Word 2002 introduced a new connection method: OLEDB. It supplants DDE as the default connection method. This has a number of consequences, some positive, others not.
On the positive side, the user can now connect to client/server databases such as SQL or Oracle without resorting to an intervening interface such as MSQuery, linked tables in Access or Excel, or creating the connection using VBA via ODBC.
OLEDB is, however, certainly slower than ODBC, and sometimes slower than DDE on an installation where DDE works well. Display of the Recipients dialog box can also affect the apparent speed when connecting to a data source.
Users of previous versions of Word who use Excel or Access data sources are often confused and frustrated when numeric and date formatting no longer come across the link into the mail merge. This is not a bug on the part of OLEDB - indeed, the same behaviour is also seen when using ODBC; it's a result of how data is stored.
Numeric data is stored for database access without formatting; the formatting is saved as part of the application interface. It's something you see when the data is displayed in its native application.
Both Excel and Access store dates and times as numbers: the integer part is the number of days since December 30, 1899, while the decimal part holds the time. Here, again, it is a format that Excel or Access stores for the cell or field that displays this information as understandable dates.
When DDE is used to make the connection, a conversation is carried out between Word and the Excel or Access environment, and thus, the formatting information is brought into the Mail merge as it appears in the application interface.
And ODBC or OLEDB connection, however, brings the data in directly - the application need not even be installed on the machine where Mail merge is running. And that's why you only get Word's very basic, default numeric or date formatting.
You have a number of options to present formatted numeric and date data in your Mail merge document, as described in the general Mail merge section.
On Windows installations where the short date format in the Regional settings is not the North American standard month/day/year, Excel and Access users will find that, in cases where the day is 12 or less, the month and day will come across the link reversed.
This is a bug; and comes from the OLEDB driver Microsoft provides for these two applications. Not only Word Mail merge users struggle with this problem - it also affects database programmers.
In this case, simply adding a formatting switch to the merge fields will not resolve the problem.
You have two choices: The data will have to be pre-formatted, as text, as described in the general Mail merge section; or use a DDE or ODBC connection.
You can get Word to use the default connection method from previous versions of Word by setting up the mail merge using the old Mail Merge Helper dialog box.
Or, you can manually select the connection method. In order to choose the preferred connection method: