可以计算MySQL数据库中列的平均值的PHP脚本

Question

我需要一些关于如何编写我的 php 脚本的帮助，以便它可以找到 mysql 数据库中六列的平均值并将新结果存储在 mysql 数据库中的新列中。

例如

MSQL 数据库具有以下列

 Name    EXAM1       EXAM2     EXAM3    EXAM4    EXAM5

然后将以下记录输入到数据库中

 Name    EXAM1       EXAM2     EXAM3    EXAM4    EXAM5


Eric     10          20        10        20       10

然后PHP脚本会生成这个结果

 Name    EXAM1       EXAM2     EXAM3    EXAM4    EXAM5     AVERAGE


Eric     10          20        10        20       10         14

这样在 MYSQL 数据库中，记录将像 PHP 脚本结果一样显示。

有什么帮助吗？

谢谢。

Answer 1

你可以直接用 SQL 来做

UPDATE yourTable set AVERAGE = (EXAM1+EXAM2+EXAM3+EXAM4+EXAM5)/5;

或者如果你像这样定义你的表，你会自动生成 AVERAGE：

CREATE TABLE yourTable (
  title VARCHAR(32) DEFAULT NULL,
  exam1 DOUBLE,
  exam2 DOUBLE,
  exam3 DOUBLE,
  exam4 DOUBLE,
  exam5 DOUBLE,
  average DOUBLE GENERATED ALWAYS AS ((exam1 + exam2 + exam3 + exam4 + exam5) / 5 ) STORED
);

样本

mysql> CREATE TABLE yourTable (
    ->   title VARCHAR(32) DEFAULT NULL,
    ->   exam1 DOUBLE,
    ->   exam2 DOUBLE,
    ->   exam3 DOUBLE,
    ->   exam4 DOUBLE,
    ->   exam5 DOUBLE,
    ->   average DOUBLE GENERATED ALWAYS AS ((exam1 + exam2 + exam3 + exam4 + exam5) / 5 ) STORED
    -> );
Query OK, 0 rows affected (0,02 sec)

mysql> INSERT INTO yourTable (title, exam1, exam2, exam3, exam4, exam5)
    -> VALUES('test1',1,1,22,33,44),('Test2',333,24,11,45,97);
Query OK, 2 rows affected (0,00 sec)
Records: 2  Duplicates: 0  Warnings: 0

mysql>
mysql> SELECT * FROM yourTable;
+-------+-------+-------+-------+-------+-------+---------+
| title | exam1 | exam2 | exam3 | exam4 | exam5 | average |
+-------+-------+-------+-------+-------+-------+---------+
| test1 |     1 |     1 |    22 |    33 |    44 |    20.2 |
| Test2 |   333 |    24 |    11 |    45 |    97 |     102 |
+-------+-------+-------+-------+-------+-------+---------+
2 rows in set (0,00 sec)

mysql>