Retrieve serial ID with Npgsql when inserting with ExecuteScalar

Question

I\'m trying to insert a row into a PostgreSQL table with a serial primary key and I need to retrieve this column after it was inserted. I got something like this:

Th

Answer 1

The insert itself does not cause a value to be returned. When you perform ExecuteScalar it is looking for a single value to be "Selected" so to speak.

I believe you need to follow up your insert with a select statement to solve your issue.
If you were using t-sql you would do this like so

string sql = "INSERT INTO [Table] (FieldName) VALUES (@ParamName); " + "SELECT CAST(scope_identity() AS int)";

ExecuteScalar would then return the unique id;

I am not sure of the exact syntax for postGresql but hopefully this allows you to solve your issue.