Add support/highlighting for SQL Server 2012-17 T-SQL enhancements

[TaoK]

• T-SQL enhancements:
  • OFFSET and FETCH NEXT/FETCH FIRST paging
  • THROW statement in exception handling
  • new SEQUENCE object
    • Related DDL, eg CREATE SEQUENCE
    • Related DML, eg NEXT VALUE FOR SomeSequence
  • Windowing ROW and RANGE keywords
    • Related PRECEDING/FOLLOWING, UNBOUNDED PRECEDING/UNBOUNDED FOLLOWING and CURRENT ROW specifiers
  • Windowing LAG() and LEAD()
  • Execute... WITH RESULT SETS clause
  • FORCESCAN and FORCESEEK hint keywords
  • String manipulation functions Format() and Concat()
  • Logical functions Iif(), and Choose()
  • Type conversion functions Parse(), Try_Parse(), and Try_Convert()
  • New DateTime functions (EOMonth(), etc)
  • Other new analytical functions
    • Percent_Rank()
    • Cume_Dist()
    • First_Value()
    • Last_Value()

[TaoK]

@alexandermou also mentions, in duplicate issue #115, "iif() grouping() rollup etc"

[TaoK]

@albyrock87 linked, in Issue #179, to official T-SQL language docs!!

https://docs.microsoft.com/en-us/sql/t-sql/language-reference https://docs.microsoft.com/en-us/sql/t-sql/queries/queries https://docs.microsoft.com/en-us/sql/t-sql/statements/statements

[Vortexel]

Also CREATE OR ALTER syntax for SQL Server.