PDO php questions?

Question

PHP

Small code, search by TIMESTAMP type field:

$a = '2007-08-09 01:00:00';
$b = '2007-08-09 08:00:00';
    
$st = $pdo->prepare('set profiling=1');
$st->execute();
    
$st = $pdo->prepare('SELECT `mytime` FROM `date` WHERE `mytime` BETWEEN a=:a AND b=:b ');
$st->bindParam(':a', $a, PDO::PARAM_STR);
$st->bindParam(':b', $b, PDO::PARAM_STR);
$st->execute();
$RES = $st->fetchAll();

Direct query to the view database

SELECT `mytime` FROM `date` WHERE `mytime` BETWEEN '2007-08-09 01:00:00' AND '2007-08-09 08:00:00'

works fine, but:
1) How to enable profiling set profiling=1 to see the query itself, you need to send a command in the same query somehow, profiling did not work for me like this
2) SQLSTATE[42000]: Syntax error on the query itself error or access violation: 1064 check the manual that corresponds to your MySQL server version for the right syntax to use near '='2007-08-09 01:00:00' AND b='2007-08-09 08:00:00'' at line 1
I can't understand what exactly he doesn't like in this request
3)Question on PDO::PARAM_STR I tried not to specify this parameter in other working requests, for example $b->bindParam(":email",$email); and everything works, then it is needed, not needed? It is clear that it specifies the data type (string, number, boolean, etc.)

Answer 1

1) dev.mysql.com/doc/refman/5.7/en/show-profile.html
2) between is written like this: dev.mysql.com/doc/refman/5.7/en/comparison-operato...
Compare with yours .
3) php.net/manual/en/pdostatement.bindparam.php , $data_type = PDO::PARAM_STR. Is there anything else that needs to be explained?