Skip to main content

SQL Server Related Query

HOW TO MODIFY A COLUMN SIZE, IF WE HAVE MULTIPLE TABLES WITH DIFFERENT SUFFIX AND THAY ALL CONTAINS SAME COLUMN DEFINITIONS, I NEED TO MODIFY A SPECIFIC COLUMN'S SIZE OF ALL TABLES USING ONE SCRIPT. 


AS LIKE MENTIONED BELOW:

UPDATE 

INFORMATION_SCHEMA.COLUMNS

SET 

CHARACTER_MAXIMUM_LENGTH = 100,

CHARACTER_OCTET_LENGTH = 100

WHERE 

TABLE_NAME LIKE '__MYTABLENAME'

AND 

COLUMN_NAME = 'MYCOLUMNNAME'

AND 

CHARACTER_MAXIMUM_LENGTH < 100

----------------------------------------------------------------------------------------------------------------------------------

Using OPENROWSET to read large files into SQL Server


Problem
OPENROWSET is a T-SQL function that allows for reading data from many sources including using the SQL Server's BULK import capability. One of the useful features of the BULK provider is its ability to read individual files from the file system into SQL Server, such as loading a data from a text file or a Word document into a SQL Server table. This capability is the subject of this tip.
Solution
The BULK option was added to T-SQL in SQL Server 2005 and it persists in SQL Server 2008. When using SQL Server 2000 it was possible to read and write to the file system using the sp_OA_Create and sp_OA_Method extended stored procedures. These XPs continue to work, but are disabled by default because of security concerns and it is a better practice to use more secure capabilities like OPENROWSET when they are available.
When used with the BULK provider keyword you can name a data file to read as one of three types of objects:
  • SINGLE_BLOB, which reads a file as varbinary(max)
  • SINGLE_CLOB, which reads a file as varchar(max)
  • SINGLE_NCLOB, which reads a file as nvarchar(max)
OPENROWSET returns a single column, named BulkColumn, as its result. Here's an example that reads a text file:
SELECT BulkColumn 
FROM OPENROWSET (BULK 'c:\temp\mytxtfile.txt', SINGLE_CLOB) MyFile
The correlation name, in this case MyFile, is required by OPENROWSET.
There are additional requirements when reading single files that must also be observed as mentioned below.
Access control is always a concern. The operating system level file operations to read the file are executed with the privileges of the account that the SQL Server data engine is using. Therefore, only files accessible to that account may be read. This includes network drives or UNC paths, which are permitted if the account has the privileges. If you want to read network files, run SQL Server as a domain user.
The BULK provider won't convert between Unicode and plain ASCII files. It must be told which type of encoding is used in the file. If you don't the result is error 4806 as seen here:
SELECT BulkColumn 
FROM OPENROWSET (BULK 'c:\temp\SampleUnicode.txt', SINGLE_CLOB) MyFile
Msg 4806, Level 16, State 1, Line 1
SINGLE_CLOB requires a double-byte character set (DBCS) (char) input file. The file specified is Unicode.
Unicode files must be read with the SINGLE_NCLOB option shown here:
SELECT BulkColumn 
FROM OPENROWSET (BULK 'c:\temp\SampleUnicode.txt', SINGLE_NCLOB) MyFile
Similarly, files with non text structures, such as Word documents are not converted. They must be converted by some other mechanism before being read or they can be read as binary files with the SINGLE_BLOB option.
OPENROWSET isn't flexible about how you provide the name of the file. It must be a string constant. That requirement forces the use of dynamic SQL when the file name isn't known in advance.
Here's a stored procedure that reads any text file and returns the contents as an output variable:
SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO 
CREATE PROC [dbo].[ns_txt_file_read]  
    
@os_file_name NVARCHAR(256
   ,
@text_file VARCHAR(MAXOUTPUT  /* Reads a text file into @text_file 

* Transactions: may be in a transaction but is not affected 
* by the transaction. 

* Error Handling: Errors are not trapped and are thrown to 
* the caller. 

