C# SqlCeCommand可空值
我的代码:C# SqlCeCommand可空值,c#,visual-studio-2010,sql-server-ce,C#,Visual Studio 2010,Sql Server Ce,我的代码: SqlCeConnection sql = new SqlCeConnection(@"Data Source=C:\DB.sdf"); sql.Open(); cmd = new SqlCeCommand("INSERT INTO xxx(aaa) VALUES(@aaa)", sql); String param = null; //doesn't work //String param = "blah" //works cmd.Parameters.AddWithValue(
SqlCeConnection sql = new SqlCeConnection(@"Data Source=C:\DB.sdf");
sql.Open();
cmd = new SqlCeCommand("INSERT INTO xxx(aaa) VALUES(@aaa)", sql);
String param = null; //doesn't work
//String param = "blah" //works
cmd.Parameters.AddWithValue("@aaa", param);
cmd.ExecuteNonQuery(); //(1)
sql.Close();
(1) 当param
为null时引发异常。数据库允许COLLMNaaa
中的值为空。如何在表xxx中插入null
例外情况:参数化查询“插入xxx(aaa)值(@aaa)”需要一个未提供的参数值。
使用
var param = DBNull.Value;
null与DBNull不是一回事请尝试改用
DBNull.Value
:
var param = DBNull.Value;
DBNull.Value能否转换为字符串?