MYSQL更新记录错误：无法重新打开表（临时表）

Question

Before I get to my question I want you to know that I started learning MYSQL and PHP last week so it could be some of the worst coding you've seen in a while.

Enough with the excuses, here's my problem, while Executing the following PHP script:

           if($hdd!==0){
                  $sql="CREATE TEMPORARY TABLE custom AS SELECT * from `builds`;";
                $conn->query($sql);
                 if($hdd==1){
                 $sql="UPDATE custom SET HDD = null;";
                $conn->query($sql);
            }

                $conn->query("DROP PROCEDURE IF EXISTS ROWPERROW2;");
$conn->query("CREATE PROCEDURE ROWPERROW2()
BEGIN
DECLARE n INT DEFAULT 0;

DECLARE i INT DEFAULT 1;
DECLARE price INT DEFAULT 0;

SELECT COUNT(*) FROM custom INTO n;
SET i=1;

SET price=0;
WHILE i<=n DO 
SET price = (SELECT sum(`lowestPrice`) FROM ((SELECT `lowestPrice` FROM products WHERE name IN (SELECT `Motherboard` from `custom` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `Cooling` from `custom` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `PC_Case` from `custom` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `PSU` from `custom` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `GPU` from `custom` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `Memory` from `custom` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `SSD` from `custom` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `HDD` from `custom` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `CPU` from `custom` Where `id`=i ))) as A);
UPDATE custom SET `TotalPrice`=price WHERE `id`=i;
SET i = i + 1;
END WHILE;
End;");
                if ($conn->query("CALL ROWPERROW2();") === TRUE) {
    echo "Builds Record updated successfully";
} else {
    echo "Error updating record: " . $conn->error;
}
            }

I get the following error:

Error updating record: Can't reopen table: 'custom'

"custom" is a temporary table, so I guess that's what causing the problem, how can I work my way around it? I can't just create a normal table each time because I want it to work on a multi-user environment

Answer 1

Found a work around, it's not pretty, but it works. What I did was creating multiple temporary tables based on the original temp table ('contents'), and then used them in the procedure so each table is used only once, like so:

                 $conn->query(" CREATE TEMPORARY TABLE t1 AS SELECT * FROM custom;");
                 $conn->query(" CREATE TEMPORARY TABLE t2 AS SELECT * FROM custom;");
                $conn->query(" CREATE TEMPORARY TABLE t3 AS SELECT * FROM custom;");
                $conn->query(" CREATE TEMPORARY TABLE t4 AS SELECT * FROM custom;");
                $conn->query(" CREATE TEMPORARY TABLE t5 AS SELECT * FROM custom;");
                $conn->query(" CREATE TEMPORARY TABLE t6 AS SELECT * FROM custom;");
                $conn->query(" CREATE TEMPORARY TABLE t7 AS SELECT * FROM custom;");
                $conn->query(" CREATE TEMPORARY TABLE t8 AS SELECT * FROM custom;");
                $conn->query(" CREATE TEMPORARY TABLE t9 AS SELECT * FROM custom;");

And changed the procedure so it'd use each table only once:

$conn->query("CREATE PROCEDURE ROWPERROW2()
BEGIN
DECLARE n INT DEFAULT 0;

DECLARE i INT DEFAULT 1;
DECLARE price INT DEFAULT 0;

SELECT COUNT(*) FROM builds INTO n;
SET i=1;

SET price=0;
WHILE i<=n DO 
SET price = (SELECT sum(`lowestPrice`) FROM ((SELECT `lowestPrice` FROM products WHERE name IN (SELECT `Motherboard` from `t1` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `Cooling` from `t2` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `PC_Case` from `t3` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `PSU` from `t4` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `GPU` from `t5` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `Memory` from `t6` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `SSD` from `t7` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `HDD` from `t8` Where `id`=i )) UNION (SELECT `lowestPrice` FROM products WHERE name IN (SELECT `CPU` from `t9` Where `id`=i ))) as A);
UPDATE custom SET `TotalPrice`=price WHERE `id`=i;
SET i = i + 1;
END WHILE;
End;");
                if ($conn->query("CALL ROWPERROW2();") === TRUE) {
    echo "Builds Record updated successfully";
} else {
    echo "Error updating record: " . $conn->error;
}