* Example: 
    declare @t varchar(max) 
    exec ns_txt_file_read 'c:\temp\SampleTextDoc.txt', @t output 
    select @t as [SampleTextDoc.txt] 

* History: 
* WHEN       WHO        WHAT 
* ---------- ---------- --------------------------------------- 
* 2007-02-06 anovick    Initial coding 
**************************************************************/  
AS  
DECLARE 
@sql NVARCHAR(MAX
      , 
@parmsdeclare NVARCHAR(4000)  
SET NOCOUNT ON  

SET 
@sql 'select @text_file=(select * from openrowset ( 
           bulk ''' 
@os_file_name ''' 
           ,SINGLE_CLOB) x 
           )' 
SET @parmsdeclare '@text_file varchar(max) OUTPUT'  
EXEC sp_executesql @stmt @sql 
                 
@params @parmsdeclare 
                 
@text_file @text_file OUTPUT 
To see how it works, just execute the example script:   First create a text file called "SampleTextDoc.txt" and add some text data to the file.  For our example we added the following text "The quick brown fox jumped over the lazy dog.".
DECLARE @t VARCHAR(MAXEXEC ns_txt_file_read 'c:\temp\SampleTextDoc.txt'@t output SELECT @t AS [SampleTextDoc.txt] 
The results are:
SampleTextDoc.txt
The quick brown fox jumped over the lazy dog.
(1 row(s) affected)
The performance of reading text files is remarkably fast because the files are read sequentially. Using a 64 bit SQL Server 2008 on a development machine, reading a file of 750,000,000 bytes took only 7 seconds.

Comments

Popular posts from this blog

How to find and remove duplicate files from PC uplicate files can cause all kinds of problems on your computer, taking up precious storage room, confusing your photo or media manager apps, and generally getting in the way of searches and other operations when you'd rather they didn't. You don't have to accept duplicate files as an inevitability of running a PC, though: Here's how to get rid of them. Duplicate files can crop up for all kinds of reasons: Maybe you downloaded a file, forgot it was there, and then downloaded it again; maybe you copied a folder of images and then never got around to getting rid of the originals. Whatever the reason, they clog up your disk space and shouldn't be left to gather dust. For the purposes of this guide we're going to use DupeGuru-it's Lifehacker's pick as the best duplicate file finder for Windows, and it's available for Mac and Linux as well. If you're not taken with DupeGuru, then some of the best al...

Gmail Automation

Gmail Automation: 5 Useful Google Scripts to Automate Your Gmail 1. Auto delete emails after X number of days Very often, after we read the email, we will just keep it in our inbox, regardless whether it is useful or not. While Google gives you tons of space to store your emails, you might still want to clean up your inbox and get rid of those useless emails. The following script can check emails with the “Delete Me” label and delete them after “x” number of days. 1. Go to  Google Scripts  and create a blank project (make sure you are logged into your Google account). Paste the following script and save it. function auto_delete_mails ( ) { var label = GmailApp.getUserLabelByName ( "Delete Me" ) ; if ( label == null ) { GmailApp.createLabel ( 'Delete Me' ) ; } else { var delayDays = 2 // Enter # of days before messages are moved to trash var maxDate = new Date ( ) ; maxDate.setDate ( maxDate.getDate ( ) -delay...

iPhone 7 and iPhone 7 Plus review: The best iPhones Apple has made

iPhone 7 and iPhone 7 Plus review: The best iPhones Apple has made 's tough meeting expectations years after year. And yet, Apple keeps doing it, although no longer as effortlessly as it would do earlier in this decade. The company launched the iPhone 7 and the iPhone 7 Plus on October 7 in the Indian market, a month after the global announcement of the two phones. These are the phones that look like incremental update to the iPhone 6S and the iPhone 6S Plus. But looks can be deceiving. And they surely are in this case. Of late, the iPhone is facing tough challenge from others in the market. The Galaxy S7 arguably has a better design. The Samsung phone also has better screen and, in most cases, better camera. Google's Nexus phones have better software. The HTC offers better sound in its high-end phones. The Sony phones are waterproof. All of this puts the iPhone at a back-foot. The good thing is that Apple knows these challenges and is meeting them head-on with t...