Yugabyte-db: [docs] Document supported YSQL string functions

[rkarthik007]

Below is a list, we should document the ones we support:

ASCII
CONCAT
CHR
FORMAT
LEFT
LENGTH
LPAD
MD5
POSITION
REGEXP_MATCHES
REGEXP_REPLACE
RIGHT
REPLACE
SPLIT_PART
SUBSTRING
TRANSLATE
TRIM
TO_CHAR
TO_NUMBER

[mrpanda]

@rkarthik007 Do you want a "strings" page like I did for Date & Time ?

[kmuthukk]

@mrpanda --

we would totally appreciate that. Thanks for asking!

regards,
Kannan

[rkarthik007]

Yes please @mrpanda!

[mrpanda]

OK, I will have time next week. Can you let me know where the page is going so I can understand what is required, and apart from the list you have above, what focus do you want me to take, I am assuming functions, methods, differences to pg and techniques via examples.

[rkarthik007]

Wonderful! Thank you so much!

There are two places we need to add content (please feel free to choose either one or both!):

• User tutorial which is similar to the date-time one you had written. This goes here: https://docs.yugabyte.com/latest/develop/learn/
  We could create a new section called Working With Strings or some such, and this will be mostly a user tutorial.
• Reference guide for these functions, that will go here: https://docs.yugabyte.com/latest/api/ysql/
  If you look at the left nav, there are some groups that already exist (Commands, Datatypes, etc). We could add a new one called Built-in Functions and add this list there. Please take a look at other entries in the reference for an idea. For example: https://docs.yugabyte.com/latest/api/ysql/commands/ddl_create_table/
  We can start without a railroad diagram/syntax grammar, @m-iancu can help you with that.

[mrpanda]

OK, I am starting the User Tutorial now -- as for the Reference Guide, let me ponder that this week.

[mrpanda]

Pull request created for User Tutorial under develop/learn. I didn't find any issues with any of the commands, they all seem to work fine in YB. I don't think I will have time for a Reference Guide, its a lot of work creating documentation !

[rkarthik007]

Thanks for the great content @mrpanda! Agree about the reference docs, no worries at all. @stevebang is taking a look at your PR.