sql server - Query comparing dates in SQL

Question

I have a table with dates that all happened in the month November. I wrote this query

select id,numbers_from,created_date,amount_numbers,SMS_text 
from Test_Table
where 
created_date <= '2013-04-12'

This query should return everything that happened in month 11 (November) because it happened before the date '2013-04-12' (in December)

But it's only returning available dates that happened in days lesser than 04 (2013-04-12)

Could it be that it's only comparing the day part? and not the whole date?

How to fix this?

Created_date is of type date

Date format is by default yyyy-dd-MM

Answer 1

Instead of '2013-04-12' whose meaning depends on the local culture, use '20130412' which is recognized as the culture invariant format.

If you want to compare with December 4^th, you should write '20131204'. If you want to compare with April 12^th, you should write '20130412'.

The article Write International Transact-SQL Statements from SQL Server's documentation explains how to write statements that are culture invariant:

Applications that use other APIs, or Transact-SQL scripts, stored procedures, and triggers, should use the unseparated numeric strings. For example, yyyymmdd as 19980924.

EDIT

Since you are using ADO, the best option is to parameterize the query and pass the date value as a date parameter. This way you avoid the format issue entirely and gain the performance benefits of parameterized queries as well.

UPDATE

To use the the the ISO 8601 format in a literal, all elements must be specified. To quote from the ISO 8601 section of datetime's documentation

To use the ISO 8601 format, you must specify each element in the format. This also includes the T, the colons (:), and the period (.) that are shown in the format.

... the fraction of second component is optional. The time component is specified in the 24-hour format.