/// <summary>
///
/// </summary>
/// <typeparam name="TSource"></typeparam>
/// <typeparam name="T"></typeparam>
/// <param name="model"></param>
/// <param name="exp"></param>
/// <param name="optor"></param>
/// <param name="dao"></param>
/// <param name="conn"></param>
/// <param name="trns"></param>
/// <returns></returns>
private static T QueryAggregate <TSource, T>(
TSource model,
Expression <Func <TSource, T> > exp,
string optor,
IDBUtil dao,
DbConnection conn = null, DbTransaction trns = null) where TSource : IDBEntity
{
//要查詢的欄位
string propName = ((MemberExpression)exp.Body).Member.Name;
//處理 where 參數
var whereParams = prepareWhereParams(model.GetOperating().WHERE_LIST);
var selectColumns = new List <string>();
selectColumns.Add(optor + "(" + propName + ") AS result");
//查詢
var resultList = dao.QueryByTable(model.GetTableName(), selectColumns, whereParams, conn, trns);
if (resultList != null && resultList.Count > 0 && !DBNull.Value.Equals(resultList[0]["result"]))
{
Func <object, object> converter = ClassUtil.GetConvertFuncMap()[typeof(T)];
return((T)converter(resultList[0].SafeGetValue("result")));
}
return(default(T));
}