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  • Removing "Using temporary; Using filesort" from this MySQL select+join+group by query

    - by claytontstanley
    I have the following query: select t.Chunk as LeftChunk, t.ChunkHash as LeftChunkHash, q.Chunk as RightChunk, q.ChunkHash as RightChunkHash, count(t.ChunkHash) as ChunkCount from chunksubset as t join chunksubset as q on t.ID = q.ID group by LeftChunkHash, RightChunkHash And the following explain table: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subsets ref PRIMARY,IDIndex,SubsetIndex SubsetIndex 767 const 522014 "Using where; Using temporary; Using filesort" 1 SIMPLE subsets eq_ref PRIMARY,IDIndex,SubsetIndex PRIMARY 771 sotero.subsets.Id,const 1 "Using where; Using index" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 "Using where" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 note the "using temporary; using filesort". When this query is run, I quickly run out of RAM (presumably b/c of the temp table), and then the HDD kicks in, and the query slows to a halt. I thought it might be an index issue, so I started adding a few that sort of made sense: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment chunks 0 PRIMARY 1 ChunkId A 17796190 NULL NULL BTREE chunks 1 ChunkHashIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 IDIndex 1 Id A 1483015 NULL NULL BTREE chunks 1 ChunkIndex 1 Chunk A 243783 NULL NULL BTREE chunks 1 ChunkTypeIndex 1 ChunkType A 2 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 2 ChunkId A 17796190 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 2 ChunkType A 261708 NULL NULL BTREE chunks 1 chunkHashByIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByIDIndex 2 Id A 17796190 NULL NULL BTREE But still using the temporary table. The db engine is MyISAM. How can I get rid of the using temporary; using filesort in this query? Just changing to InnoDB w/o explaining the underlying cause is not a particularly satisfying answer. Besides, if the solution is to just add the proper index, then that's much easier than migrating to another db engine.

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  • java api design - NULL or Exception

    - by srini.venigalla
    Is it better to return a null value or throw an exception from an API method? Returning a null requires ugly null checks all over, and cause a major quality problem if the return is not checked. Throwing an exception forces the user to code for the faulty condition, but since Java exceptions bubble up and force the caller code to handle them, in general, using custom exceptions may be a bad idea (specifically in java). Any sound and practical advice?

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  • SQL for sorting boolean column as true, null, false

    - by petehern
    My table has three boolean fields: f1, f2, f3. If I do SELECT * FROM table ORDER BY f1, f2, f3 the records will be sorted by these fields in the order false, true, null. I wish to order them with null in between true and false: the correct order should be true, null, false. I am using PostgreSQL.

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  • removing null valued columns from dataset in asp .net

    - by N.Sai Harish
    I have a table which stores data with null valued columns for some entries .I want to retrieve only Not null data to the detail view. I tried the following foreach(string strTableField in (objDataSet.Tables[0].Columns[i])) { if(objDataSet.Tables[0].Columns[i].Equals(null)) { objDataSet.Tables[0].Columns.Remove(strTableField); objDataSet.Tables[0].AcceptChanges(); } i++; } but it is giving error .. Pls help me reg this ...

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  • Web Service returning object with null fields

    - by Xaiter
    Never seen this one before. WebService.Implementation imp = new WebService.Implementation(); WebService.ImplementationRequest req = new WebService.ImplementationRequest(); return imp.GetValue(req); The object that imp returns is not null. It's returning an ImplementationResponse, as expected. But all of the fields in that object are null. Which is not expected. The WebService, currently, just returns some constant dummy data. We've tested this on another developer's machine, works just fine. I suppose I should also note that the WebService should throw an exception if I pass null into the GetValue method. It doesn't. Not for me. Any idea what could be wrong with my environment that could make a WebService return an object, but make every value in that object null? And somehow 'magically' return this mystery object when it should be throwing an exception?

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  • C Programming - Passing a pointer to array

    - by Pedro
    How do I pass a pointer value to an array of the struct; For example, on a txt I have this: John Doe;[email protected];214425532; My code: typedef struct Person{ char name[100]; char email[100]; int phone; }PERSON; int main(){ PERSON persons[100]; FILE *fp; char *ap_name; char *ap_email; char *ap_phone; char line[100]; fp=("text.txt","r"); if(fp==NULL){ exit(1); } else{ fgets(line,100,fp); ap_name=strtok(line,";"); ap_email=strtok(NULL,";"); ap_phone=strtok(NULL,";"); } return 0; } My question is how can I pass the value of ap_name, ap_email, ap_phone to the struct? And, do I need to use all of these pointers?

