How to save blob in bytes to sqlite

Hello! I'm a beginner with Unity. I'm having problem which I am trying to save a png to my database but the png needs to convert to bytes first.

 // Use this for initialization
 void Start () {
     if (Application.platform != RuntimePlatform.Android) {
         path = Application.dataPath + "/StreamingAssets/SqliteBlob.bytes";
     } else {
         path = Application.persistentDataPath + "/SqliteBlob.bytes";
         if (!File.Exists (path)) {
             WWW load = new WWW ("jar:file//" + Application.dataPath + "!/assets/" + "SqliteBlob.bytes");
             while (!load.isDone) {
             }
             File.WriteAllBytes (path, load.bytes);
         }
         
     
         //opening connection
         dbcon = new SqliteConnection ("URI = file:" + path);
         dbcon.Open ();


     //    GetImageTexture ("SELECT blobContent FROM 'blobTable' WHERE id='" + id + "' ", out BlobTexture, out BlobWidth, out BlobHeight);
     //    GameObject.Find ("ContentImage").GetComponent<Image> ().sprite = Sprite.Create (BlobTexture, new Rect (0, 0, BlobWidth, BlobHeight), new Vector2 (0.5f, 0.5f)); 

     }

 }

 // save image to blobtable db when the save_btn was click
 public void click_ImageSave(){
     Sprite blobR = Resources.Load("Images/white_black") as Sprite;
     Texture2D blobtex = blobR.texture;

     byte[] blobImage = blobtex.EncodeToPNG (); //returns bytes
     SaveBlobData("blobTable", blobImage);
     Debug.Log ("Successfully saved!");


 }


 public static bool SaveBlobData(String tableName, byte[] BlobContent) {

     string query;

     query = "INSERT INTO " + tableName + "(blobContent) VALUES (@BlobContent)";

     try {
         dbcmd = dbcon.CreateCommand();
         dbcmd.CommandText = query;
         SqliteParameter setParam = new SqliteParameter("@BlobContent", BlobContent);
         setParam.Size = BlobContent.Length;
         setParam.DbType = DbType.Binary;
         dbcmd.Parameters.Add(setParam);

         dbcmd.ExecuteNonQuery();

     } 

     catch(Exception ex) {
         Debug.LogError(ex.Message);
         return false;
     }

     return true;

 }


 void GetImageTexture(string Query, out Texture2D tex, out int width, out int height) {
     tex = new Texture2D (1024, 1024);
     tex.LoadImage (GetBlobData (Query));
     width = tex.width; 
     height = tex.height;    
 }

 public static byte[] GetBlobData(string Query){
     byte[] BlobContent = new byte[0];

     dbcmd = dbcon.CreateCommand();
     dbcmd.CommandText = Query;
     reader = dbcmd.ExecuteReader();

     while (reader.Read()) {
         BlobContent = (byte[])reader["blob"];
     }

     return BlobContent;
 }