问题
You can use the Filter property of a BindingSource to do SQL like filtering. For example:
bindingSource.Filter= "Activated = 1"
Is there something like documentation on the exact syntax of this?
I would like to check if a field is not DBNull, so i tried "Field != NULL" but it gives a syntax error.
回答1:
The syntax is generally the same as what would you would use in a SQL Where clause, without the "Where", so in this case, it would be
bindingSource.Filter = "Field <> NULL";
If you look at msdn docs for BindingSource.Filter you will see this:
"To form a filter value, specify the name of a column followed by an operator and a value to filter on. The accepted filter syntax depends on the underlying data source. If the underlying data source is a DataSet, DataTable, or DataView, you can specify Boolean expressions using the syntax documented for the DataColumn..::.Expression property."
Follow that link to see all the detailed rules
回答2:
Have a look at this msdn article. The described syntax should be valid for your BindingSource, too.
回答3:
What worked for me was
bindingSource.Filter = "columnName Is Null";
or conversely
bindingSource.Filter = "columnName Is Not Null";
来源：https://stackoverflow.com/questions/1389831/net-bindingsource-filter-syntax-reference