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  • How to find an element in an array in C

    - by gkaykck
    I am trying to find the location of an element in the array. I have tried to use this code i generated for(i=0;i<10;i++) { if (strcmp(temp[0],varptr[i])==0) j=i; } varptr is a pointer which points to array var[11][10] and it is by the definition *varptr[11][10]. I have assigned strings to var[i] and i want to get the "i" number of my element NOT THE ADRESS. Thanks for any comment. EDit: temp is also a pointer which points to the string that i want to check. Also i am using the 2D array for keeping variable names and their address. So yes i want to keep it inside a 2D array. The question is this code is not working at all, it does not assigns i to j, so i wonder where is the problem with this idea? writing a "break" does not change if the code works or not, it just optimizes the code a little. Full Code: #include <stdio.h> #include <string.h> #include <ctype.h> double atof(char*); int main(void) { char in[100], *temp[10],var[11][10],*varptr[11][10]; int i,j, n = 0,fullval=0; double val[11]; strcpy(var[11], "ans"); for(i=0;i<11;i++) { for(j=0;j<10;j++) varptr[i][j]=&var[i][j]; } START: printf("Enter the expression: "); fflush(stdout); for(i=0;i<10;i++) temp[i]=NULL; if (fgets(in, sizeof in, stdin) != NULL) { temp[0] = strtok(in, " "); if (temp[0] != NULL) { for (n = 1; n < 10 && (temp[n] = strtok(NULL," ")) != NULL; n++) ; } if (*temp[0]=="quit") { goto FINISH;} if (isdigit(*temp[0])) { if (*temp[1]=='+') val[0] = atof(temp[0])+atof(temp[2]); else if (*temp[1]=='-') val[0] = atof(temp[0])-atof(temp[2]); else if (*temp[1]=='*') val[0] = atof(temp[0])*atof(temp[2]); else if (*temp[1]=='/') val[0] = atof(temp[0])/atof(temp[2]); printf("%s = %f\n",var[11],val[0]); goto START; } else if (temp[1]==NULL) //asking the value of a variable { for(i=0;i<10;i++) { if (strcmp(temp[0],varptr[i])==0) j=i; } printf("%s = %d\n",var[j],val[j]); goto START; } if (*temp[1]==61) { strcpy(var[fullval], temp[0]); if ((temp[3])!=NULL) { } val[fullval]=atof(temp[2]); printf("%s = %f\n",var[fullval],val[fullval]); fullval++; goto START; } if (*temp[1]!=61) { } } getch(); FINISH: return 0; }

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  • subscript requires array or pointer ERROR

    - by Kristian
    Hi, I know what is my mistake can't figer how to solve it. Im writing an winAPI that counts how many 'a' characters are found is a givien file. Im still getting the error " subscript requires array or pointer " (please find the comment in the code) #include "stdafx.h" #include <windows.h> int _tmain(int argc, _TCHAR* argv[]) { WCHAR str=L'a'; HANDLE A; TCHAR *fn; fn=L"d:\\test.txt"; A= CreateFile(fn,GENERIC_READ,0,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL); if(A==INVALID_HANDLE_VALUE) { _tprintf(L"cannot open file \n"); } else { DWORD really; int countletter; int stringsize; do { BYTE x[1024]; ReadFile(A,x,1024,&really,NULL); stringsize = sizeof(really); for(int i =0;i<stringsize;i++) { if(really[i]==str) //here Im getting the error countletter++; } }while(really==1024); CloseHandle(A); _tprintf(L"NUmbers of A's found is %d \n",countletter); } return 0; } now I know I can't make comparesion between array and a WCHAR but hw to fix it ?

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  • Combining two queries on same table

