDO class, not the PDOStatement class.

This should work:

$groupID = $dbo->lastInsertId();

Question 5

Are you sure you're using the same database? Try simplifying it to a basic example, e.g.,

$m = new Mongo();
$db = $m->foo;

$db->system->js->save(array("_id"=>"archiveMessages", 
   "value"=>new MongoCode("function() { return 3; }")));

print_r($db->execute("archiveMessages()"));

Results in:

Array
(   
    [retval] => 3
    [ok] => 1
)

Question 6

It seems like there's no good simple way to do this, without a hack or a major paradigm shift. It looks like the best way is to just split out the original procs and end up with one more proc than before:

Old way:

create procedure dbo.GetSomething
as
begin
    select * from dbo.Person;
    select * from dbo.Car;
end;

New way:

create procedure dbo.GetPeople
as
begin
    select * from dbo.Person;
end;

create procedure dbo.GetCars
as
begin
    select * from dbo.Car;
end;

-- This gives the same result as before
create procedure dbo.GetSomething
as
begin
    exec dbo.GetPeople;
    exec dbo.GetCars;
end;

Then when I'm in a different proc and need both result sets, I'd just have to call them one at a time.