"SqlParameterCollection only accepts non-null SqlParameter type objects, not String objects"
Solution 1
When you use Add
method, you are trying to add a new parameter. What you want to do is to assign value. So change this:
comm.Parameters.Add(dataGridView1.Rows[i].Cells[0].Value.ToString());
to this:
comm.Parameters["@author"].Value = dataGridView1.Rows[i].Cells[0].Value.ToString();
Similarly for the other parameters.
Solution 2
I tried all the above-mentioned steps but nothing helps.
Finally found and fixed it by changing the namespace
using System.Data.SqlClient to using Microsoft.Data.SqlClient
Arshad
Solution 3
I replaced my reference to System.Data.SqlClient with Microsoft.Data.SqlClient corrected the using statements and my problems went away
In my .csproj I now have
<ItemGroup>
<PackageReference Include="Microsoft.Data.SqlClient" Version="1.1.2" />
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.1.3" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.1.3" />
</ItemGroup>
But I also found I had use of the following scenario where I created a System.Data.SqlClient.SqlParameter
public static List<T> RunQuery<T>(ApiDbContext context, string query, Func<DbDataReader, T> map, params SqlParameter[] parameters)
{
var cn = context.Database.GetDbConnection();
var oldState = cn.State;
if (cn.State.Equals(ConnectionState.Closed)) { cn.Open(); }
using (var command = cn.CreateCommand())
{
command.CommandText = query;
command.CommandType = CommandType.Text;
foreach (var param in parameters)
{
var p = new System.Data.SqlClient.SqlParameter
{
ParameterName = param.ParameterName, Value = param.Value, SqlDbType = param.SqlDbType
};
command.Parameters.Add(p);
}
if (cn.State.Equals(ConnectionState.Closed)) { cn.Open(); }
var entities = new List<T>();
using (var result = command.ExecuteReader())
{
while (result.Read())
{
entities.Add(map(result));
}
}
if (oldState.Equals(ConnectionState.Closed) && cn.State == ConnectionState.Open) { cn.Close(); }
return entities;
}
}
Solution 4
I had been getting the same error and had to use AddWithValue
like this...
cmd.Parameters.AddWithValue(@columnToUpdate, newValue);
cmd.Parameters.AddWithValue(@conditionalColumn, conditionalValue);
Solution 5
Try below
comm.Parameters.Add("@author", SqlDbType.VarChar);
comm.Parameters["@author"].Value = dataGridView1.Rows[i].Cells[0].Value.ToString();
Ruchir Sharma
I'm an engineering graduate in Computer Science, who likes learning stuff about C# and PHP.
Updated on July 05, 2021Comments
-
Ruchir Sharma almost 3 years
I keep getting the exception
The SqlParameterCollection only accepts non-null SqlParameter type objects, not String objects
while executing the following code:
string StrQuery; using (SqlConnection conn = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=SanFransiscoData;Integrated Security=True;Pooling=False")) { using (SqlCommand comm = new SqlCommand()) { comm.Connection = conn; conn.Open(); // SqlParameter author = new SqlParameter("@author", dataGridView1.Rows[0].Cells[0].Value.ToString()); comm.Parameters.Add("@author", SqlDbType.VarChar); comm.Parameters.Add("@title", SqlDbType.NVarChar); comm.Parameters.Add("@genre", SqlDbType.VarChar); comm.Parameters.Add("@price", SqlDbType.Float); comm.Parameters.Add("@publish_date", SqlDbType.Date); comm.Parameters.Add("@description", SqlDbType.NVarChar); comm.Parameters.Add("@bookid", SqlDbType.VarChar); for (int i = 0; i < dataGridView1.Rows.Count; i++) { StrQuery = "INSERT INTO BooksData VALUES(@author,@title,@genre,@price,@publish_date,@description,@bookid)"; comm.Parameters.Add(dataGridView1.Rows[i].Cells[0].Value.ToString()); comm.Parameters.Add(dataGridView1.Rows[i].Cells[1].Value.ToString()); comm.Parameters.Add(dataGridView1.Rows[i].Cells[2].Value.ToString()); comm.Parameters.Add(Convert.ToDecimal(dataGridView1.Rows[i].Cells[3].Value)); comm.Parameters.Add(Convert.ToDateTime(dataGridView1.Rows[i].Cells[4].Value)); comm.Parameters.Add(dataGridView1.Rows[i].Cells[5].Value.ToString()); comm.Parameters.Add(dataGridView1.Rows[i].Cells[6].Value.ToString()); comm.CommandText = StrQuery; comm.ExecuteNonQuery(); } } }
Please tell me where I'm going wrong.