UC知道C#数据库编程问题,会的速度进!
来源：百度知道 编辑：UC知道 时间：2024/07/13 00:56:52
textbox 的TextChanged事件,运行的时候出异常,说数据类型不匹配
private void txt_BookID_TextChanged(object sender, EventArgs e)
{
try
{
conn.Open();
string sql = "SELECT * FROM BOOKINFO WHERE BookID = '" + Convert.ToInt32(txt_BookID.Text) + " '";
OleDbCommand cmd = new OleDbCommand(sql, conn);
OleDbDataReader dr = cmd.ExecuteReader();//这行提示出异常
//如果读取成功，读取DataReader中的第一行
if (dr.Read())
{
//将各列的值对应显示在label控件中
lblISBN.Text = dr["ISBN"].ToString();
lblBookName.Text = dr["Name"].ToString();
lblAuthor.Text = dr["Author"].ToString();
lblPublisher.Text = dr["Publisher"].ToString();
lblPrice.Text = dr[&quo
private void txt_BookID_TextChanged(object sender, EventArgs e)
{
try
{
conn.Open();
string sql = "SELECT * FROM BOOKINFO WHERE BookID = '" + Convert.ToInt32(txt_BookID.Text) + " '";
OleDbCommand cmd = new OleDbCommand(sql, conn);
OleDbDataReader dr = cmd.ExecuteReader();//这行提示出异常
//如果读取成功，读取DataReader中的第一行
if (dr.Read())
{
//将各列的值对应显示在label控件中
lblISBN.Text = dr["ISBN"].ToString();
lblBookName.Text = dr["Name"].ToString();
lblAuthor.Text = dr["Author"].ToString();
lblPublisher.Text = dr["Publisher"].ToString();
lblPrice.Text = dr[&quo
首先你的数据库表 BookInfo的BookID字段是什么类型，如果为数值类型或自动编号的，就不能加单引号了，如果为字符型，应该加单引号。
如果为数值型，那么你的那个Sql语句应该改成这样：你可以试试
string sql = "SELECT * FROM BOOKINFO WHERE BookID = " + Convert.ToInt32(txt_BookID.Text) + "";
+ Convert.ToInt32(txt_BookID.Text) +
这句错了
你已经转成整型了怎么还能用字符串连接呢
直接用：
string sql = "SELECT * FROM BOOKINFO WHERE BookID = " + txt_BookID.Text.ToString();
如果bookid不是整型的就用：
string sql = "SELECT * FROM BOOKINFO WHERE BookID = '" + txt_BookID.Text.ToString() + "'";