问题描述
- executereader 要求已打开并可用的connection
-
private void button1_Click(object sender, EventArgs e)
{
SqlHelper.con.Open(); //这个是自己写的类
//里面就两句话
(
public static string connstring = "Data Source=.;Initial Catalog=students;Persist Security Info=True;User ID=sa;Password=Rootroot123";
public static SqlConnection con = new SqlConnection(connstring);
)string sql = "select * from student where sname = @sname"; SqlCommand cmd = new SqlCommand(sql, SqlHelper.con); cmd.Parameters.AddWithValue("@sname", comboBox1.Text); SqlDataReader reader = cmd.ExecuteReader(); while(reader.Read()) { sid.Text = reader[0].ToString(); name.Text = reader[1].ToString(); sex.Text = reader[2].ToString(); sclass.Text = reader[3].ToString(); score.Text = reader[4].ToString(); } }
只能点击按钮一次 不知道为什么
解决方案
private void button1_Click(object sender, EventArgs e)
{
SqlHelper.con.Open(); //这个是自己写的类
//里面就两句话
(
public static string connstring = "Data Source=.;Initial Catalog=students;Persist Security Info=True;User ID=sa;Password=Rootroot123";
public static SqlConnection con = new SqlConnection(connstring);
)
string sql = "select * from student where sname = @sname";
SqlCommand cmd = new SqlCommand(sql, SqlHelper.con);
cmd.Parameters.AddWithValue("@sname", comboBox1.Text);
SqlDataReader reader = cmd.ExecuteReader();
while(reader.Read())
{
sid.Text = reader[0].ToString();
name.Text = reader[1].ToString();
sex.Text = reader[2].ToString();
sclass.Text = reader[3].ToString();
score.Text = reader[4].ToString();
}
}
SqlHelper.con.Close(); //加上这个,关闭connection
时间: 2024-08-04 14:34:34