问题
I want to make a search using "between" clause over a string column. Doing some test I got this:
Let's assume that there is a country table with a "name" column of type varchar. If I execute this query:
Select * from country where name between 'a' and 'b'
I got this result:
Argentina
.
.
.
Argelia.
It excludes those countries that starts with B which I found a little bit weird.
Is there a way to do this search in a more accurate way? Any other ideas for make this search?
Thanks in advance
回答1:
The expression
name between 'A' and 'B'
is equivalent to
name>='A' and name<='B'
So 'Argentina' is >='A' and <='B' and it satisfies the condition. But 'Bolivia' is NOT <='B'. 'Bolivia'>'B'. It doesn't just look at the first letter: it looks at the whole string. Which is surely the way it ought to be: if it didn't do this, there'd be no way to say that you wanted a range that included 'Smith' but not 'Smithers'.
To accomplish what you want, you could say:
substr(name,1,1) between 'A' and 'B'
or:
name like 'A%' or name like 'B%'
or:
name>='A' and name<'C'
回答2:
i think i know how to solve your problem. u can try adding extra character in the back like this
select * from tablea where column1 between 'ABC' and 'ACD'+'Z'
this will return a result from ABC% to ACE
回答3:
Another query that would get countries that start with b as well as A, would be:
Select * from country where name between 'a' and 'c'
回答4:
The result's accurate, but you may be misunderstanding. x between a and b means x>=a and x<=b. (See the PostGRES documentation for details.)
If you want to get lines that start with either an a or a b, say what you mean:
select * from country where name like 'a%' or name like 'b%'
like uses the table indices so you'll get full performance for using this.
回答5:
Select * from country where substring(name FROM 1 FOR 1) between 'A' and 'B';
回答6:
The reason this statement didn't work is SQL pads the string with whitespace until it's the same length as the comparing string. So, in comparison, sql compared b followed by several blanks with b******. Because whitespace appears before all the other letters, sql decided b***** came after b[6 spaces]. So it shouldn't be displayed.
来源：https://stackoverflow.com/questions/5980783/sql-between-clause-with-strings-columns