To expand on Marc’s answer, I need to create a text file called Schema.ini and put it in the same directory as the CSV file. As well as column types, this file can specify the file format, date time format, regional settings, and the column names if they’re not included in the file.
To make the example I gave in the question work, the Schema file should look like this:
[Data.csv] ColNameHeader=True Col1=House Text Col2=Street Text Col3=Town Text
I could also try this to make the data provider examine all the rows in the file before it tries to guess the data types:
[Data.csv] ColNameHeader=true MaxScanRows=0
In real life, my application imports data from files with dynamic names, so I have to create a Schema.ini file on the fly and write it to the same directory as the CSV file before I open my connection.
Further details can be found here – http://msdn.microsoft.com/en-us/library/ms709353(VS.85).aspx – or by searching the MSDN Library for “Schema.ini file”.