Clarify some things in the latest TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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-_1580 TILs and counting..._
+_1581 TILs and counting..._
 
 See some of the other learning resources I work on:
 - [Ruby Operator Lookup](https://www.visualmode.dev/ruby-operators)
@@ -899,6 +899,7 @@ See some of the other learning resources I work on:
 - [Timestamp Functions](postgres/timestamp-functions.md)
 - [Toggling The Pager In PSQL](postgres/toggling-the-pager-in-psql.md)
 - [Track psql History Separately Per Database](postgres/track-psql-history-separately-per-database.md)
+- [Trim Leading And Trailing Space From String](postgres/trim-leading-and-trailing-space-from-string.md)
 - [Truncate All Rows](postgres/truncate-all-rows.md)
 - [Truncate Tables With Dependents](postgres/truncate-tables-with-dependents.md)
 - [Turning Timing On](postgres/turn-timing-on.md)

postgres/trim-leading-and-trailing-space-from-string.md

@@ -0,0 +1,58 @@
+# Trim Leading And Trailing Space From String
+
+PostgreSQL has a bunch of [string
+functions](https://www.postgresql.org/docs/current/functions-string.html),
+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.
+
+```sql
+> 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:
+
+```sql
+> 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:
+
+```sql
+> 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.