SqlDataSource FilterExpression doesn't support LIKE + 'String__' pattern

[wubin_98]

When I set a SqlDataSource1.FilterExpression value to " Partnumber LIKE
'87-2055-___'" , SqlDataSource return empty. But I can get correct
result in SQL query by including above expression.

I also found that FilterExpression only support % (Any string of zero
or more characters) in the end of string. For example, "Partnumber LIKE
'87-2055-%' (OK). But "Partnumber LIKE '87-20%-012'" (Error).

Could anyone give an explanation?

Thanks,

BWU