基于列名称的PHP / MySQL匹配单元格

Question

I have a database that looks like this.

 x  2  3  4  5
 4  8 12 16 20
 5 10 15 20 25
 6 12 18 24 30
 7 14 21 28 35

When an end user plugs in one value I want to match the x variable to the values in the x column and the other variable to the numerical column names.

So how would I go about writing an SQL query that does this?

SELECT * FROM times_tables WHERE x=4 and COLUMN_NAME=4;

Thanks :)

Answer 1

SELECT
    `4`
FROM
    (SELECT
        4 as `x`, 8 as `2`, 12 as `3`, 16 as `4`, 20 as `5`
    UNION ALL
        SELECT 5, 10, 15, 20, 25
    UNION ALL
        SELECT 6, 12, 18, 24, 30
    UNION ALL
        SELECT 7, 14, 21, 28, 35) `times_tables`
WHERE
    `x` = 4

Output:

4
---
16

So in your case query might be something like this:

SELECT `{$col}` FROM `times_tables` WHERE `x` = {$row};

UPD:

Might be done with pure SQL:

SET @r = 4; -- row
SET @c = 5; -- col

SET @qry = CONCAT('SELECT `', @c ,'` FROM `times_tables` WHERE `x` = ', @r);

PREPARE stmt FROM @qry;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

PS: You may wrap SQL into a stored procedure for better protection.