我在 Access 数据库上执行以下查询。该查询在 Access 中运行时会返回准确的结果。但是,当从代码运行时,我会取回数据库中的所有项目,即使是那些超出我正在搜索的日期范围的项目。
我想知道问题是否是因为参数名称与表中的列名称相同,所以我更改了参数名称@StartDate
和@EndDate
to@FromDate
并且@ToDate
这解决了问题,如果参数名称不同,我得到正确的结果集背部。这让我很担心,因为在我正在研究这种模式的项目中,到处都是重复的。但是,我使用一个名为的参数@Id
来更新记录Id
(db 表中的列名),这工作正常。这是一个奇怪的边缘案例吗?任何人都可以阐明这种行为。
为大量代码示例道歉,但在这种情况下,我认为需要整个方法。
public override AcademicCycleTransportCollection FetchForDateRange(DateTime startDate, DateTime endDate) {
const String query =
"PARAMETERS \n" +
" @StartDate DATE, \n" +
" @EndDate DATE \n" +
" ; \n" +
"SELECT \n" +
" [AcademicCycle].[Id] AS [Id], \n " +
" [AcademicCycle].[Name] AS [Name], \n " +
" [AcademicCycle].[AcademicCycleCategoryId] AS [AcademicCycleCategoryId], \n " +
" [AcademicCycle].[ParentAcademicCycleId] AS [ParentAcademicCycleId], \n " +
" [AcademicCycle].[StartDate] AS [StartDate], \n " +
" [AcademicCycle].[EndDate] AS [EndDate], \n " +
" [AcademicCycle].[IsPerpetual] AS [IsPerpetual], \n " +
" [AcademicCycle].[IsLocked] AS [IsLocked] \n " +
"FROM \n" +
" AcademicCycle \n" +
"WHERE \n" +
" (StartDate <= @EndDate AND EndDate >= @StartDate) OR \n" +
" IsPerpetual <> 0";
AcademicCycleTransportCollection transportCollection = new AcademicCycleTransportCollection();
OleDbCommand _fetchForDateRangeCommand = null;
if (_fetchForDateRangeCommand == null) {
OleDbConnection connection = _parentDataConnection.Connection;
_fetchForDateRangeCommand = new OleDbCommand(query, connection);
_fetchForDateRangeCommand.Parameters.Add("@StartDate", OleDbType.Date);
_fetchForDateRangeCommand.Parameters.Add("@EndDate", OleDbType.Date);
}
_fetchForDateRangeCommand.Transaction = _parentDataConnection.Transaction;
_fetchForDateRangeCommand.Parameters["@StartDate"].Value = startDate;
_fetchForDateRangeCommand.Parameters["@EndDate"].Value = endDate;
using (OleDbDataReader dbReader = _fetchForDateRangeCommand.ExecuteReader()) {
NullableDataReader reader = new NullableDataReader(dbReader);
while (reader.Read()) {
AcademicCycleTransport transport = FillTransport(reader);
transportCollection.Add(transport);
}
if (!reader.IsClosed) {
reader.Close();
}
}
return transportCollection;
}