比较SQL Server中的日期

Question

I building an ASP.NET application that connects to SQL Server 2008 R2. I having a brain fart on this one. I am trying to get some records between a date that the user chooses.

The application builds a sql statement and sends it to the server and waits for a return of records. The SQL statement looks like this.

SELECT * From policy pp where 20160115 between pp.policy_begin_date and pp.policy_end_date

It returns all records.

Do I need to convert '20160115' to a datetime variable? If so how do I convert that?

Answer 1

Yes. Like this:

... WHERE CAST('2016-01-15' AS DATE) BETWEEN ...

Unless it's really a datetime.

Answer 2

SELECT * 
From policy pp 
where cast('20160115' as datetime) between pp.policy_begin_date and pp.policy_end_date

You can use CAST or CONVERT

Answer 3

You SHOULD cast/convert your string to date, because it is depending on the language of the server if it works.

Best way is to use convert and give information about language:

convert(date[time], '20160115', 112)