(With the current release of CTP 2 version you can play with this feature)

A Temporal Data is tightly related to a Time period and used to handle the time-varying data. It provides the ability to look at data trends, types of data changes, and the overall data evolution within your database.

A Temporal Table is a table for which a PERIOD definition exists and which contains system columns with a datatype of datetime2 into which the period of validity is recorded by the system, and which has an associated History Table into which the system records all prior versions of each record with their period of validity.

>> To maintain Temporal data it require 2 tables:

1. A parent Temporal or System Versioned Table, created by simple CREATE TABLE statements with few more options.

2. A child History Table, automatically created by the above CREATE TABLE statement and further maintained by the SQL DB Engine for all DML operations.

>> DML operations on Temporal Table:

1. The INSERT operation will add a new record in the parent Temporal Table.

2. The UPDATE operation will copy the existing version of the row to the child History Table, and replaces it with new values in the parent Temporal Table.

3. The DELETE operation will copy the existing version of the row to the child History Table, and deleted the existing row in the parent Temporal Table.

4. While reading (SELECT) the rows you've to specify the datetime value and depending on it, it will check the parent Temporal or child History table to fetch the data for you.

>> With Temporal Data support you can do:

1. Time Travel

2. Data Audit

3. maintain Slowly Changing Dimension (SCD)

4. recover from accidental data changes by repairing record-level corruptions (for DBAs).

>> I've talked on working with various option on Temporal Data/Tables with examples on my personal blog below:

1. CREATE a new set of Temporal Tables.

2. Enable Temporal or System Versioning on existing tables with data.

3. View the in-depth Demo.

>> More on Temporal Data/Tables on MSDN BoL: https://msdn.microsoft.com/en-us/library/dn935015.aspx

– With this CTP2 release you can only export data as JSON string.

– But with the release of CTP3 you will also be able to read JSON data by T-SQL query and convert it into tabular (row/column) format, and will support indexes.

–> JSON support is very similar to XML, so you can also:

1. Store JSON data in SQL Server in table columns as NVARCHAR datatype.

2. Export SQL tables rows to JSON data.

3. Query external JSON data and store back in SQL tables.

–> Just like XML for exporting JSON data you can use FOR JSON [AUTO | PATH] syntax:

1. FOR JSON AUTO: option automatically creates a nested JSON data with sub arrays based on the table hierarchy used in the Query. The AUTO option must have a FROM clause.

2. FOR JSON PATH: option enables you to define the structure of output of JSON data using the column names with aliases by using a dot separator.

–> Let’s see how export to JSON works:

– I’ll create a sample table and insert few rows in it:

 CREATE TABLE Students (
 ID INT IDENTITY(1,1) NOT NULL, 
 FirstName VARCHAR(255), 
 LastName VARCHAR(255), 
 Class INT,
 Marks DECIMAL(3,1)
 )
 
 INSERT INTO Students (FirstName, LastName, Class, Marks)
 SELECT 'Manoj', 'Pandey', 10, 80.5
 UNION ALL
 SELECT 'Saurabh', 'Sharma', 11, 82.7
 UNION ALL
 SELECT 'Kanchan', 'Pandey', 10, 90.5

1. Let’s check the “FOR JSON AUTO” option:

 SELECT ID, FirstName, LastName, Class, Marks 
 FROM Students
 FOR JSON AUTO -- here

– Output with AUTO option:

[  
   {  
      "ID":1,
      "FirstName":"Manoj",
      "LastName":"Pandey",
      "Class":10,
      "Marks":80.5
   },
   {  
      "ID":2,
      "FirstName":"Saurabh",
      "LastName":"Sharma",
      "Class":11,
      "Marks":82.7
   },
   {  
      "ID":3,
      "FirstName":"Kanchan",
      "LastName":"Pandey",
      "Class":10,
      "Marks":90.5
   }
]

This option as mentioned previously formats the JSON document automatically based upon the columns provided in the Query.
 

2. Now let’s check the “FOR JSON PATH” option: with this option you can use the dot syntax as used in below Query to form a nested output.

SELECT
 ID,
 FirstName AS "StudentName.FirstName", 
 LastName AS "StudentName.LastName", 
 Marks
 FROM Students
 FOR JSON PATH -- here

– Output with PATH option:

[  
   {  
      "ID":1,
      "StudentName":{  
         "FirstName":"Manoj",
         "LastName":"Pandey"
      },
      "Marks":80.5
   },
   {  
      "ID":2,
      "StudentName":{  
         "FirstName":"Saurabh",
         "LastName":"Sharma"
      },
      "Marks":82.7
   },
   {  
      "ID":3,
      "StudentName":{  
         "FirstName":"Kanchan",
         "LastName":"Pandey"
      },
      "Marks":90.5
   }
]

As you can see with PATH option you can create wrapper objects (here “StudentName”) and nest properties (here “FirstName” & “LastName”).

