BLOB Reading Example (C#)

TEST.SQL Script (Testing Database)

Run the following script to create the testing database. It creates a simple table called MYTABLE with a single row. (How to create a database from an SQL script):

CREATE TABLE MYTABLE (
    ID   INTEGER,
    VAL  BLOB SUB_TYPE 0 SEGMENT SIZE 80
);

Reading values

Because it is not possible to insert binary BLOB value in the SQL script we need to insert it in the code before reading.

The following sample prints the values from the column "VAL" to console:

string database = "test.fdb";

CreateEmbeddedDb(database, "test.sql");

FbConnectionStringBuilder csb = new FbConnectionStringBuilder();
csb.ServerType = 1;
csb.Database = database;

using (FbConnection c = new FbConnection(csb.ToString()))
{
	c.Open();
			
	FbCommand cmdInsert = new FbCommand("INSERT INTO mytable(id, val) VALUES(@id, @val)", c);
	cmdInsert.Parameters.Add("@id", 1);
	cmdInsert.Parameters.Add("@val", new byte[] {1, 2, 3});
	cmdInsert.ExecuteNonQuery();

	FbCommand cmd = new FbCommand("SELECT val FROM mytable", c);
				
	using (FbDataReader r = cmd.ExecuteReader())
	{
		while (r.Read())
		{
			int size = 20;
			byte[] bytes = new byte[size];
			long count = r.GetBytes(0, 0, bytes, 0, size);
			for(int i = 0; i < count; i++)
				Console.WriteLine("Value: " + bytes[i]);
		}
	}
}