将 Image 数据类型转换为 Base64，将 Base64 转换为 Image 数据类型

Question

I'm using Data-Type "Image" in MS SQL 2012 to store Image.

problem: I have an image in BASE64 string in C#

/9j/4AAQSkZJRgABAQEASABIAAD/4SKhRXhpZgAATU0AKgAAAAgABwESAAMAAAABAAEAAAEaAAUAAAABAAAAYgEbAAUAAAABAAAAagEoAAMAAAABAAIAAAExAAIAAAAeAAAAcgEyAAIAAAAUAAAAkIdpAAQAAAABAAAApAAAANAALcbAAAAnEAAtxsAAACcQQWRvYmUgUGhvdG9zaG9wIENTNiAoV2luZG93cykAMjAxNjowMjowNSAxNDo1MTo0MwAAA6ABAAMAAAABAAEAAKACAAQAAAABAAAFUKADAAQAAAABAAACWAAAAAAAAAAGAQMAAwAAAAEABgAAARoABQAAAAEAAAEeARsABQAAAAEAAAEmASgAAwAAAAEAAgAAAgEABAAAAAEAAAEuAgIABAAAAAEAACFrAAAAAAAAAEgAAAABAAAASAAAAAH/2

I am converting it into byte[] in C# as I need to save it into a column of data type IMAGE. Like this:

byte[] imageInByteArray =Convert.FromBase64String("MyImage");

It is saved successfully like this:

The byte[] array data in database -

Now I am trying to retrieve an image and converting it back into BASE64 using this:

var imageA = results.Read<byte[]>().ToArray();
string imageB =Convert.ToBase64String(imageA);

Now I am getting the result like this:

MHhGRkQ4RkZFMTAwNTg0NTc4Njk2NjAwMDA0RDREMDAyQTAwMDAwMDA4MDAwNDg3NjkwMDA0MDAwMDAwMDEwMDAwMDAzRTAxMTIw

The result is not what I was expecting it should be like this

/9j/4AAQSkZJRgABAQEASABIAAD/4SKhRXhpZgAATU0AKgAAAAgABwESAAMAAAABAAEAAAEaAAUAAAABAAAAYgEbAAUAAAABAAAAagEoAAMAAAABAAIAAAExAAIAAAAeAAAAcgEyAAIAAAAUAAAAkIdpAAQAAAABAAAApAAAANAALcbAAAAnEAAtxsAAACcQQWRvYmUgUGhvdG9zaG9wIENTNiAoV2luZG93cykAMjAxNjowMjowNSAxNDo1MTo0MwAAA6ABAAMAAAABAAEAAKACAAQAAAABAAAFUKADAAQAAAABAAACWAAAAAAAAAAGAQMAAwAAAAEABgAAARoABQAAAAEAAAEeARsABQAAAAEAAAEmASgAAwAAAAEAAgAAAgEABAAAAAEAAAEuAgIABAAAAAEAACFrAAAAAAAAAEgAAAABAAAASAAAAAH/2

Answer 1

I found the solution for this, Please look into this because it might be useful when you do not want to change your datatype Image in your database:

I sent base64 string as it is to database and there I converted it into varbinary like this:

SELECT CAST(N'' AS xml).value('xs:base64Binary(sql:variable("@Image2"))', 'varbinary(max)')

and inserted it into the image column.

then I retrieved an image in base64 like this:

 SELECT cast('' as xml).value('xs:base64Binary(sql:column("img"))', 'varchar(max)') FROM imageTemp WHERE...

It gave me the exact Base64 string which I have sent earlier.

Thank You.

Answer 2

I believe you need help on how to store image data in sql server.

You can create a table like below. Please note that you may not want to create database , just a table would suffice. If you already have a table where you want to save this data, you will have to make sure that the type of column is varbinary(max).

CREATE DATABASE MyDatabase;  
GO  
USE MyDatabase;  
GO  
CREATE TABLE MyImageDatabaseTable (Id int, BLOBData varbinary(max));  
GO  

Then you can read the data as:

SqlConnection objConn = new SqlConnection(connectionString);  
objConn.Open();  
SqlCommand objCmd = new SqlCommand("Select * From MyImageDatabaseTable", objConn);  
SqlDataReader dr = objCmd.ExecuteReader();  
while(dr.Read())
{
     byte[] myImageByteArrayData = (byte[]) dr["BLOBData"];  

     string myImageBase64StringData = Convert.ToBase64String(myImageByteArrayData );
}

Hope this helps.

Answer 3

Answering your question

How to retrieve base64 from database using this byte[] array?

SQL-Server will transform your binary to base64 implicitly when embedding it into XML.

Try this

--I fill a binary variable with some dummy content
DECLARE @SomeBinary VARBINARY(MAX) = CAST('This is a dummy content' AS VARBINARY(MAX));
--this is the resulting binary
SELECT @SomeBinary;
--Now you see what happens using FOR XML PATH
SELECT (SELECT @SomeBinary FOR XML PATH(''))

We can re-convert this easily

DECLARE @base64 VARCHAR(MAX)='VGhpcyBpcyBhIGR1bW15IGNvbnRlbnQ=';
SELECT CAST(@base64  AS XML).value('.','varbinary(max)');

Probably you'll have to use a CAST(YourImageTypedColumn AS VARBINARY(MAX)) first.

But it might be easier to retrieve this as binary and to the conversion on your client side application.

Answer 4

I use this method bellow, to convert bytearray from database to an image.

public Bitmap ConvertByteArrayToBitmap(byte[] Array)
{
    if (Array == null) return null;

    using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
    {
        ms.Write(Array, 0, Array.Length);
        ms.Position = 0L;

        return new Bitmap(ms);
    }
}

Regards.

Answer 5

You can Convert binary to Base64 using XML and the hint "for xml path"

select file_name,ColumnWithBinary,ColumnToSwFinalResult
from TableWithBinary
cross apply (select ColumnWithBinary '*' for xml path('')) T (ColumnToSwFinalResult)
GO

Answer 6

I got it!!!

C# code

string base64Encoded = Convert.ToBase64String(((byte[])result.photoFromSQLImageColumn));
string base64Decoded;
byte[] data = System.Convert.FromBase64String(base64Encoded);
base64Decoded = System.Text.ASCIIEncoding.ASCII.GetString(data);

and in this variable -----> base64Decoded you will have your rigth base64 string!!

Greetings from México!!!