[英]php merge arrays based on matching column name with multiple entries or duplicates
[英]PHP/MySQL matching cell based on column name
我有一個看起來像這樣的數據庫。
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
當最終用戶插入一個值時,我想將x變量與x列中的值匹配,將另一個變量與數字列名匹配。
那么我該如何編寫一個執行此操作的SQL查詢呢?
SELECT * FROM times_tables WHERE x=4 and COLUMN_NAME=4;
謝謝 :)
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
輸出:
4
---
16
因此,在您的情況下,查詢可能是這樣的:
SELECT `{$col}` FROM `times_tables` WHERE `x` = {$row};
UPD:
可以使用純SQL完成:
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:您可以將SQL包裝到存儲過程中,以獲得更好的保護。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.