MySQL-选择中每个月的平均值

Question

I have a demo table with a list of dates, the type of toy, age group of toy, and sales figure. I want to grab a list of sales ordered by month, but the average for each month:

Table
Date | Type | Age | Sales
2014-01-04 | Blocks | 3+ | 1000
2014-01-12 | Blocks | 3+ | 2000
2014-01-23 | Blocks | 3+ | 1500
2014-02-04 | Blocks | 3+ | 1000
2014-02-12 | Blocks | 3+ | 3500
2014-02-23 | Blocks | 3+ | 700
2014-03-04 | Blocks | 3+ | 1100
2014-04-12 | Blocks | 3+ | 2100
2014-04-23 | Blocks | 3+ | 1200

Thinking larger scale ie thousands of records, does the below query look right or is there a better way of doing it?

SELECT YEAR(Date) AS MyYear,MONTH(Date) AS MyMonth,AVG(Sales) AS MyValue
FROM SalesTable
WHERE Type LIKE 'Blocks%' AND Age='3+'
GROUP BY MyYear, MyMonth;

Answer 1

Avoid using LIKE unnecessarily. In you sample there is no need for LIKE. This can impact your performance when data grows.

Type LIKE 'Blocks%' 

Also you may want to consider indexing Type and Age column.