怎么读取DataTable某一列的值？然后用c#代码判断是否有重复数据？linq还是怎么做呢？ 假设你上图表格数据为 datatable dt，列分别为aa，bb，cc，ddvar query=from p in dt.asenumerable()/分组 group p by new { t1=p.field(\"aa\").tostring().substring(0，p。.
怎么读取DataTable某一列的值？然后用c#代码判断是否有重复数据？linq还是怎么做呢？ public static void cs(){System.Data.DataTable dt=new System.Data.DataTable()；dt.Rows.Add(\"\")；var quer=from tb in dt.AsEnumerable()group tb by tb.Field(\"xx\")into xselect new{a=x.Key，b=x}；foreach(var c in quer){int i=0；foreach(var d in c.b){i+；}if(i>；1){有重复}}for(int i=0；i；i+){var qu=from tb in dt.AsEnumerable()where tb.Field(\"xx\")=dt.Rows[i][\"xx\"].ToString()select tb；if(qu.Count()>；1){有重复}}}两种方法 看你喜欢哪种
LINQ怎么根据“某个字段”去除重复数据查询（急求答案） Distinct方法的第二重载可以Enumerable.Distinct(IEnumerable，IEqualityComparer)，例如数据类为class School{public int Id { get；set；}public string Name { get；set；}是否重点学校public bool IsKeySchool { get；set；}}实现IEqualityComparer的比较器类为class SchoolComparer：EqualityComparer{public override bool Equals(School x，School y){return x.IsKeySchool=y.IsKeySchool；}public override int GetHashCode(School obj){return obj.IsKeySchool.GetHashCode()；}}原始列表为var schoolList=new List<；School>；{new School{Id=1，Name=\"三中\"，IsKeySchool=true}，new School{Id=2，Name=\"五中\"，IsKeySchool=true}，new School{Id=3，Name=\"十中\"，IsKeySchool=false}，new School{Id=4，Name=\"十五中\"，IsKeySchool=true}，new School{Id=5，Name=\"二十中\"，IsKeySchool=false}，}；执行var tempList=schoolList.Distinct(new SchoolComparer())；结果就只有两条“三中”和“十中”
linq 如何插入多条重复数据 protected void btnAdd_Click(object sender，EventArgs e){ using(var db=new myDataClassesDataContext()){ var q=（from o in db.UserTable select o.UserName.toarry()；if。q.contains(txtUserName.Text)){ UserTable u=new UserTable()；u.UserName=txtUserName.Text；u.UserPwd=txtUserPwd.Text；u.UserRight=DpLUserRight.Text；} } }
linq 怎么得到某数据集里相同的字段个数
