1. Jan Engelsberg Program Manager, SQL Server
DBI308
Practical Uses and Optimization of New T-SQL Features in Microsoft SQL Server 2012
Jan Engelsberg
Program Manager, SQL Server
© 2007 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

2. Program Manager, SQL Server
Jan
Engelsberg

3. Agenda Key generation Exceptions & Messages
Calculations & Aggregations
Common tasks

4. Key generation Use cases: Options:
Unique keys across multiple tables Customers & Employees  Contacts
Client-side/distributed-system key generation Prep files with related items for import
Options:
GUIDs
Table to manage the keys
NEW: Sequences
Key generation
SQL Server 2012

5. Sequence Generators
CREATE SEQUENCE [ schema_name . ] sequence_name
[ AS { <built_in_integer_type> | <user-defined_integer_type> } ]
[ START WITH <constant> ]
[ INCREMENT BY <constant> ]
[ MINVALUE <constant> | NO MINVALUE ]
[ MAXVALUE <constant> | NO MAXVALUE ]
[ CYCLE | NO CYCLE ]
[ CACHE [ <constant> ] | NO CACHE ]
NEXT VALUE FOR
[ schema_name . ] sequence_name
[ OVER (<over_order_by_clause>) ]
EXEC sp_sequence_get_range …
New Database Object, similar to the IDENTITY property
Separates number-generation from table/column
ANSI SQL standard compliant implementation

6. Key generation in action

7. GUIDs Pros Cons Separate table Sequences
Guaranteed to be globally unique
Can be made sequential
Caveats!
Cannot be guessed (when not sequential)
Use any data type for keys (for ex. strings)
Can guarantee a continuous range of values (no wholes)
Including ranges
Serializes number generation across transactions
Supports all integer types, starting from TINYINT up to DECIMAL(38, 0)
Supports range reservation
Caching “knob” for performance tuning
Large; requires 16 bytes storage
Many systems don’t natively support GUIDs
Causes fragmentation
Sequential generation cannot be guaranteed even with NEWSEQUENTIALID()
Access to the identifier is serialized across transactions
Performance issue
Not native RDBMS functionality, more code
Cannot guarantee a continuous range of values
E.g. can “lose” values because of dirty shutdowns or rollbacks

8. Exceptions & Messages Use cases: Options:
Send progress updates to the application
Log events
Raise & handle exceptions
Options:
RAISERROR
xp_logevent
Logging table
NEW: THROW
Exceptions & Messages
SQL Server 2012

9. New error handling with THROW
THROW <number>, <message>, <state>;
Always aborts the batch
Batch aborts if not in SET XACT_ABORT ON where it transaction-aborts
Does not automatically use sys.messages
Is even spelled correctly!
re-THROW
BEGIN CATCH …; THROW; END CATCH

10. Exceptions & messages in action

11. RAISERROR THROW xp_logevent Logging table Pros Cons Flexible
Well known
Easy to use
Similar behavior to other programming languages
Re-throw capabilities
Logs events without sending a message to the client
Flexible, supports the attributes you specify
Cons
Multiple behaviors, easy to get it wrong
Less flexible than RAISERROR
Not supported on SQL Azure
Transactions need to be managed so log records are not rolled back

12. Calculations & Aggregations
Use cases:
Include aggregations in details Cumulative sum, averages etc.
Reference other rows in a calculation Finding gaps, trends, etc.
Options:
Imperative programming patterns
Correlated sub queries
NEW: Window Functions
SQL Server 2012
Calculations & Aggregations

13. Calculations across rows
Referencing same row is simple:
Transaction cost is $1.5/tran., what was the total amount?
Amount AS TotalAmount
What about other rows?
Current bank balance?
Current account balance?
Number of days since last tran.?
Amount of previous transaction?
TranId
AccountId
TranDate
Amount 1
120 2
500 3
430 4 95 5 50 6 25 7
250 8 9
5000 10 75

14. Window Functions
Calculate the average amount of the last 3 transactions
TranId
AccountId
TranDate
Amount 1
120 2
500 3
430 4 95 5 50 6 25 7
250 8 9
5000 10 75
3 trn. avg.
Window FRAME
The FRAME
The FRAME
The FRAME
The FRAME
The FRAME
The FRAME
The FRAME
Window PARTITION
56.666

