SqlCeEngineEx – Extending the SqlCeEngine class

I use System.Data.SqlServer.SqlCeEngine() quite a lot in all my projects. I normally create the database on the fly when the application is launched for the first time and then I populate the initial data via a web service.

I often check if database objects exist before I create them. You can do this by querying the INFORMATION_SCHEMA views. I created a helper class called SqlCeEngineEx that contains the following methods for querying the INFORMATION_SCHEMA:

1) bool DoesTableExist(string table) – Checks if a table exists in the database
2) string[] GetTables() – Returns a string array of all the tables in the database
3) string[] GetTableConstraints(string table) – Returns a string array of all the constraints for a table
4) string[] GetTableConstraints() – Returns a string array of all the constraints in the database

And here is the full code:

public class SqlCeEngineEx : IDisposable
{
  private SqlCeEngine engine;

  public SqlCeEngineEx()
  {
   engine = new SqlCeEngine();
  }

  public SqlCeEngineEx(string connectionString)
  {
   engine = new SqlCeEngine(connectionString);
  }

  public bool DoesTableExist(string tablename)
  {
   bool result = false;

   using (SqlCeConnection conn = new SqlCeConnection(LocalConnectionString)) {
    conn.Open();
    using (SqlCeCommand cmd = conn.CreateCommand()) {
     cmd.CommandText =
      @”SELECT COUNT(TABLE_NAME)
       FROM INFORMATION_SCHEMA.TABLES
       WHERE TABLE_NAME=@Name”;
     cmd.Parameters.AddWithValue(“@Name”, tablename);
     result = Convert.ToBoolean(cmd.ExecuteScalar());
    }
   }

   return result;
  }

  private string[] PopulateStringList(SqlCeCommand cmd)
  {
   List list = new List();

   using (SqlCeDataReader reader = cmd.ExecuteReader()) {
    while (reader.Read()) {
     list.Add(reader.GetString(0));
    }
   }

   return list.ToArray();
  }

  public string[] GetTables()
  {
   string[] tables;

   using (SqlCeConnection conn = new SqlCeConnection(LocalConnectionString)) {
    conn.Open();
    using (SqlCeCommand cmd = conn.CreateCommand()) {
     cmd.CommandText = “SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES”;
     tables = PopulateStringList(cmd);
    }
   }

   return tables;
  }

  public string[] GetTableConstraints()
  {
   string[] constraints;

   using (SqlCeConnection conn = new SqlCeConnection(LocalConnectionString)) {
    conn.Open();
    using (SqlCeCommand cmd = conn.CreateCommand()) {
     cmd.CommandText = “SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS”;
     constraints = PopulateStringList(cmd);
    }
   }

   return constraints;
  }

  public string[] GetTableConstraints(string tablename)
  {
   string[] constraints;

   using (SqlCeConnection conn = new SqlCeConnection(LocalConnectionString)) {
    conn.Open();
    using (SqlCeCommand cmd = conn.CreateCommand()) {
     cmd.CommandText =
      @”SELECT CONSTRAINT_NAME
       FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
       WHERE TABLE_NAME=@Name”;
     cmd.Parameters.AddWithValue(“@Name”, tablename);
     constraints = PopulateStringList(cmd);
    }
   }

   return constraints;
  }

  public string LocalConnectionString
  {
   get { return engine.LocalConnectionString; }
   set { engine.LocalConnectionString = value; }
  }

  public void Compact()
  {
   engine.Compact(null);
  }

  public void Compact(string connectionString)
  {
   engine.Compact(connectionString);
  }

  public void CreateDatabase()
  {
   engine.CreateDatabase();
  }

  public void Repair(string connectionString, RepairOption options)
  {
   engine.Repair(connectionString, options);
  }

  public void Shrink()
  {
   engine.Shrink();
  }

  public bool Verify()
  {
   return engine.Verify();
  }

  public void Dispose()
  {
   engine.Dispose();
   engine = null;
  }
}