我用Google搜索了这个错误,并没有得出结论为什么我收到这个错误.我正在尝试用一些数据填充DataGridView.这是我的代码.
Private Sub LoadGrid()
Dim cmd As New OleDbCommand
Dim dt As DataTable
With cmd
.CommandText = "project_master_query"
.CommandType = CommandType.StoredProcedure
.Connection = New OleDbConnection(My.Settings.cnnString)
End With
dt = GetData(cmd)
dgvData.DataSource = dt
End Sub
Private Function GetData(ByVal cmd As OleDbCommand) As DataTable
Dim dt As New DataTable
Using cmd.Connection
cmd.Connection.Open()
dt.Load(cmd.ExecuteReader(CommandBehavior.CloseConnection))
End Using
Return dt
End Function
查询存储在Access中的“project_master_query”.
SELECT project_master.*,location_master.LocationName,project_currentmilestonedef.MilestoneDefID,project_currentmilestonedef.MilestoneName,project_regions.RegionName,owner_fullname.FullName AS OwnerFullName,designer_fullname.FullName AS DesignerFullName,project_issuecount.HasOpenIssues,project_updated_closedate.UpdatedCloseDate,project_bonusdays.BonusDays,project_bonusdays.IsGreen,project_bonusdays.IsYellow,project_bonusdays.IsRed,checklist_days_perproject_defined_1.Week1,checklist_days_perproject_defined_1.Week2,checklist_days_perproject_defined_1.Week3,checklist_days_perproject_defined_1.Week4,project_issueduration.ProjectIssueDurationDays,project_active_status.ProjectIsOpen,project_requirement_status.RequirementStatusName,priority_def.PriorityShortName
FROM project_requirement_status
RIGHT JOIN (project_regions
RIGHT JOIN (priority_def RIGHT JOIN (location_master
RIGHT JOIN ((((checklist_days_perproject_defined AS checklist_days_perproject_defined_1
RIGHT JOIN ((((((((contacts_fullname AS designer_fullname
RIGHT JOIN (contacts_fullname AS owner_fullname
RIGHT JOIN project_master ON owner_fullname.ContactID = project_master.ContactOwner)
ON designer_fullname.ContactID = project_master.ContactDesigner)
LEFT JOIN project_issuecount
ON project_master.ProjectID = project_issuecount.ProjectID)
LEFT JOIN project_currentmilestonedef
ON project_master.ProjectID = project_currentmilestonedef.ProjectID)
LEFT JOIN project_within_benchmark_week1
ON project_master.ProjectID = project_within_benchmark_week1.ProjectID)
LEFT JOIN project_within_benchmark_week2
ON project_master.ProjectID = project_within_benchmark_week2.ProjectID)
LEFT JOIN project_within_benchmark_week3
ON project_master.ProjectID = project_within_benchmark_week3.ProjectID)
LEFT JOIN project_updated_closedate
ON project_master.ProjectID = project_updated_closedate.ProjectID)
LEFT JOIN checklist_days_perproject_defined
ON project_master.ProjectID = checklist_days_perproject_defined.ProjectID)
ON checklist_days_perproject_defined_1.ProjectID = project_master.ProjectID)
LEFT JOIN project_issueduration
ON project_master.ProjectID = project_issueduration.ProjectID)
LEFT JOIN project_active_status
ON project_master.ProjectID = project_active_status.ProjectID)
LEFT JOIN project_bonusdays ON project_master.ProjectID = project_bonusdays.ProjectID)
ON location_master.LocationID = project_master.Location)
ON priority_def.PriorityDefID = project_master.ProjectPriority)
ON project_regions.RegionID = project_master.Region)
ON project_requirement_status.RequirementStatusID = project_master.RequirementStatus;
解决方法
Nz函数很可能出现在您在多个连接中引用的视图/查询中.你必须仔细研究它们.
由于Nz()是Access应用程序的一个功能而不是Access驱动程序,因此只要您尝试从Access应用程序外部使用它,它就会失败.您可以使用IIf(IsNull())构造替换Nz.
放在一起时：
Nz(expr,[valueifnull])
变
IIf(IsNull(expr),valueifnull,valueifnotnull)
例子
默认值：Nz(tbl.A)=> IIf(IsNull(tbl.A),”,tbl.A)
使用后备：Nz(tbl.A,tbl.B)=> IIf(IsNull(tbl.A),tbl.B,tbl.A)
