问题
I want to populate a drop down list at runtime in C#. I have a Date/Time field (e.g., 01/05/2000) in an Access 2003 database. I want to have the month name (i.e. January, February, ...) in the drop down list at runtime.
SELECT DISTINCT MonthName(Month(DATE_OF_BOOKING)) AS MNTH
FROM TRAVEL_DETAILS WHERE YEAR(DATE_OF_BOOKING)='2008'
The above query works fine while I'm running it from Access directly,
but when I'm trying to run it from an OledbCommand object in C# it says
Undefined function 'MonthName' in expression.
回答1:
Text from social msdn thread:
Custom user-written VBA functions as well as many built-in VBA language functions are executed by Microsoft Access when embedded in a SQL query. Unfortunately the functions available to the Jet database engine are limited (when executed via ADO, ADO.NET, etc.). You can find a list of those available in the following MS KB article:
How to configure Jet 4.0 to prevent unsafe functions from running in Access 2003.
EDIT: Use Format() method.
SELECT DISTINCT format(DATE_OF_BOOKING,'MMMM')
AS MNTH FROM TRAVEL_DETAILS WHERE YEAR(DATE_OF_BOOKING)='2008'
回答2:
MonthName is one of the many Access functions that was not supported by the ODBC and OLEDB drivers for the original "Jet" database engine, i.e.
Driver={Microsoft Access Driver (*.mdb)} for ODBC, orProvider=Microsoft.Jet.OLEDB.4.0 for OLEDB
but it is supported by the drivers for the newer "ACE" database engine
Driver={Microsoft Access Driver (*.mdb, *.accdb)} for ODBC, orProvider=Microsoft.ACE.OLEDB.12.0 for OLEDB
Microsoft Access Database Engine 2016 Redistributable
Microsoft Access Database Engine 2010 Redistributable
来源：https://stackoverflow.com/questions/4720788/month-name-of-date-field-in-access-database-from-external-application-c