Category: SQL

Recently I was in need to analyze Salesforce debug log for one stubborn issue which was very hard to reproduce. Was able to download 1500+ debug logs on my system, however to analyze it, I decided to take help of SQL Server.

Very soon I came into challenge to read all files in a directory and store it back in SQL Server table.

Found very good article here which helped me to come up with below queries. If you need to read more in detail about below T-SQL and stored procedures please navigate to original article. Continue reading “SQL Server – Read all files in directory and store in Table”

I tried many ways to export files or documents saved as binary (Blob) datatypes in SQL Server. However, finally came up with below solution which worked very well. Below script was used to export around 25GB of files stored in SQL Server.

To understand this, lets create a table in Database which will store files from local system into SQL Server as binary / Blob .

CREATE TABLE [dbo].[Document](
	[Doc_Num] [numeric](18, 0) IDENTITY(1,1) NOT NULL,
	[Extension] [varchar](50) NULL,
	[FileName] [varchar](200) NULL,
	[Doc_Content] [varbinary](max) NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

How to Insert Blob into Database

For demo purpose, we will save two files in our table using below queries

INSERT [dbo].[Document] ([Extension] ,[FileName] , [Doc_Content] )
SELECT 'pdf', 'Salesforce Lightning.pdf',[Doc_Data].*
FROM OPENROWSET 
    (BULK 'C:\G2\My POC\Blog\SQL Server\Source\lightning.pdf', SINGLE_BLOB)  [Doc_Data]

INSERT [dbo].[Document] ([Extension] ,[FileName] , [Doc_Content] )
SELECT 'html', 'Progress.html',[Doc_Data].*
FROM OPENROWSET 
    (BULK 'C:\G2\My POC\Blog\SQL Server\Source\Progress.html', SINGLE_BLOB)  [Doc_Data]

If we try to see content in actual table, it will look like

Export Blob From SQL Server and save it as a file

For demo purpose, we want to save documents on local disc. We will use Doc_Num to be created as folder and document will be saved in that folder. To create folders using SQL Server, we will use stored procedure CreateFolder created in this post.
Note : We will create only one folder per document. If multiple nested folder needs to be created then we need to iterate through each folder and call CreateFolder stored procedure for each folder. Its explained in this blog post.

Now time to see actual T-SQL which will iterate through all documents, create folder and save Blob as a file on local disc.

USE [POC]
DECLARE @outPutPath varchar(50) = 'C:\G2\My POC\Blog\SQL Server\Extract Blob'
, @i bigint
, @init int
, @data varbinary(max) 
, @fPath varchar(max)  
, @folderPath  varchar(max) 
 
--Get Data into temp Table variable so that we can iterate over it 
DECLARE @Doctable TABLE (id int identity(1,1), [Doc_Num]  varchar(100) , [FileName]  varchar(100), [Doc_Content] varBinary(max) )
 
INSERT INTO @Doctable([Doc_Num] , [FileName],[Doc_Content])
Select [Doc_Num] , [FileName],[Doc_Content] FROM  [dbo].[Document]
 
--SELECT * FROM @table

SELECT @i = COUNT(1) FROM @Doctable
 
WHILE @i >= 1
BEGIN 

	SELECT 
	 @data = [Doc_Content],
	 @fPath = @outPutPath + '\'+ [Doc_Num] + '\' +[FileName],
	 @folderPath = @outPutPath + '\'+ [Doc_Num]
	FROM @Doctable WHERE id = @i
 
  --Create folder first
  EXEC  [dbo].[CreateFolder]  @folderPath
  
  EXEC sp_OACreate 'ADODB.Stream', @init OUTPUT; -- An instace created
  EXEC sp_OASetProperty @init, 'Type', 1;  
  EXEC sp_OAMethod @init, 'Open'; -- Calling a method
  EXEC sp_OAMethod @init, 'Write', NULL, @data; -- Calling a method
  EXEC sp_OAMethod @init, 'SaveToFile', NULL, @fPath, 2; -- Calling a method
  EXEC sp_OAMethod @init, 'Close'; -- Calling a method
  EXEC sp_OADestroy @init; -- Closed the resources
 
  print 'Document Generated at - '+  @fPath   

--Reset the variables for next use
SELECT @data = NULL  
, @init = NULL
, @fPath = NULL  
, @folderPath = NULL
SET @i -= 1
END

Variable @outPutPath stores root folder path, where folders will be created and Blob content would be exported into it as a file.

Below image shows output in action :