Added wrapper for UPPER() and LOWER() functions for CHAR and NCHAR to handle padding for shorter strings

[Anikait143]

Description

1. Issues

• UPPER() and LOWER() functions for CHAR or NCHAR types compared to a string shorter than definition cause condition to fail.
• String functions do not handle chinese characters for NVARCHAR type when collation is not used in UPPER() and LOWER() functions

2. Changes made to fix the issues

• Added wrapper function handling for UPPER() and LOWER() functions to handle CHAR and NCHAR as VARCHAR and NVARCHAR respectively.

# Input
DECLARE @class NCHAR(2) = N'H'
SELECT '[' + @class + ']' WHERE upper(@class) = N'H'
SELECT '[' + @class + ']' WHERE lower(@class) = N'h'

# previous output (wrong output)               
--------------------

(0 rows affected)

# current output (correct output)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[H ]                                                                                                                                                                                                                                                            

(1 rows affected)

# previous output (wrong output)
1> declare @string1 nvarchar(30) = N'比尔·拉';
2> select UPPER(@string1)
3> GO
@string1                      
------------------------------
??·?  

# current output (correct output)
1> declare @string1 nvarchar(30) = N'比尔·拉';
2> select UPPER(@string1)
3> GO
@string1                      
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
比尔·拉

• Added Test Cases for these issues

Task: BABEL- 3395 Authored-by: Anikait Agrawal [email protected] Signed-off-by: Anikait Agrawal [email protected]

Test Scenarios Covered

• Use case based - BABEL-3395-vu-*

• Boundary conditions -

• Arbitrary inputs -

• Negative test cases -

• Minor version upgrade tests -

• Major version upgrade tests -

• Performance tests -

• Tooling impact -

• Memory tests -

• Client tests -

Check List

• [x] Commits are signed per the DCO using --signoff

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[coveralls]

Pull Request Test Coverage Report for Build 8637308639

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.005%) to 72.568%

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Totals
Change from base Build 8633276413:	0.005%
Covered Lines:	41152
Relevant Lines:	56708

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💛 - Coveralls

[Anikait143]

Have we verified with other datatypes whether it is hitting the newer version of the function or the older PG one?

1> DECLARE @smalldatetime smalldatetime = '1955-12-13 12:43:10';
2> select CAST(@smalldatetime AS varchar)
3> go

Right missed it earlier, I have now added handling and tests with all other datatypes as well for the newer function definition

[rohit01010]

Kindly add newly created test BABEL-3395 in schedule files of upgrades