Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
385 views
in Technique[技术] by (71.8m points)

c# - Null value in a parameter varbinary datatype

How can I add a null value in a parameter varbinary datatype?

When I execute the following code:

using (SqlConnection myDatabaseConnection1 = new SqlConnection(myConnectionString.ConnectionString))
{
    using (SqlCommand mySqlCommand = new SqlCommand("INSERT INTO Employee(EmpName, Image) Values(@EmpName, @Image)", myDatabaseConnection1))
    {
        mySqlCommand.Parameters.AddWithValue("@EmpName", textBoxEmpName.Text);
        mySqlCommand.Parameters.AddWithValue("@Image", DBNull.Value);
        myDatabaseConnection1.Open();
        mySqlCommand.ExecuteNonQuery();
    }
}

I get the following System.Data.SqlClient.SqlException:

Implicit conversion from data type nvarchar to varbinary(max) is not allowed. Use the CONVERT function to run this query.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

I dont know the reason why "DBNull.Value" does not work for me. And I figure out another solution can solve this problem.

cmd.Parameters["@Image"].Value = System.Data.SqlTypes.SqlBinary.Null;

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...