Added relevant function links to See also sections. "Relevant" is based on a general operation, such as: converting the value between types, modifying the contents of the string, taking sections of the string, finding something within the string, generating strings, determine a character value or create a character from a value, etc. The idea is to increase the chances that people can find something helpful that they might not have known the name of.

As much as possible made See also sections consistent with actual functions listed first, then generic function list pages, etc after.

Changed link title encoding where necessary to be consistent such that ( and ) are HTML-encoded as ( and ), respectively (instead of as just parenthesis).

Added STRING_AGG to Aggregate Functions page (new as of SQL Server 2017). It is a valid aggregate function and behaves consistently with the definition on that page as the two tests below show: a) it works in a HAVING clause, and b) it ignores NULLs.

SELECT tmp.[ID], STRING_AGG(tmp.[name], '~')
FROM  (VALUES (1, 'a'), (2, 'gg'), (1, 'b'), (2, 'hh'), (3, 'zzz')) tmp (ID, [name])
GROUP BY tmp.[ID]
HAVING STRING_AGG(tmp.[name], '~') = 'hh~gg';

returns:

2	hh~gg

And:

SELECT tmp.[ID], STRING_AGG(tmp.[name], '~')
FROM  (VALUES (1, 'a'), (2, 'zzz'), (1, 'b'), (2, NULL), (2, 'gg')) tmp (ID, [name])
GROUP BY tmp.[ID];

returns:

1	b~a
2	gg~zzz