In the late 1990s I learned MySQL and Java at approximately the same time. How did I teach myself? For MySQL I read the online MySQL manual cover to cover. For Java it was the Java Language Specification or Java Programming Language book, again cover to cover. Then for record I read Effective Java, and I was totally lost. I read it three or four years later and then it made sense.
At that time, with MySQL 3.22/3.23 the scope of the product was smaller, so was Java 1.2. I am confident I have forgotten as much as I retain, however it does marvel me when sometimes the most simplest of functionality I do not recall, or perhaps never learned. Today’s What Did I Learn This Week.
In MySQL, there is a TRIM() function, as the name suggests it trims whitespace, or so I thought. It actually does a lot more as the current MySQL 8.0 manual page states.
You can for example, trim the white space just LEADING, or just TRAILING, and in fact you can trim any pattern of characters, LEADING, TRAILING or BOTH. I just did not know that.
(from the man page)
mysql> SELECT TRIM(' bar ');
-> 'bar'
mysql> SELECT TRIM(LEADING 'x' FROM 'xxxbarxxx');
-> 'barxxx'
mysql> SELECT TRIM(BOTH 'x' FROM 'xxxbarxxx');
-> 'bar'
mysql> SELECT TRIM(TRAILING 'xyz' FROM 'barxxyz');
-> 'barx'
For the record, the products are both widely used more than 20 years after I first started. MySQL has gone from 3.22 to 3.23, 4.0, 4.1, 5.0, 5.1 (the defunct 5.4 and even a 6.0 I think), 5.5, 5.6, 5.7 and now 8.0. Java was SE 1.2, then 1.3, 1.4, 5.0, 6, 7, 8 (my last major version), 9, 10, 11, 12, 13, 14, 15 and now 16, with 17 in the books.
I guess it’s never to late to re-read the manual.