public bool SchemaExists(DbConnection cn, string catalogName, string schemaName)
{
if (cn == null) throw new ArgumentNullException("cn");
if (catalogName == null) throw new ArgumentNullException("catalogName");
if (catalogName.Length == 0) throw new ArgumentException("catalogName");
if (schemaName == null) throw new ArgumentNullException("schemaName");
if (schemaName.Length == 0) throw new ArgumentException("schemaName");
return (cn.ImmediateExecuteSingleOrDefault<string>(
FormatSchemaExistsQuery(catalogName, schemaName)
, (DbDataReader reader) => { return reader.GetValueOrDefault(0, (string)null); }) != null);
}