[C#] Null value in SqlParameter

If you assign a null value to a SqlParameter object, it will cause an Error.
So the correct way is using DBNull.Value

For example,

sqlObj.SqlParams = new SqlParameter[]{

                    new SqlParameter("@TRANS_AMT", transLog.TransAmt),

                    new SqlParameter("@LEFT_BAL", transLog.LeftBal),

                    new SqlParameter("@LOG_TIME", transLog.LogTime)

                };

foreach(SqlParameter pa in sqlObj.SqlParams)

{

if(pa.Value==null)
{
   pa.Value = DBNull.Value;
}

}

When executing the sql query, the column in Database will be a NULL value when it’s assigned as DBNull.Value.

Reference
How to assign null to a sqlparameter?