A string containing no characters. You can use a zero-length string to indicate that you know there's no value for a field. You enter a zero-length string by typing two double quotation marks with no space between them (" "). In a Microsoft Access database, you can enter zero-length strings in Text, Memo, or Hyperlink fields if you set the AllowZeroLength property for the field to Yes. In a Microsoft Access project, you can enter zero-length strings in varchar and nvarchar fields. You can't enter zero-length strings in other types of fields. Zero-length strings are not supported in SQL Server 6.5.