problem with my database

hello
i have a problem in retrieving data from my database .
i use those scripts bellow to read the database and to select data from it

Code (CSharp):

1. public ArrayList ReadFullTable (string tableName)
2.     {
3.         string query;
4.         query = "SELECT * FROM " + tableName;
5.         dbcmd = dbcon.CreateCommand ();
6.         dbcmd.CommandText = query;
7.         reader = dbcmd.ExecuteReader ();
8.         ArrayList readArray = new ArrayList ();
9.         while (reader.Read())
10.         {
11.             ArrayList lineArray = new ArrayList ();
12.             for (int i = 0; i < reader.FieldCount; i++)
13.             {
14.                 lineArray.Add (reader.GetValue (i));
15.             } // This reads the entries in a row
16.             readArray.Add (lineArray); // This makes an array of all the rows
17.         }
18.         return readArray; // return matches
19.     }
20. public string QueryString(string tablename, string column, string col_name, string value)
21.     {
22.                 string text = "Not Found";
23.                 string query;
24.                 query = "SELECT " + column + " FROM " + tablename + " WHERE " + col_name + "='" + value + "'";  
25.                 dbcmd = dbcon.CreateCommand ();
26.                 dbcmd.CommandText = query;
27.                 reader = dbcmd.ExecuteReader ();
28.  
29.         if(reader.Read())
30.         text = reader.GetString(0);
31.         else
32.             Debug.Log("QueryString - nothing to read...");
33.         reader.Close();
34.         dbcon.Close();
35.         return text;
36.     }

and i have anther script

Code (CSharp):

1. private string firstName = "First Name";
2.     private string  lastName = "Last Name";
3.     private string get = "GET";
4.     private string find = "FIND";
5.     private int DatabaseEntryStringWidth = 100;
6.     private Vector2 scrollPosition ;
7.     private ArrayList databaseData = new ArrayList ();
8.    
9.     // This GUI provides us with a way to enter data into our database
10.     //  as well as a way to view it
11.     void OnGUI ()
12.     {
13.         GUI.Box (new Rect (25, 25, Screen.width - 50, Screen.height - 50), "");
14.         GUILayout.BeginArea (new Rect (50, 50, Screen.width - 100, Screen.height - 100));
15.         // This first block allows us to enter new entries into our table
16.         GUILayout.BeginHorizontal ();
17.         firstName = GUILayout.TextField (firstName, GUILayout.Width (DatabaseEntryStringWidth));
18.         lastName = GUILayout.TextField (lastName, GUILayout.Width (DatabaseEntryStringWidth));
19.         get = GUILayout.TextField (get, GUILayout.Width (DatabaseEntryStringWidth));
20.         find = GUILayout.TextField (find, GUILayout.Width (DatabaseEntryStringWidth));
21.         GUILayout.EndHorizontal ();
22.        
23.         if (GUILayout.Button ("Add to database"))
24.         {
25.             // Insert the data
26.             InsertRow (firstName, lastName);
27.             // And update the readout of the database
28.             databaseData = ReadFullTable ();
29.  
30.         }
31.         // This second block gives us a button that will display/refresh the contents of our database
32.         GUILayout.BeginHorizontal ();
33.         if (GUILayout.Button ("Read Database"))
34.         {
35.             databaseData = ReadFullTable ();
36.        
37.         }
38.         if (GUILayout.Button ("Clear"))
39.         {
40.             databaseData.Clear ();
41.         }
42.         GUILayout.EndHorizontal ();
43.        
44.         GUILayout.Label ("Database Contents");
45.         scrollPosition = GUILayout.BeginScrollView (scrollPosition, GUILayout.Height (100));
46.         foreach (ArrayList line in databaseData)
47.         {
48.             GUILayout.BeginHorizontal ();
49.             foreach (object s in line)
50.             {
51.                 GUILayout.Label (s.ToString (), GUILayout.Width (DatabaseEntryStringWidth));
52.             }
53.             GUILayout.EndHorizontal ();
54.         }
55.        
56.         GUILayout.EndScrollView ();
57.         if (GUILayout.Button("search"))
58.             {
59.             get = GetDefinitation(find);
60.             databaseData = ReadFullTable();
61.             }
62.         if (GUILayout.Button ("Delete All Data"))
63.         {
64.             DeleteTableContents ();
65.         databaseData = ReadFullTable ();
66.         }
67.        
68.         GUILayout.EndArea ();
69.     }
70.    
71.     // Wrapper function for inserting our specific entries into our specific database and table for this file
72.     private void InsertRow (string firstName, string lastName)
73.     {
74.         string[] values = new string[]{("'" + firstName + "'"), ("'" + lastName + "'")};
75.         db.InsertInto (TableName, values);
76.     }
77.    
78.     // Wrapper function, so we only mess with our table.
79.     private ArrayList ReadFullTable ()
80.     {
81.         return db.ReadFullTable(TableName);
82.     }
83.     public string GetDefinitation(string value)
84.     {
85.         return db.QueryString(TableName,"lastName","firstName", value);
86.     }
87.     // Another wrapper function...
88.     private void DeleteTableContents ()
89.     {
90.         db.DeleteTableContents (TableName);
91.     }
92. }

all the button works fine but the problem is in the button called 'search' when i click on it i have an error "SqliteSyntaxException: out of memory"
i can't find where the problem is ?!! can anyone help me please ?!
thank you