PostgreSQL has a bunch of string functions, including several for doing various string trimming.
We can use the simplest form of trim to remove leading and trailing space
characters from a string.
> select trim(' Taco Cat ');
+----------+
| btrim |
|----------|
| Taco Cat |
+----------+The syntax for calling trim is a bit odd relative to other PostgreSQL
functions and functions in other languages. Here is the "grammar" as described
in the docs:
trim ( [ LEADING | TRAILING | BOTH ] [ characters text ] FROM string text ) → text
We pick leading, trailing, or both, with both being the default. Then
we specify the character(s) we want to remove. This is also optional, the
default being the space character. Then we say from what string we want to
trim those characters.
Here we remove all sequential spaces from both ends of the given string:
> select trim(both from ' Taco Cat ');
+----------+
| btrim |
|----------|
| Taco Cat |
+----------+To further demonstrate how trim works, here we remove all sequences made up
of any of spaces, uppercase T, and lowercase t from both ends of the
string:
> select trim(both ' Tt' from ' Taco Cat ');
+--------+
| btrim |
|--------|
| aco Ca |
+--------+Notice that in all the above examples the column name of the result is btrim.
That's probably because btrim (trim both ends) is being called under the
hood for the both option.