What's mysql's “BETWEEN” performance over.

问题:

Is there any better performance when querying in (particularly) mysql of the following:

SELECT * FROM `table` WHERE `unix_date` BETWEEN 1291736700 AND 1291737300

over:

SELECT * FROM `table` WHERE `unix_date` >= 1291736700 AND `unix_date` <= 1291737300

or BETWEEN syntax is just being substituted with the second sql?

回答1:

As I recall, there's no difference. But see for yourself if:

explain plan for 
SELECT * FROM `table` WHERE `unix_date` BETWEEN 1291736700 AND 1291737300

and:

explain plan for
SELECT * FROM `table` WHERE `unix_date` >= 1291736700 AND `unix_date` <= 1291737300

produce the same plans.

回答2:

From the documentation:

• expr BETWEEN min AND max

If expr is greater than or equal to min and expr is less than or equal to max, BETWEEN returns 1, otherwise it returns 0. This is equivalent to the expression (min <= expr AND expr <= max) if all the arguments are of the same type. Otherwise type conversion takes place according to the rules described in Section 11.2, “Type Conversion in Expression Evaluation”, but applied to all the three arguments.

So it really is just syntax sugar.

回答3:

BETWEEN shows clearer intent and reads better (something SQL set out to do).

回答4:

The three following statement will produce the same result:

1. i BETWEEN x AND y
2. x <= i AND i <= Y
3. i >= x AND i <= Y

But in configuration 3 mysql might (depending on your indexes) use different indexes: order matters and you should be testing with EXPLAIN query to see the difference