This article was previously published under Q236605
When you use the Microsoft SQL Server Data Transformation Services (DTS) Import Wizard to import data from a Microsoft Excel worksheet, if a text column contains data that could be interpreted as mixed data (for example, alphanumeric characters representing hexadecimal data), the initial few rows determine the actual data type used and subsequent rows may be transferred as NULLs. DTS does not provide a warning message to indicate that some rows might not transfer.
Note If you are using SQL Server 2005, use the SQL Server Import and Export Wizard to perform the data transform.
This behavior is by design for the Excel ISAM. The first 8 rows determine the data type of the column. For example, if most of the first 8 rows contain numeric characters, the datatype of the column is a number. All subsequent values that do not fit that datatype are returned as NULL.
One workaround is to save the Excel sheet as a text file and then you use the DTS Wizard to import the file into SQL Server.
Steps To reproduce the behavior
For example, create the following worksheet in Excel:
The first column "Decimal" is formatted as General and the second column "HEX" is formatted as Text.
If you load this table from Excel into SQL Server using the DTS Wizard, rows 10-15 (values A-F) are NULL when loaded into a SQL table (the HEX column is formatted as Text in the workbook, but DTS makes it a Float type since it detects the source column as DBTYPE_R8 ).
For more information, see the "SQL Server Data Transformation Services" topic in SQL Server Books Online.