--> FOR JSON PATH without FROM <table> clause:

 SELECT 
 1 as 'a',
 2 as 'b'
 FOR JSON PATH

– Output without FROM clause:

{
  "a": 1,
  "b": 2
}

--> FOR JSON PATH without FROM clause and with ROOT option:

 SELECT 
 1 as 'a',
 2 as 'b'
 FOR JSON PATH, ROOT('root')

– Output without ROOT option:

{
  "root": {
    "a": 1,
    "b": 2
  }
}

--> As I mentioned above "FOR JSON AUTO without FROM" clause is not supported

 SELECT 
 1 as 'a',
 2 as 'b'
 FOR JSON AUTO

ERROR MESSAGE:

Msg 13600, Level 16, State 1, Line 116
FOR JSON AUTO requires at least one table for generating JSON objects.
Use FOR JSON PATH or add a FROM clause with a table name. 

–> You can also check the demo here:

Source: from my personal blog SQLwithManoj: https://sqlwithmanoj.com/2015/06/01/working-with-json-data-and-sql-queries-sql-server-2016/

In SQL Server 2014 this behavior is unchanged and addition to this you can also create ColumnStore index as a Clustered index. And the good thing is that the table having“Clustered ColumnStore” index can also be updated. However there is one more big limitation here that there is no Clustered Key with this type if index, thus risking the Uniqueness in the table.

–> Here we will see this limitation and a workaround which can be used in some scenarios:

And today I’m very happy to announce the release of my 2nd Windows 8 App for and its availability on Windows 8 store.

With this App you can view and read SQL Server related topics from various sources (like MSDN blogs, MVPs and other famous Bloggers) at one place.

Please download this App on your Windows 8 PC or Tablet and let me know your feedback.

Thanks!!!

Disclaimer: This is my personal Win8 App. The items/blogs expressed here are represented by the respective Blog owners and not from Microsoft. For accuracy and official reference refer to MS Books On Line and/or MSDN/TechNet.

BACKUP DATABASE [AdventureWorks2012] 
TO DISK='E:\FOLDER_NOT_EXISTS\test.bak' 

The above code throws 2 errors with Error-Message IDs 3201 & 3013, as shown below:

Error messages:
Msg 3201, Level 16, State 1, Line 2
Cannot open backup device ‘E:\FOLDER_NOT_EXISTS\test.bak’. Operating system error 3(The system cannot find the path specified.).
Msg 3013, Level 16, State 1, Line 2
BACKUP DATABASE is terminating abnormally.

>> Example #2:
And when you try to use error-handling by using TRY-CATCH and RAISERROR(), it fetches us only 1 error:

BEGIN TRY
BACKUP DATABASE [AdventureWorks2012] 
TO DISK='E:\FOLDER_NOT_EXISTS\test.bak'
END TRY
BEGIN CATCH
DECLARE @msg VARCHAR(1000)
SET @msg = ERROR_MESSAGE()
RAISERROR(@msg,16,0)
END CATCH

Here, only 1 error message will be returned, and the message does not show the actual line where error occurred:

Error messages:
Msg 50000, Level 16, State 0, Line 7
BACKUP DATABASE is terminating abnormally.

>> Example #3:
But this is not the case with the new THROW clause, as I mentioned previously.
It throws all the errors that are originally thrown by the original SQL statement, like below:

BEGIN TRY
BACKUP DATABASE [AdventureWorks2012] 
TO DISK='E:\FOLDER_NOT_EXISTS\test.bak'
END TRY
BEGIN CATCH
THROW;
END CATCH

The above statement throws both the error details as we saw in the first example, and this message show the exact line number where the error occurred:

Error messages:
Msg 3201, Level 16, State 1, Line 2
Cannot open backup device ‘E:\FOLDER_NOT_EXISTS\test.bak’. Operating system error 3(The system cannot find the path specified.).
Msg 3013, Level 16, State 1, Line 2
BACKUP DATABASE is terminating abnormally.

Thus, you must consider using THROW clause instead of the RAISERROR function if you are in SQL Server 2012 and above.

But, it may depend on different conditions and scenarios where you would need either of both the features.

Source: from my personal blog SQLwithManoj: https://sqlwithmanoj.wordpress.com/2013/01/24/another-reason-to-use-throw-clause-instead-of-raiserror-sql-server-2012/

Both RAISERROR & THROW can be used in T-SQL code/script to raise and throw error within a TRY-CATCH block. Check my previous post for TRY-CATCH block, [link].

