[[XST]O_x]

Well, amount should be a float.

pawn Код:

new Float: amount;

//Speedvalue[playerid] should also be defined as a Float

And I'm not sure which version of MySQL you're using, but I'm pretty sure 'format' should be 'mysql_format':

pawn Код:

mysql_format(handleid, gsQuery, sizeof gsQuery, "UPDATE `accounts` SET `Speedvalue` = %f WHERE `Key` = %d",Speedvalue[playerid],PlayerInfo[ playerid ][ AccID ]);

mysql_query(handleid, gsQuery);