需要使用参数c＃从数据库中减去值

问题描述

我的代码减去了数据库中的值，当我想将它与datagridview一起使用时，请将它设置为参数而我无法使其成为

i had that code that minus value from database and when i want to use it with datagridview mus make it in parameter and i cant make it

SqlConnection con = new SqlConnection("Data Source=(local);Initial Catalog=inventory;Integrated Security=True");

           con.Open();
          for (int i = 0; i < dataGridView1.Rows.Count; i++)
            {
        SqlCommand com = new SqlCommand(" update product set quantity = quantity + '" + Convert.ToInt32(dataGridView1.Rows[i].Cells[5].Value ?? DBNull.Value) + "' where itemname = '"  + dataGridView1.Rows[i].Cells[0].Value ?? DBNull.Value + "' ", con);
          com.ExecuteNonQuery();
          }

因为当我用这种形式写它时我得到错误字符串后面的未闭合引号'منتج3'。



'منتج3'附近的语法不正确。



i认为它给了这个错误，因为它想要它在参数

because when i write it in this form i get error Unclosed quotation mark after the character string 'منتج 3'.

Incorrect syntax near 'منتج 3'.

i think it give m this error because it want it in parameter

推荐答案

using (SqlConnection connection = new SqlConnection("Data Source=(local);Initial Catalog=inventory;Integrated Security=True"))
{
    connnection.Open();

    using (SqlTransaction transaction = connection.BeginTransaction())
    using (SqlCommand command = new SqlCommand("UPDATE product SET quantity = quantity + @quantity WHERE itemname = @itemname", connection, transaction))
    {
        var pQuantity = command.Parameters.Add("@quantity", SqlDbType.Int);
        var pItemName = command.Parameters.Add("@itemname", SqlDbType.NVarChar, 50);

        for (int i = 0; i < dataGridView1.Rows.Count; i++)
        {
            pQuantity.Value = Convert.ToInt32(dataGridView1.Rows[i].Cells[5].Value);
            pItemName.Value = dataGridView1.Rows[i].Cells[0].Value ?? DBNull.Value;
            command.ExecuteNonQuery();
        }

        transaction.Commit();
    }
}

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