>> With RAISERROR developers had to use different ERROR_xxxx() system functions to get the error details to pass through the RAISERROR() statement, like:
- ERROR_NUMBER()
- ERROR_MESSAGE()
- ERROR_SEVERITY()
- ERROR_STATE()

let’s see an example:

-- Using RAISERROR()
DECLARE 
 @ERR_MSG AS NVARCHAR(4000)
 ,@ERR_SEV AS SMALLINT
 ,@ERR_STA AS SMALLINT
 
BEGIN TRY
 SELECT 1/0 as DivideByZero
END TRY
BEGIN CATCH
 SELECT @ERR_MSG = ERROR_MESSAGE(),
 @ERR_SEV =ERROR_SEVERITY(),
 @ERR_STA = ERROR_STATE()

 SET @ERR_MSG= 'Error occurred while retrieving the data from database: ' + @ERR_MSG
 
 RAISERROR (@ERR_MSG, @ERR_SEV, @ERR_STA) WITH NOWAIT
END CATCH
GO

Output:
(0 row(s) affected)
Msg 50000, Level 16, State 1, Line 15
Error occurred while retrieving the data from database: Divide by zero error encountered.

The RAISERROR() can take first argument as message_id also instead of the message. But if you want to pass the message_id then it has to be in sys.messages

>> With THROW the benefit is: it is not mandatory to pass any parameter to raise an exception.
Just using the THROW; statement will get the error details and raise it, as shown below:

-- Using THROW - 1
BEGIN TRY
 SELECT 1/0 as DivideByZero
END TRY
BEGIN CATCH
 THROW;
END CATCH
GO

Output:
(0 row(s) affected)
Msg 8134, Level 16, State 1, Line 2
Divide by zero error encountered.

As you see in the Output above, the error message thrown is the default one. But you can also add your customized message, we will see below.

IMP NOTE: Default THROW statement will show the exact line where the exception was occurred, here the line number is 2 (highlighted GREEN above). But RAISERROR() will show the line number where the RAISERROR statement was executed i.e. Line 15 (highlighted YELLOW above) and not the actual exception.

Also passing the message_id won’t require it to be stored in sys.messages, let’s check this:

-- Using THROW - 2
DECLARE 
 @ERR_MSG AS NVARCHAR(4000) 
 ,@ERR_STA AS SMALLINT 
 
BEGIN TRY
 SELECT 1/0 as DivideByZero
END TRY
BEGIN CATCH
 SELECT @ERR_MSG = ERROR_MESSAGE(),
 @ERR_STA = ERROR_STATE()
 
 SET @ERR_MSG= 'Error occurred while retrieving the data from database: ' + @ERR_MSG;
 
 THROW 50001, @ERR_MSG, @ERR_STA;
END CATCH
GO

Output:
(0 row(s) affected)
Msg 50001, Level 16, State 1, Line 14
Error occurred while retrieving the data from database: Divide by zero error encountered.

But if you parameterize the THROW statement as above it will not show the actual position of exception occurrence, and the behavior will be same as RAISERROR(). As with RAISERROR() you've to provide mandatory params, so there is no way to get the actual position of Line where the error occurred.

As per MSBOL following are the difference between RAISERROR & THROW:

NOTE: As per MS BOL for exception handling in new development work THROW must be used instead of RAISERROR.

Source: from my personal blog SQLwithManoj: https://sqlwithmanoj.wordpress.com/2012/12/20/new-throw-statement-in-sql-server-2012-vs-raiserror/

=> So, to validate it I executed following code and found that ISNUMERIC() function also passes these characters as numbers:

SELECT 
 ISNUMERIC('123') as '123'
 ,ISNUMERIC('.') as '.' --Period
 ,ISNUMERIC(',') as ',' --Comma

Function ISNUMERIC() returns "1" when the input expression evaluates to a valid numeric data type; otherwise it returns "0". But the above query will return value "1" for all 3 column values, validating them as numeric values, but that's not correct for last 2 columns.

=> And not only this, ISNUMERIC() function treats few more characters as numeric, like: - (minus), + (plus), $ (dollar), \ (back slash), check this:

SELECT 
 ISNUMERIC('123') as '123'
 ,ISNUMERIC('abc') as 'abc'
 ,ISNUMERIC('-') as '-'
 ,ISNUMERIC('+') as '+'
 ,ISNUMERIC('$') as '$'
 ,ISNUMERIC('.') as '.'
 ,ISNUMERIC(',') as ','
 ,ISNUMERIC('\') as '\'

This will return "0" for second column containing value "abc", and value "1" for rest of the column values.

So, you will need to be very careful while using ISNUMERIC() function and have to consider all these possible validations on your T-SQL logic.

- OR -

Switch to new TRY_PARSE() function introduced in SQL Server 2012.

