mysql 数据库对行求和,MySQL-如何创建自动对行求和的列？-程序员宅基地

I have a mysql database table called "character" with columns like name, strength, intelligence, skill. I want to create a column that sums up strength, intelligence and skill AUTOMATICALLY. Is this possible?

I have seen loads of pages showing how to do queries. I did a query just fine, such as

select (str+intel+skl) as sum from character;

It returns a sum just fine.

But what I'm missing (don't understand) is how to:

either AUTOMATE that query into my mysql db (for example, when I do "select * from character", it will show "strength, intelligence, skill, sum"),

OR where/how to incorporate the mysql query into my rails app so that SUM shows up in real time, and when edits to, for e.g. strength occur, the SUM is updated accordingly.

A key point, I am summing columns across a row (strength, intelligence, skill), not summing a column (strengths of several characters).

解决方案

This should work, if I'm understanding your question correctly and the strength, intelligence, skill columns are numeric data types.

select strength, intelligence, skill, strength+intelligence+skill as sum

from character

As suggested, a view could then be created pretty easily with:

create view totals as

select strength, intelligence, skill, strength+intelligence+skill as sum

from character

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