C # datatable Filters duplicate data for a column (equivalent to distinct)

1. Description of the problem

In the program code has a query out of the DataTable, call him a, the data structure is as follows:

A table

Date	Detection Method	Number of detections
01	A	10
01	B	11
01	C	8
02	A	13
02	B	9
03	A	7
03	B	12
03	C	11

What I'm going to do is process this a table to print the report and convert his data results to this form:

Table B

Date	a detection method	B Detection Method	C Method
01	10	11	8
02	13	9
03	7	12	11

2. Thinking:

It's a messy idea when you start doing it (in fact, it just comes up on a foreach loop and then you debug it). , wrote a few loops to find out seemingly can't, if can do, thank you very much you can leave a message we communicate together.

Then start looking at the relevant data and find that the C # operation DataTable can use a DataTable. Select ("column1=") to filter the data that you want to filter, conditions can have multiple, and the result returned is datarow[] collection.

Then look at the structure of table A, the date is duplicated, using datateble. Defaultview.todatatable (true,new string[] {"Column1"}) filters the data that needs to be filtered, which is equivalent to the distinct usage in SQL statements and can have more than one column.

Key syntax:

datarow[] Drarr = Datatable1.select ("clumn1= ' conditions '")//Conditionally query results
DataTable dt = DataTable1.DefaultView.ToTable (True, New string[] {"Column1"})//Filter data

3. Part of the code:

String a = "Select Car_zhdate,car_testtype,count (0) detect the number of detected methods per day from Tj_car_testtype GROUP by Car_zhdate,car_testtype or Der by Car_zhdate,car_testtype "//daily detection methods to detect how many cars string b =" Select A.car_zhdate, the first inspection of the number of days, the total number of initial inspection, ISNULL (each day Retest qualified quantity, 0 each day recheck qualified quantity, IsNull (each day recheck total quantity, 0) each day recheck total quantity from "+" (select Car_zhdate,count (0) each day first examines the qualified quantity fro
                            M tj_car_testtype where car_evl= ' T ' and Car_ccdate=car_zhdate and car_rettest= ' 1 ' GROUP by car_zhdate) a ' + "Left join" + "(select Car_zhdate,count (0) Total number of first checks from Tj_car_testtype where Car_ccdate=car_zhdate and car_rettest= ' 1 ' GROUP by car_zhdate) B "+" on a.car_zhdate = b.ca R_zhdate "+" LEFT Join "+" (select Car_zhdate,count (0) The number of days of retest qualified
                            From Tj_car_testtype where car_evl= ' T ' and Car_ccdate=car_zhdate and car_rettest= ' 2 ' GROUP by car_zhdate ' C ' + "On A.CAr_zhdate=c.car_zhdate "+" LEFT Join "+" (select Car_zhdate,coun
                            T (0) Total number of retest days from Tj_car_testtype where Car_ccdate=car_zhdate and car_rettest= ' 2 ' GROUP by car_zhdate) d "+

                "On A. Car_zhdate=d.car_zhdate"; DataTable AA = SqlHelper.ExecuteDataset (CommandType.Text, a).
                Tables[0]; DataTable BB = SqlHelper.ExecuteDataset (CommandType.Text, b).

                Tables[0];
                DataTable tempdb = new DataTable (); Tempdb.
                Columns.Add ("Ri", typeof (String)); Tempdb.
                Columns.Add ("ASM", typeof (String)); Tempdb.
                Columns.Add ("SDS", typeof (String)); Tempdb.
                Columns.Add ("BTG", typeof (String)); Tempdb.
                Columns.Add ("Sub", typeof (String)); Tempdb.
                Columns.Add ("Cjhgl", typeof (String)); Tempdb.

                Columns.Add ("Fjhgl", typeof (String)); String sub = ""; String cjhgl = ""; StringFjhgl = ""; foreach (DataRow Dr in Bb.) Rows) {sub = convert.tostring (Convert.ToInt32 (dr["Total number of initial checks]". ToString ()) + Convert.ToInt32 (dr["Total number of Days of review"].
                    ToString ())); Cjhgl = (Convert.todecimal (dr["The number of initial inspection of each day"). ToString ())/Convert.todecimal (dr["Total number of initial checks per day"]. ToString ())).
                    ToString ("P"); if (dr["total number of Days of review"].
                    ToString () = = "0") {Fjhgl = "no retest vehicle"; else {Fjhgl = (Convert.todecimal (dr["eligible quantity for each day"). ToString ())/Convert.todecimal (dr["Total number of Days of review"]. ToString ())).

                    ToString ("P"); } tempdb.
                Rows.Add ("", "", "", "", Sub, Cjhgl, FJHGL); } datarow[] Sdsarr; Datarow[] Asmarr;
                Datarow[] Btgarr; DataTable ritable = aa.
                Defaultview.totable (True, new string[] {"Car_zhdate"}); int ricount = ritable. Rows.coUnt for (int i = 0; i < Ricount i++) {Sdsarr = AA. Select ("car_zhdate= '" + ritable.) rows[i]["Car_zhdate"].
                    ToString () + "' and car_testtype= ' 0 '"); Asmarr = AA. Select ("car_zhdate= '" + ritable.) rows[i]["Car_zhdate"].
                    ToString () + "' and car_testtype= ' 1 '"); Btgarr = AA. Select ("car_zhdate= '" + ritable.) rows[i]["Car_zhdate"].
                    ToString () + "' and car_testtype= ' 4 '"); Tempdb. Rows[i]["ri"] = ritable. rows[i]["Car_zhdate"].
                    ToString (); if (Sdsarr. Length > 0) tempdb. rows[i]["SDS"] = sdsarr[0]["Number of detection methods per day"].
                    ToString (); else tempdb.
                    rows[i]["SDS"] = "0"; if (Asmarr. Length > 0) tempdb. rows[i]["asm"] = asmarr[0]["Number of detection methods per day"].
                    ToString (); else tempdb.
                    rows[i]["asm"] = "0"; If(Btgarr. Length > 0) tempdb. rows[i]["BTG"] = btgarr[0]["Number of detection methods per day"].
                    ToString (); else tempdb.
                rows[i]["BTG"] = "0"; }