c# - SQLDatasource parameters problem -

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why if use following instruction in code behind:

sqldatasource1.selectparameters["page"].defaultvalue = "0";

i 'system.nullreferenceexception: object reference not set instance of object.

'?

the 2 objects involves in single statement (bold)

sqldatasource1.selectparameters["page"].defaultvalue

sqldatasource1.selectparameters["page"].defaultvalue

so 1 of them must null. when looking @ previous question, because have not yet added "page" parameter sqldatasource1.


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