private IDbCommand AssembleCommand <TFrom, TWhere>(bool isRetrieve, string selectClause, FromExpression <TFrom>?fromCondition, WhereExpression <TWhere>?whereCondition, IList <IDataParameter>?parameters)
where TFrom : Entity, new()
where TWhere : Entity, new()
{
IDbCommand command = _databaseEngine.CreateEmptyCommand();
command.CommandType = CommandType.Text;
command.CommandText = selectClause;
if (isRetrieve)
{
if (fromCondition == null)
{
fromCondition = NewFrom <TFrom>();
}
command.CommandText += fromCondition.ToString();
foreach (KeyValuePair <string, object> pair in fromCondition.GetParameters())
{
IDataParameter param = _databaseEngine.CreateParameter(pair.Key, pair.Value);
command.Parameters.Add(param);
}
}
if (whereCondition != null)
{
command.CommandText += whereCondition.ToString();
foreach (KeyValuePair <string, object> pair in whereCondition.GetParameters())
{
IDataParameter param = _databaseEngine.CreateParameter(pair.Key, pair.Value);
command.Parameters.Add(param);
}
}
if (parameters != null)
{
foreach (IDataParameter param in parameters)
{
command.Parameters.Add(param);
}
}
return(command);
}
