按日期选择MySQL的更快方法

Question

Right now I'm using:

MONTH(timestamp) = '7'AND YEAR(timestamp) = '2013'

To select by date but I've been told this is a very inefficient way of going about it, especially with a large amount of data. What is a faster way of obtaining the same results?

Thanks.

Answer 1

Create an index on timestamp and then use:

where timestamp >= '2013-07-01' and timestamp < '2013-08-01'

This will use the index and perform well.

You create the index as:

create index <your table name>_timestamp on <your table name>(timestamp);

Answer 2

The problem is that it applies a function on every comparison. You can fix this with:

1. Not calling a function:

    where timestamp between date '2013-07-01' and date '2013-07-31' 

2. Another way: create funcitonal index:

    create index myIndex on myTable(MONTH(timestamp),YEAR(timestamp)); 

For info: Is it possible to have function-based index in MySQL?

Answer 3

Search for the range of dates, inclusive of 7/1 and exclusive of 8/1.

WHERE timestamp >= '2013-07-01' and timestamp < '2013-08-01'

Mysql helpfully automatically parses the date from YYYY-MM-DD foramt.