=> The TRY_PARSE() function returns the result of an expression, translated to the requested Data-Type, or NULL if the Cast fails. Let's check how TRY_PARSE() validates above character values as numeric:

SELECT 
 TRY_PARSE('123' as int) as '123'
 ,TRY_PARSE('abc' as int) as 'abc'
 ,TRY_PARSE('-' as int) as '-'
 ,TRY_PARSE('+' as int) as '+'
 ,TRY_PARSE('$' as int) as '$'
 ,TRY_PARSE('.' as int) as '.'
 ,TRY_PARSE(',' as int) as ','
 ,TRY_PARSE('\' as int) as '\'

So, the above query gives me expected results by validating first column value as numeric and rest as invalid and returns NULL for those.

=> TRY_PARSE() can be used with other NUMERIC & DATETIME data-types for validation, like:

SELECT 
 TRY_PARSE('123' as int) as '123'
 ,TRY_PARSE('123.0' as float) as '123.0'
 ,TRY_PARSE('123.1' as decimal(4,1)) as '123.1'
 ,TRY_PARSE('$123.55' as money) as '$123.55'
 ,TRY_PARSE('2013/09/20' as datetime) as '2013/09/20'
 

... will give expected results :)

Source: from my personal blog SQLwithManoj: https://sqlwithmanoj.wordpress.com/2013/09/20/use-new-try_parse-instead-of-isnumeric-sql-server-2012/

I also talked about how we can use them to store files and retrieve the information from them.

Here, in this post we will see how we can search in the files stored in FileTables using an existing feature i.e. “FullText Search”.

So, let’s check this by an example. I’ll be using the same code from my previous post to create a new Database and Filetables.

Check here for full details.

I also used to blog on my personal bog site i.e. https://sqlwithmanoj.com about SQL Server (TSQL) and I'll start my 1st blog post here by referring to my latest article.

SQL Server 2012 (a.k.a Denali) is yet to be launched and entire Microsoft community is very excited for this event to occur, so am I. There are lot of articles comming up on various forums and blogs about new features and capabilities of SQL Server 2012.

Here I'll discuss about a new feature of SQL Server 2012 that came to my notice and grabbed my attention a few days back, It's called FileTables.

FilesTables is kind of an extention to FILESTREAM introduced with SQL Server 2008 to support files in Windows file system instead of storing them in SQL tables. This new feature brings support for the windows file namespace and compatibality with Windows Apps to the data files stored in SQL Server.

As per MS BOL, FileTable lets an application integrate its storage and data management components, and provides integrated SQL Server services, including: full-text search and semantic search - over unstructured data and metadata. In other words, you can store files and documents in special tables in SQL Server called FileTables, but access them from Windows applications as if they were stored in the file system, without making any changes to your client applications. Or can store directly in Windows file system and can access, query and update the files directly from SQL Server by issuing simple DML statements.

I've posted about this article with more details and a simple example can be viewed here.

This is fine only when you know how many columns you need. But when columns vary according to the query then how could you apply them on your scripts. The only way is to store them in a string variable at runtime and apply them in a dynamic SQL query, shown below.

This problem was also discussed on MSDN’s following link:https://social.msdn.microsoft.com/Forums/en/transactsql/thread/26f86fd6-6d06-4cc5-9723-9ee4685bd48a where I proposed an answer also described below:

USE [tempdb]
GO

-- Create test tables
create table #studMarks (
studId int,
subjekt varchar(20),
marks int
)

-- Insert test data
insert into #studMarks values (1, 'math', 90)
insert into #studMarks values (1, 'science', 80)
insert into #studMarks values (1, 'english', 70)
insert into #studMarks values (1, 'history', 60)

insert into #studMarks values (2, 'math', 80)
insert into #studMarks values (2, 'science', 60)
insert into #studMarks values (2, 'english', 90)
insert into #studMarks values (2, 'history', 70)

-- Static PIVOT
select StudId, [math], [science], [english], [history]
from (select StudId, subjekt, marks
from #StudMarks)p
PIVOT(MAX (marks) FOR subjekt IN ([math], [science], [english], [history])
) AS pvt
ORDER BY StudId

Output:

- Dynamic PIVOT:

-- Lets add one more record on both the tables to check the results
insert into #studMarks values (1, 'economics', 95)
insert into #studMarks values (2, 'economics', 85)

declare @col varchar(1000)
declare @sql varchar(2000)

select @col = COALESCE(@col + ', ','') + QUOTENAME(subjekt)
from (select distinct subjekt as subjekt from #StudMarks) K

--select @col

set @sql = '
select StudId, ' + @col + '
from (select StudId, subjekt, marks
from #StudMarks)p
PIVOT(MAX (marks) FOR subjekt IN ( ' + @col + ' )
) AS pvt
ORDER BY StudId'

-- print @sql

exec (@sql)

Output:

So, whenever any new subject & marks are added in the table against any student the above Dynamic PIVOT statement will take care of it and add a new column for it.

- Final Cleanup

drop table #studMarks

Source: from my personal blog SQLwithManoj: https://sqlwithmanoj.wordpress.com/2011/01/25/dynamic-pivot/