Seeing the code of the image I would recommend that you use parameters, concatenate in a string the values is not a good practice.
Your code should have the structure
using (SqlConnection conn = new SqlConnection("<connection string>"))
{
conn.Open();
string query = "INSERT INTO NombreTabla (campo1, campo2) VALUES (@param1, @param2)";
SqlCommand cmd = new SqlCommand(query, conn);
cmd.Parameters.AddWithValue("@param1", Convert.ToString(TextBox1.Text));
cmd.Parameters.AddWithValue("@param2", Convert.ToInt32(Textbox2.Text));
cmd.ExecuteNonQuery();
}
As you can see, do not concatenate the INSERT or UPDATE values, but assign them to the Parameters list, that's the way your code should look like
I leave an article where I explain how you could do this that I comment
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