Out of Memory exception while converting byte array into string

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C#

Hi,
I'm getting out of memory exception while converting byte array into a string. Initially I've stored content of a file(338 MB) into DataBase in varbinay format , after reading the content from DataBase I'm conveting that Byte array into string wher I'm getting the error .

var val = cmd.ExecuteScalar();//Getting form DataBase
System.Text.Encoding enc = System.Text.Encoding.ASCII;
string myString = enc.GetString((byte[])val);//Converting into String

Please someone tell me a solution.

Thanks & Regards,
Ramana