Operator ‘??’ cannot be applied to operands of type ‘string’ and ‘System.DBNull’
Both operands need to be object. Use explicit cast: (object)table.Value ?? DBNull.Value;
dbnull
Handle DBNull in C#
The shortest (IMHO) is: int stockvalue = (reader[“StockValue”] as int?) ?? 0; Explanation: If reader[“StockValue”] is of type int, the value will be returned, and the “??” operator will return the result If reader[“StockValue”] is NOT of type int (e.g. DBNull), null will be returned, and the “??” operator will return the value 0 (zero).
Why is this code invalid in C#?
The compiler requires that either the types of second and third operands are the same, or that one is implicitly convertible to the other. In your case, the types are DBNull and string, neither of which is implicitly convertible to the other. Casting either of them to object solves that. EDIT: Looks like it is … Read more
C# ADO.NET: nulls and DbNull — is there more efficient syntax?
Ah ha! I found an even more efficient solution than @Trebz’s! datePrm.Value = nullableDate ?? (object)DBNull.Value;
What is the point of DBNull?
I’m going to disagree with the trend here. I’ll go on record: I do not agree that DBNull serves any useful purpose; it adds unnecessary confusion, while contributing virtually no value. The argument is often put forward that null is an invalid reference, and that DBNull is a null object pattern; neither is true. For … Read more
DBNull if statement
This should work. if (rsData[“usr.ursrdaystime”] != System.DBNull.Value)) { strLevel = rsData[“usr.ursrdaystime”].ToString(); } also need to add using statement, like bellow: using (var objConn = new SqlConnection(strConnection)) { objConn.Open(); using (var objCmd = new SqlCommand(strSQL, objConn)) { using (var rsData = objCmd.ExecuteReader()) { while (rsData.Read()) { if (rsData[“usr.ursrdaystime”] != System.DBNull.Value) { strLevel = rsData[“usr.ursrdaystime”].ToString(); } } … Read more
handling dbnull data in vb.net
The only way that i know of is to test for it, you can do a combined if though to make it easy. If NOT IsDbNull(myItem(“sID”)) AndAlso myItem(“sID”) = sId Then ‘Do success ELSE ‘Failure End If I wrote in VB as that is what it looks like you need, even though you mixed languages. … Read more
What is the difference between null and System.DBNull.Value?
Well, null is not an instance of any type. Rather, it is an invalid reference. However, System.DbNull.Value, is a valid reference to an instance of System.DbNull (System.DbNull is a singleton and System.DbNull.Value gives you a reference to the single instance of that class) that represents nonexistent* values in the database. *We would normally say null, … Read more
SQLite equivalent to ISNULL(), NVL(), IFNULL() or COALESCE()
IFNULL, see here: http://www.sqlite.org/lang_corefunc.html#ifnull no brackets around the function
Most efficient way to check for DBNull and then assign to a variable?
I must be missing something. Isn’t checking for DBNull exactly what the DataRow.IsNull method does? I’ve been using the following two extension methods: public static T? GetValue<T>(this DataRow row, string columnName) where T : struct { if (row.IsNull(columnName)) return null; return row[columnName] as T?; } public static string GetText(this DataRow row, string columnName) { if … Read more