このエラーメッセージの意味は何ですか：Operator '=' is not defined for the type DBNull and string "Stream Centerline"？これを修正する方法を知っている方はいらっしゃいますか。ありがとうございます。

Question

<\/HEAD>私はArcMapとHEC-RASを使用してMorpethの洪水範囲をモデル化しています。<\/SPAN><\/P><\/P>RAS Geometry-> Stream Centreline Atributes機能を使用しようとしたときに、エラーメッセージOperator '=' is not defined for the type DBNull and string "RiverWansbeck1"が表示されます。RiverWansbeck1はstream centerlineです。<\/SPAN><\/P><\/P>これは何を意味し、どのように修正すれば動作するかご存知の方はいらっしゃいますか？<\/SPAN><\/P><\/P>ありがとうございます。<\/SPAN><\/P><\/BODY><\/HTML>

DanPatterson_Retired · Answer

Not sure what you are doing, but many times " = " an assignment statement (aka something is given the value of)

If it is a check for equality " == " is often used (aka is something equal to something else)

So your results need to be assessed in terms of assignment or equality checking for the language that is being used.

TedKowal · Answer

I am not a hydro or a hec user but the error code you are getting is a null value where it was not expected.  If you are reading from a dataset/database/FC One or more of the fields being used contains a null value.

If you are coding: You need and test to account for a null values.