/// <summary>
/// Executes the given SQL character sequence directly,
/// returning a scalar value.
/// </summary>
/// <param name="sql">
/// The SQL character sequence to execute.
/// </param>
/// <returns>
/// A scalar value representing the result of the execution.
/// </returns>
internal object ExecuteScalarDirect(string sql)
{
Request request = s_protocol.CreateExecuteDirectRequest(sql);
s_protocol.SetMaxRows(request, 1);
Response response = Execute(request);
if (response.isUpdateCount() ||
0 >= response.getColumnCount() ||
response.isEmpty())
{
return(null);
}
object value = response.rRoot.data[0];
if (value == null)
{
return(null);
}
else if (value is string)
{
return(value);
}
else
{
int type = response.metaData.colTypes[0];
return(HsqlConvert.FromJava.ToObject(value, type));
}
}
/// <summary>
/// Executes the given prepared request, returning a scalar value.
/// </summary>
/// <param name="request">The prepared request.</param>
/// <returns>
/// The scalar value. This is the first column of first row;
/// <c>null</c> when the result has no columns or no rows.
/// </returns>
internal object ExecuteScalarPrepared(Request request)
{
s_protocol.SetMaxRows(request, 1);
Response response = Execute(request);
if (response.isUpdateCount() ||
(0 >= response.getColumnCount()) ||
response.isEmpty())
{
return(null);
}
// No check for null pointers or array bounds violation.
// We cannot get this far and still
// have a rRoot == null, rRoot.data == null or
// rRoot.data.Length < 1 condition, unless
// there is an actual (and serious) bug in the
// underlying libraries.
object value = response.rRoot.data[0];
if (value == null)
{
return(null);
}
else if (value is string)
{
return(value);
}
else
{
int type = response.metaData.colTypes[0];
return(HsqlConvert.FromJava.ToObject(value, type));
}
}