15. Window Functions
Multiple partitions, e.g. for calculating the balance for different accounts
TranId
AccountId
TranDate
Amount 1
120 4 95 7
250 10 75 13
125 16
175 2
500 5 50 8 25 11
Balance
120
215
465
540
Window FRAME
Window FRAME
Window PARTITIONs
665
840
500
550
575
700

16. Window Functions Aggregation Analytical Distribution Offset
AVG, CHECKSUM_AGG, COUNT, COUNT_BIG, MIN, MAX, SUM, STDEV, STDEVP, VAR, VARP
User-defined CLR Aggregates (excl. windowing)
Analytical
ROW_NUMBER, NTILE, RANK, DENSE_RANK, CUME_DIST, PERCENT_RANK
Distribution
PERCENTILE_CONT, PERCENTILE_DISC
Offset
LAG, LEAD, FIRST_VALUE, LAST_VALUE

17. Calculations & Aggregations in action

18. Correlated sub queries Window Functions
Imperative approach
Pros
Cons
Correlated sub queries
Window Functions
Approach that is commonly used in other programming languages
Follows the SQL set based paradigm
Improved optimization
Easy to write
Following the SQL set based paradigm
Not set based
Only individual queries are optimized, not the operation as a whole
Many lines of code  Higher risk for bugs
Bad performance due to plan with N2 complexity solution
Non-trivial to write
Not always the optimal solution
Not all queries can be easily rewritten to leverage window functions

19. Common tasks Use cases: Options: Transform data to and from strings
Constructing date instances
Handle conversion errors
Paging
Options:
Write yourself
NEW: Additional scalar functions
SQL Server 2012
Common tasks

20. New Scalar Functions New conversion functions for all types:
TRY_CONVERT(data_type[(length)], expression [,style])
TRY_CAST(expression AS data_type[(length)])
New conversion functions to and from strings:
FORMAT(value, format [,culture])
PARSE(string_value AS data_type [USING culture])
TRY_PARSE(string_value AS data_type [USING culture])
Other functions:
IIF(boolean_expr, true_value, false_value)
CHOOSE(index, val1, val2,... [,valN])
CONCAT(val1, val2,… [,val N])

21. New Scalar Functions New date & time related functions:
EOMONTH(date [, months_to_add])
DATEFROMPARTS(year, month, day)
TIMEFROMPARTS(hour, minutes, seconds, fractions, scale)
DATETIME2FROMPARTS(year, month, day ,hour, minutes, seconds, fractions, scale)
DATETIMEFROMPARTS(year, month, day, hour, minutes, seconds, milliseconds)
SMALLDATETIMEFROMPARTS(year, month, day, hour, minutes)
DATETIMEOFFSETFROMPARTS (year, month, day, hour, minute, seconds, fractions, hour_offset, minute_offset, precision)

22. Query Constructs / Dynamic SQL enhancements
OFFSET / FETCH
Support for paging result sets
Enforce contract for Result Sets for EXEC
SELECT ...
ORDER BY ...
OFFSET <expr> ROWS FETCH NEXT <expr> ROWS ONLY
EXECUTE <proc|clr proc|remote proc|function> [WITH <execute_option>[,...n ]]
{ RESULT SETS {UNDEFINED|NONE|(<result_sets_definition>)} }
<result_sets_definition> ::=
{ <result_set_definition>
| AS OBJECT [<object_location>.] {table_name | view_name | tvf} | AS TYPE [schema_name.]table_type_name
| AS FOR XML | (…) [,...n ]}

23. Common tasks in action

24. Questions ?

25. Related Content
(DBI311) Microsoft SQL Server Data Tools: Database Development from Zero to Sixty
(DBI409)SQL Server Columnstore Performance Tuning
(DBI21-HOL ) What's New in T-SQL for Microsoft SQL Server 2012
(DBI31-HOL) Getting Started with SQL Server Data Tools in Microsoft SQL Server 2012
(DBI07-TLC ) Microsoft SQL Server: Cloud on Your Terms - Optimized Productivity
Find me in the TLC area at: 7:30 to 9p, Tuesday 10:30a to 1p, Wednesday 12:30 to 3:30p

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30. 11/24/ :06 AM
© 2012 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.
© 2009 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

31. 11/24/ :06 AM
© 2009 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.