c# - Window Form C# MS Access 检查是否已经具有该数据的值

Question

如何检查数据是否已存在于 MS Access 中？例如，如果名字是 blouse 是 Bijan，那么当我要发布时，消息框将显示在告诉我们 Bijan 已经在表中。

//Button Post
private void buttonPost_Click(object sender, EventArgs e)
{
    //Connect to database
    connection.Open();
    command.Connection = connection;
    //Password need to use [] because it is reserved keyword
    command.CommandText = "INSERT INTO BlouseTable (blouseName,blouseBrand,blouseColor,blouseSize,blouseQuantity) "
        + "VALUES ('" + blouse.BlouseName + "','" + blouse.BlouseBrand
        + "','" + blouse.BlouseColor + "','" + blouse.BlouseSize 
        + "','" + blouse.BlouseQuantity  + "')";

    command.ExecuteNonQuery();
    //Display the message result
    MessageBox.Show("Done post new Blouse!");
    //Close the connection after done post new blouse
    connection.Close();
}

这是我窗口表单中的按钮帖子。所以，当我按下它时，它应该是 MS Access 中的数据库表。

Answer 1

试试这个。

OleDbCommand commandBlouseName = new OleDbCommand();
commandBlouseName.Connection = connection;
commandBlouseName.CommandText = "SELECT * FROM BlouseTable WHERE blouseName='" + blouse.BlouseName + "'";
OleDbDataReader readerBlouseName = commandBlouseName.ExecuteReader();
int count = 0;
while (readerBlouseName.Read())
{
    count++;
}
if (count == 1)
{
    //Has 1 same name registered
}
if (count < 1)
{
    //Create new one
    //There is no Blouse Name registered with same name
}
if (count > 1)
{
    //More than 1 that Blouse Name registered
}