英文:
Update statement does nothing
问题
当我在ChbBeds_numericUpDown中输入一个数字并点击“更新”按钮时，它会显示“数据已更新”，但数据库中没有任何变化。
private void ChbUp_button_Click(object sender, EventArgs e)
{
try
{
string statement = "UPDATE ChamberXPavilions SET Beds count = @beds_count WHERE Pav_name = @pav_name AND Chamber_number = @chamber_number";
cmd = new OleDbCommand(statement, conn);
cmd.Parameters.AddWithValue("@pav_name", Chbpav_comboBox.Text);
cmd.Parameters.AddWithValue("@chamber_number", Chb_numericUpDown.Value);
cmd.Parameters.AddWithValue("@beds_count", ChbBeds_numericUpDown.Value);
conn.Open();
cmd.ExecuteNonQuery();
conn.Close();
MessageBox.Show("数据已更新");
showdata();
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
SQL语句有问题吗？
英文:
When I enter a number in the ChbBeds_numericUpDown and click on the "Update" button, it says "Data Updated", but nothing changes in the database
private void ChbUp_button_Click(object sender, EventArgs e)
{
try
{
string statement = "UPDATE ChamberXPavilions SET Beds count = @beds_count WHERE Pav_name = @pav_name AND Chamber_number = @chamber_number";
cmd = new OleDbCommand(statement, conn);
cmd.Parameters.AddWithValue("@pav_name", Chbpav_comboBox.Text);
cmd.Parameters.AddWithValue("@chamber_number", Chb_numericUpDown.Value);
cmd.Parameters.AddWithValue("@beds_count", ChbBeds_numericUpDown.Value);
conn.Open();
cmd.ExecuteNonQuery();
conn.Close();
MessageBox.Show("Data updated");
showdata();
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
Is the SQL statement wrong ?
答案1
得分: 1
与 SQL Server 相反，MS Access 的 OleDB 提供程序不支持命名参数，而是使用位置参数。
在你的情况下，你有一个 SQL 语句：
UPDATE ChamberXPavilions
SET Beds count = @beds_count
WHERE Pav_name = @pav_name AND Chamber_number = @chamber_number
所以你需要按照相同的顺序提供参数 - 首先是 @beds_count，然后是 @pav_name，最后是 @chamber_number。
因此，尝试使用以下代码提供参数值：
cmd = new OleDbCommand(statement, conn);
cmd.Parameters.AddWithValue("@beds_count", ChbBeds_numericUpDown.Value);
cmd.Parameters.AddWithValue("@pav_name", Chbpav_comboBox.Text);
cmd.Parameters.AddWithValue("@chamber_number", Chb_numericUpDown.Value);
现在，你的 UPDATE 语句应该能够获取正确的值，并且应该可以正常工作。
英文:
Contrary to SQL Server, the OleDB provider for MS Access does NOT work with named parameters - instead, it uses positional parameters.
In your case, you have a SQL statement
UPDATE ChamberXPavilions
SET Beds count = @beds_count
WHERE Pav_name = @pav_name AND Chamber_number = @chamber_number
so you need to also provide the parameters in the same order - first @beds_count, then @pav_name and finally @chamber_number.
So try this for providing the parameter values:
cmd = new OleDbCommand(statement, conn);
cmd.Parameters.AddWithValue("@beds_count", ChbBeds_numericUpDown.Value);
cmd.Parameters.AddWithValue("@pav_name", Chbpav_comboBox.Text);
cmd.Parameters.AddWithValue("@chamber_number", Chb_numericUpDown.Value);
Now, your UPDATE statement should get the proper values and should now work
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