问题
I have an SQL 2008 server, in the server is a table that has a column with a data type of varchar(MAX). I am trying to import certain columns from this table into Excel 2010 using ADO. Here is an example of the code I am using:
Dim con As Object
Set con = CreateObject("ADODB.Connection")
cmd.CommandText = "SELECT dbo.(Table Name).Name From dbo.(Table)"
cmd.CommandType = 1
con.open
cmd.ActiveConnection = con
Dim rst as Object
set rst = cmd.Execute
ActiveSheet.cells(targetRange.Row, targetRange.Column).CopyFromRecordset rst
The code executes just fine, however because the column Name is set to varchar(MAX) none of the names show up in the worksheet. I know this because I made a copy of the SQL server and changed the data type for the column to varchar(1024) and it works the way it should.
I also tried placing the data in the recordset into the spreadsheet manually but with no luck. So the problem is I can not change the real SQL server.
Is there a command that I can add to the Select statement or a cast that I can use that will convert the varchar(MAX) to a data type that Excel can use, or is there something else I can do so that the data is not null when I read it in?
I have been looking into this problem for a day now with some threads coming close but they are talking about using select on the SQL server with a cast which doesn't work in this case, or in some other program, which doesn't help.
回答1:
ADO apparently doesn't handle VARCHAR(MAX) properly (or how you might expect), something about returning a zero column size as its not defined like it would be for VARCHAR(n).
You answered your own question, as you just needed to cast your column to something with a defined length!
CAST(column AS type)
or in your case
SELECT CAST(dbo.(Table Name).Name AS VARCHAR(1024)) FROM dbo.(Table)
来源：https://stackoverflow.com/questions/15418712/recordset-field-values-return-null-from-sql-server-with-varcharmax-data-type