Question

我在ms访问中创建了数据库，它有GPA列。在listbox2中，我需要列出哪些GPA大于2的学生。我是怎么做到的？

command.CommandText = "SELECT * FROM Student WHERE GPA > 2";
while (reader.Read())
{
  listBox2.Items.Add............?
}

如果可以，请提供帮助。

Answer 1

我不知道这只是你发布的伪代码。但是，如果没有，您正在阅读DataReader，该Command未初始化或未使用正确的CommandText - sql，因为您之前设置了command.CommandText = "SELECT * FROM Student WHERE GPA > 2"; using(var reader = command.ExecuteReader()) { while (reader.Read()) { // assuming that there's a column with name: StudentName listBox2.Items.Add(reader.GetString(reader.GetOrdinal("StudentName"))); } }一行。

{{1}}

Answer 2

string ConnectionString = "PUT YOU CONNECTION STRING HERE";

con = new SqlConnection(ConnectionString);
con.Open();
string CommandText = "SELECT * FROM Student WHERE GPA > 2";
cmd = new SqlCommand(CommandText);
cmd.Connection = con;
rdr = cmd.ExecuteReader();
lbx.Items.Clear();
while (rdr.Read())
{    
     lbx.Items.Add......
}

C＃访问数据库查询

2 个答案: