topic Re: What does this error message mean: Operator '=' is not defined for the type DBNull and string "Stream Centerline" ? Does anyone know how I can fix this. Thank you in Water Resources Questions

What does this error message mean: Operator '=' is not defined for the type DBNull and string "Stream Centerline" ? Does anyone know how I can fix this. Thank you

PhilippaRawbone — Tue, 22 Mar 2016 17:25:53 GMT

I am using ArcMap and HEC-RAS to model the flood extent in Morpeth.

When trying to use the RAS Geometry-> Stream Centreline Atributes function the error message Operator '=' is not defined for the type DBNull and string "RiverWansbeck1" appears. RiverWansbeck1 being the stream centerline.

Does anyone know what this means and how I can fix it so it will work?

Thanks.

Re: What does this error message mean: Operator '=' is not defined for the type DBNull and string "Stream Centerline" ? Does anyone know how I can fix this. Thank you

TedKowal — Wed, 23 Mar 2016 16:08:34 GMT

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.

Re: What does this error message mean: Operator '=' is not defined for the type DBNull and string "Stream Centerline" ? Does anyone know how I can fix this. Thank you

DanPatterson_Retired — Wed, 23 Mar 2016 16:14:47 GMT

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.