Question: Is there a performance difference between using a BETWEEN clause or using <= AND >= comparisons?

i.e. these two queries:

```
SELECT *  
  FROM table  
 WHERE year BETWEEN '2005' AND '2010';  

```

...and

```
SELECT *  
  FROM table  
 WHERE year >= '2005' AND year <= '2010';

```

In this example, the year column is VARCHAR2(4) with an index on it.

Answer: 
When in doubt (for Oracle anyway), run an [explain plan](http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/ex_plan.htm) and you'll see what the optimizer wants to do. This would apply to most questions about "is there a performance difference between ...". Of course there are a lot of other tools also, but explain plan is a good start.
It **should** be the same.

Good database engine will generate same plan for that expression.