SUBSTR BETWEEN in Teradata

Question

Output of the following SQL statement is '279A'

    SELECT
    SUBSTR('H0279A',3)

I am confused why this query returns 1:

        SELECT 
        CASE 
            WHEN SUBSTR('H0279A',3) BETWEEN '0000' AND '9999'   
            THEN 1
        ELSE 0
        END

How can '279A' be between '0000' AND '9999' ? I am using Teradata.

Answer 1

Your H0279A is of type varchar. And so is 0000 and 9999. So essentially you are comparing strings and not numbers. 2 comes after 0 and before 9. So its no wonder that 279A is between 0000 and 9999.

Do you want to check whether the given string is between 0 and 9999. Then you should do this.

SELECT 
    CASE 
        WHEN SUBSTR('H0279A',3) BETWEEN 0 AND 9999   --here 0 and 9999 are numbers, not strings
           THEN 1
    ELSE 0
    END;

But this will raise exception, since conversion of 279A to number fails.

UPDATE: Lets keep aside SUBSTR for a while.

create table ntest(
    col1 varchar(20)
    );

insert into ntest values('abs');
insert into ntest values('abscond');
insert into ntest values('000');
insert into ntest values('000000A');
insert into ntest values('9999');
insert into ntest values('027A');
insert into ntest values('zip');
insert into ntest values('279');
insert into ntest values('279A');
insert into ntest values('877');

select * from ntest order by col1;

col1
-------------------- 
000              <--------------------------¬
000000A                                      |
027A                                         |
279                                          |
279A   -- strings starting with 2 are between strings starting with 0 and 9
877                                          |
9999             <--------------------------⤶
abs
abscond
zip