SQL C# nvarchar类型转换为int类型 多表查询的问题，查询结果到新表，TXT数据读取到控件和数据库，生成在控件中的数据如何存到TXT文件中

CREATE VIEW temp AS
select StudentId, MAX(StudentScore) as M_Score
from T_StudentScores group by StudentId;

select * from T_StudentScores inner join temp
on temp.StudentId=T_StudentScores.StudentId and T_StudentScores.StudentScore=temp.M_Score

SELECT TOP * into newtable FROM [oldtable] Where UserID= Order By CreateTime Desc;
select * into newTable from temp

private void btnImport_Click(object sender, RoutedEventArgs e)
{
string connStr = ConfigurationManager.ConnectionStrings["dbStudentScoreStr"].ConnectionString;
OpenFileDialog ofd = new OpenFileDialog();
ofd.Filter = "文本文件|*.txt";
if (ofd.ShowDialog() == false)
{
return;
}
string[] lines = File.ReadLines(ofd.FileName, Encoding.Default).ToArray(); DataTable table = new DataTable();
table.Columns.Add("Id");
table.Columns.Add("StudentId");
table.Columns.Add("StudentName");
table.Columns.Add("Category");
table.Columns.Add("StudentScore");
//查看文件的编码格式，可以在文件->另存为->编码中查看，若是ANSI使用参数DEFAULT编码即可，
//若是UTF-8不使用参数，或是指定UTF-8即可
//使用如下的方式将其变成string数组 for (int i = ; i < lines.Count(); i++)
{
string line = lines[i];
//注意文件里是按制表符来分割的，不是字符串
string[] strs = line.Split('\t');//‘\t’为制表符
int id = Convert.ToInt32(strs[]);
string studentId = strs[];
string studentName = strs[];
string category = strs[];
string studentScore = strs[]; DataRow row = table.NewRow();//创建一个DataRow对象
row["Id"] = id;//一定要在一开始创建table.Columns添加列
row["StudentId"] = studentId;
row["StudentName"] = studentName;
row["Category"] = category;
row["StudentScore"] = studentScore;
table.Rows.Add(row);//NewRow只是创建，没有插入
}
using (SqlBulkCopy bulkCope = new SqlBulkCopy(connStr))
{
bulkCope.DestinationTableName = "T_StudentScores";
//添加dataTable中列名与数据库表中列名的映射
bulkCope.ColumnMappings.Add("Id", "Id");
bulkCope.ColumnMappings.Add("StudentId", "StudentId");
bulkCope.ColumnMappings.Add("StudentName", "StudentName");//dataTable中与数据库表的对应关系（datatable中的名字，数据库中的名字）
bulkCope.ColumnMappings.Add("Category", "Category");
bulkCope.ColumnMappings.Add("StudentScore", "StudentScore");
bulkCope.WriteToServer(table);
} MessageBox.Show("导入成功");
}

string[] lines = File.ReadAllLines("C:/Documents and Settings/Administrator/桌面/12.txt"); //读取所有行的代码
foreach (var line in lines)
{
string[] str = line.Split('\t');//分析数据是以Tab键分割的，所以去除
控件.Text = str[];
控件2.Text = str[];
}

private void btnOutput_Click(object sender, RoutedEventArgs e)
{
string str;
StudentDAL dal = new StudentDAL();
Student[] students = dal.ListStudentMaxScore();
StreamWriter sw = new StreamWriter(@"C:/Documents and Settings/Administrator/桌面/3.txt", false, Encoding.Default); for(int i=;i<students.Length;i++)
{
Student student = new Student();
student =students[i];
string stName=student.StudentName;
string tab="\t";
string stScort=student.StudentScore;
str = strcat(strcat(stName, tab), stScort); sw.WriteLine(str); }
sw.Close();
MessageBox.Show("成功导出！"); }

public void Save_Quit()
{
string[] str = { txtMinX.Text, txtMaxX.Text, txtMaxY.Text, txtMinY.Text };
StreamWriter sw = new StreamWriter(@"C:/Documents and Settings/Administrator/桌面/2.txt", false, Encoding.Default);
string str1;
for (int i = ; i < str.Length; i++)
{
str1 = str[i];
sw.WriteLine(str1); }
sw.Close();
this.Close(); }