动态解析计算

【问题】
Let’s say I have given data as string:

+———-+
|Size |
+———-+
|15X10 |
|5X4 |
|3 |
|2X6X5 |
+———-+

I want to write this column as integer like this:

+———-+
|Size |
+———-+
|150 |
|20 |
|3 |
|60 |
+———-+

Some of them are multiply of three numbers, some of them just one number. I can split the string but cannot make MySQL to calculate the number. Thank you.

【回答】
对于任意的四则运算、带多重括号且多个操作数的运算，用 SQL 很难实现。可以在 SPL 中用动态结构化计算来解决，脚本如下：

	A
1	$select * from tb
2	=A1.run(Size=eval(replace(Size,"X","*")))

A1：查询 tb 表

A2：将字符 X 替换为乘法符号 *，对字符串动态解析为表达式并计算