How can I check whether a table exists in SQL Server CE 3.5

问题

I have a database user.sdf in asp.net, I want to create the tables for that I need check it check it first exist are not if exist then need not create the tables, else create the new table how can I check it that please help me to resolve this.

回答1:

You can query the schema views in SQL CE 3.5 take a look here.

Here is a simple extension method that you could use.

public static class SqlCeExtentions
{
  public static bool TableExists(this SqlCeConnection connection, string tableName)
  {
    if (tableName == null) throw new ArgumentNullException("tableName");
    if (string.IsNullOrWhiteSpace(tableName)) throw new ArgumentException("Invalid table name");
    if (connection == null) throw new ArgumentNullException("connection");
    if (connection.State != ConnectionState.Open)
    {
      throw new InvalidOperationException("TableExists requires an open and available Connection. The connection's current state is " + connection.State);
    }

    using (SqlCeCommand command = connection.CreateCommand())
    {
      command.CommandType = CommandType.Text;
      command.CommandText = "SELECT 1 FROM Information_Schema.Tables WHERE TABLE_NAME = @tableName";
      command.Parameters.AddWithValue("tableName", tableName);
      object result = command.ExecuteScalar();
      return result != null;
    }
  }
}

You can use the above as follows

using (SqlCeConnection connection = new SqlCeConnection(@"Data Source=MyDatabase1.sdf"))
{
  connection.Open();
  if (connection.TableExists("MyTable"))
  {
     // The table exists
  }
  else
  {
    // The table does not exist
  }
}

回答2:

As an alternative you can Query the Table and catch the Exception thrown. If there is an Exception, the Table wasn't found, else the Table exists.

SELECT TOP 1 1 FROM TableName;

A little and simple Performance Test had better Results than the Query against INFORMATION_SCHEMA. Although I would consider a Query against INFORMATION_SCHEMA as cleaner.

来源：https://stackoverflow.com/questions/6316336/how-can-i-check-whether-a-table-exists-in-sql-server-ce-3-5

标签

ASP.NET

sql-server-ce