Question

I am from non database background. I have created a table with one of the field data type TEXT.

dataF TEXT

INSERTION:

Have inserted three records with the values :

'842-2-4'
'842-2-5'
'842-2-6'

SELECTION:

Tring to get the records based on date now.

... where dateF between '842-2-4' and '842-2-10'

It fails.

Whereas,

... where dateF between '842-2-4' and '842-2-8'

retrieves all the 3 records.

What am i doing wrong ? Why the first statment fails ?

Kindly suggest.

Answer 1

When comparing strings, the values are compared left to right…

As one string is shorter that the other, you are kind of comparing this…

'842-2-4'
'842-2-1'

Well, nothing is >= '842-2-4' AND <= '842-2-1'.

• Because '842-2-1' comes before '842-2-4'.

• And, so, '842-2-10' comes before '842-2-4' too.

• Just as 'Squiggled' comes before 'Squiggly'

• And as 'xxx-y-az' comes before 'xxx-y-z'

To compare as you desire, make sure all your dates are padded with 0‘s.

BETWEEN '0842-02-04' AND '0842-02-10'

But that will only work after you have padded out the values in your table too.

EDIT:

Also, note that this assumes that your format is YYYY-MM-DD. As a string is compared left to right, you must have the highest magnitude values to the left.

(This means that you can’t use YYYY-DD-MM and still have native string comparisons behave as you would want them.)