如何将可为空的INT类型传递给INSERT INTO参数

Question

I need to pass in a nullable int type (passed in as an OPTIONAL param, sometimes it's defined, sometimes it's not...) into an INSERT INTO command in C# via paramters. Below is a screenshot of my code.

Here is the offending line of code, truncated for clarity...

public void WriteCustomColumns(... int? parentPlacementId = null)
{
    command.Parameters["@ParentPlacementId"].Value = (parentPlacementId == null ? System.Data.SqlTypes.SqlInt32.Null.Value : parentPlacementId);

Here is the screenshot of the error...

Answer 1

Try to not use the conditional operator

SqlParameter p = command.Parameters.Add("@ParentPlacementId", SqlDbType.BigInt);
if(parentPlacementId.HasValue) 
     p.Value = parentPlacementId; 
else 
     p.Value = DBNull.Value;

As a possible alternative (not recommended)

command.Parameters["@ParentPlacementId"].Value = 
     (parentPlacementId.HasValue ? (object)parentPlacementId.Value : (object)DBNull.Value);

Answer 2

Your code is failing because System.Data.SqlTypes.SqlInt32.Null throws SqlNullValueException when you try to access .Value .

Use just System.Data.SqlTypes.SqlInt32.Null .

Handling Null Values in ADO.NET

Answer 3

Use:

 command.Parameters["@ParentPlacementId"].Value = parentPlacementId.HasValue ? parentPlacementId.Value : System.Data.SqlTypes.SqlInt32.Null.Value;

Reference Microsoft's Using Nullable Type