User-837620913 posted
You can't do this in ODBC. You can change the number of rows to scan, but that does not guarantee it will work. Also, there is a bug in the RowsToScan property in that ODBC basically ignores it.
From
here about half-way down the article:
Rows to Scan: Excel does not provide ADO with detailed schema information about the data it contains, as a relational database would. Therefore, the driver must scan through at least a few rows of the existing data
in order to make an educated guess at the data type of each column. The default for "Rows to Scan" is eight (8) rows. You can specify an integer value from one (1) to sixteen (16) rows, or you can specify zero (0) to scan all existing rows. This is done by
adding the optional MaxScanRows= setting to the connection string, or by changing the Rows to Scansetting in the DSN configuration dialog box.
However, due to a bug in the ODBC driver, specifying the Rows to Scan (MaxScanRows) setting currently has no effect. In other words, the Excel ODBC driver (MDAC 2.1 and later) always scans the first 8 rows in the specified data source in order to determine
each column's datatype.
For a workaround of this bug you have to modify the registry. If you want to do that, check this support article.
http://support.microsoft.com/kb/189897/EN-US
