MySQL 查询用于计算一行中值的平均值?
mysqlmysqli database
要在 MySQL 中计算一行中值的平均值，请使用以下语法
SELECT (yourTableName.yourColumnName1+yourTableName.yourColumnName2+yourTableName.yourColumnName3+,..........N)/numberOfColumns AS anyAliasName FROM yourTableName;
为了理解上述语法，让我们创建一个表。创建表的查询如下
mysql> create table calculateAverageDemo -> ( -> x int, -> y int, -> z int -> ); Query OK, 0 rows affected (1.41 sec)
使用 insert 命令在表中插入一些记录。
查询如下
mysql> insert into calculateAverageDemo values(10,20,30); Query OK, 1 row affected (0.78 sec) mysql> insert into calculateAverageDemo values(40,50,70); Query OK, 1 row affected (0.26 sec) mysql> insert into calculateAverageDemo values(80,90,220); Query OK, 1 row affected (0.43 sec)
使用 select 语句显示表中的所有记录。
查询如下
mysql> select *from calculateAverageDemo;
以下是输出 −
+------+------+------+ | x | y | z | +------+------+------+ | 10 | 20 | 30 | | 40 | 50 | 70 | | 80 | 90 | 220 | +------+------+------+ 3 rows in set (0.00 sec)
这是计算一行中平均值的查询
mysql> select (calculateAverageDemo.x+calculateAverageDemo.y+calculateAverageDemo.z)/3 -> AS Average from calculateAverageDemo;
以下是输出 −
+----------+ | Average | +----------+ | 20.0000 | | 53.3333 | | 130.0000 | +----------+ 3 rows in set (0.06 sec)
