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);
}
public IDbCommand CreateRetrieveCommand <TSelect, TFrom, TWhere>(SelectExpression <TSelect>?selectCondition, FromExpression <TFrom>?fromCondition, WhereExpression <TWhere>?whereCondition)
where TSelect : Entity, new()
where TFrom : Entity, new()
where TWhere : Entity, new()
{
if (selectCondition == null)
{
return(AssembleCommand(true, GetSelectClauseStatement <TSelect, TFrom, TWhere>(), fromCondition, whereCondition, null));
}
else
{
return(AssembleCommand(true, selectCondition.ToString(), fromCondition, whereCondition, null));
}
}
public IDbCommand CreateCountCommand <T>(FromExpression <T>?fromCondition = null, WhereExpression <T>?whereCondition = null)
where T : Entity, new()
{
return(AssembleCommand(true, "SELECT COUNT(1) ", fromCondition, whereCondition, null));
}
public IDbCommand CreateRetrieveCommand <T1, T2, T3>(FromExpression <T1> fromCondition, WhereExpression <T1> whereCondition)
where T1 : Entity, new()
where T2 : Entity, new()
where T3 : Entity, new()
{
return(AssembleCommand(true, GetSelectClauseStatement <T1, T2, T3>(), fromCondition, whereCondition, null));
}
public IDbCommand CreateRetrieveCommand <T>(SelectExpression <T> selectCondition = null, FromExpression <T> fromCondition = null, WhereExpression <T> whereCondition = null)
where T : DatabaseEntity, new()
{
if (selectCondition == null)
{
return(AssembleCommand(true, GetSelectClauseStatement <T>(), fromCondition, whereCondition, null));
}
else
{
return(AssembleCommand(true, selectCondition.ToString(), fromCondition, whereCondition, null));
}
}