    - by user1830856
    I've looked through several previous questions but I am struggling to apply the solutions to my specific example. I am having trouble combining query 1 and query 2. My query originally returned (amongst other details) the values "SpentTotal" and "UnderSpent" for all members/users for the current month. My issue has been adding two additional columns to this original quert that will return JUST these two columns (Spent and Overspent) but for the previous months data Original Query #1: set @BPlanKey = '##CURRENTMONTH##' EXECUTE @RC = Minimum_UpdateForPeriod @BPlanKey SELECT cm.clubaccountnumber, bp.Description , msh.PeriodMinObligation, msh.SpentTotal, msh.UnderSpent, msh.OverSpent, msh.BilledDate, msh.PeriodStartDate, msh.PeriodEndDate, msh.OverSpent FROM MinimumSpendHistory msh INNER JOIN BillPlanMinimums bpm ON msh.BillingPeriodKey = @BPlanKey and bpm.BillPlanMinimumKey = msh.BillPlanMinimumKey INNER JOIN BillPlans bp ON bp.BillPlanKey = bpm.BillPlanKey INNER JOIN ClubMembers cm ON cm.parentmemberkey is null and cm.ClubMemberKey = msh.ClubMemberKey order by cm.clubaccountnumber asc, msh.BilledDate asc Query #2, query of all columns for PREVIOUS month, but I only need two (spent and over spent), added to the query from above, joined on the customer number: set @BPlanKeyLastMo = '##PREVMONTH##' EXECUTE @RCLastMo = Minimum_UpdateForPeriod @BPlanKeyLastMo SELECT cm.clubaccountnumber, bp.Description , msh.PeriodMinObligation, msh.SpentTotal, msh.UnderSpent, msh.OverSpent, msh.BilledDate, msh.PeriodStartDate, msh.PeriodEndDate, msh.OverSpent FROM MinimumSpendHistory msh INNER JOIN BillPlanMinimums bpm ON msh.BillingPeriodKey = @BPlanKeyLastMo and bpm.BillPlanMinimumKey = msh.BillPlanMinimumKey INNER JOIN BillPlans bp ON bp.BillPlanKey = bpm.BillPlanKey INNER JOIN ClubMembers cm ON cm.parentmemberkey is null and cm.ClubMemberKey = msh.ClubMemberKey order by cm.clubaccountnumber asc, msh.BilledDate asc Big thank you to any and all that are willing to lend their help and time. Cheers! AJ CREATE TABLE MinimumSpendHistory( [MinimumSpendHistoryKey] [uniqueidentifier] NOT NULL, [BillPlanMinimumKey] [uniqueidentifier] NOT NULL, [ClubMemberKey] [uniqueidentifier] NOT NULL, [BillingPeriodKey] [uniqueidentifier] NOT NULL, [PeriodStartDate] [datetime] NOT NULL, [PeriodEndDate] [datetime] NOT NULL, [PeriodMinObligation] [money] NOT NULL, [SpentTotal] [money] NOT NULL, [CurrentSpent] [money] NOT NULL, [OverSpent] [money] NULL, [UnderSpent] [money] NULL, [BilledAmount] [money] NOT NULL, [BilledDate] [datetime] NOT NULL, [PriorPeriodMinimum] [money] NULL, [IsCommitted] [bit] NOT NULL, [IsCalculated] [bit] NOT NULL, [BillPeriodMinimumKey] [uniqueidentifier] NOT NULL, [CarryForwardCounter] [smallint] NULL, [YTDSpent] [money] NOT NULL, [PeriodToAccumulateCounter] [int] NULL, [StartDate] [datetime] NOT NULL,

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  • Set reference = null in finally block?

    - by deamon
    A colleague of mine sets reference to null in finally blocks. I think this is nonsense. public Something getSomething() { JDBCConnection jdbc=null; try { jdbc=JDBCManager.getConnection(JDBCTypes.MYSQL); } finally { JDBCManager.free(jdbc); jdbc=null; // <-- Useful or not? } } What do you think of it?

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  • how can i substitute a NULL value for a 0 in an SQL Query result

    - by Name.IsNullOrEmpty
    SELECT EmployeeMaster.EmpNo, Sum(LeaveApplications.LeaveDaysTaken) AS LeaveDays FROM EmployeeMaster FULL OUTER JOIN LeaveApplications ON EmployeeMaster.id = LeaveApplications.EmployeeRecordID INNER JOIN LeaveMaster ON EmployeeMaster.id = LeaveMaster.EmpRecordID GRoup BY EmployeeMaster.EmpNo order by LeaveDays Desc with the above query, if an employee has no leave application record in table LeaveApplications, then their Sum(LeaveApplications.LeaveDaysTaken) AS LeaveDays column returns NULL. What i would like to do is place a value of 0 (Zero) instead of NULL. I want to do this because i have a calculated column in the same query whose formular depends on the LeaveDays returned and when LeaveDays is NULL, the formular some how fails. Is there away i can put 0 for NULL such that that i can get my desired result.

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  • Convert Yes/No/Null from SQL to True/False in a DataTable

    - by Scott Chamberlain
    I have a Sql Database (which I have no control over the schema) that has a Column that will have the varchar value of "Yes", "No", or it will be null. For the purpose of what I am doing null will be handled as No. I am programming in c# net 3.5 using a data table and table adapter to pull the data down. I would like to directly bind the column using a binding source to a check box I have in my program however I do not know how or where to put the logic to convert the string Yes/No/null to boolean True/False; Reading a null from the SQL server and writing back a No on a update is acceptable behavior. Any help is greatly appreciated. EDIT -- This is being developed for windows.

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  • C# 4: how to in-line detect for nulls?

    - by Dr. Zim
    In C# 4, wasn't there a short cut for checking for null values like so: if( myobject?.myproperty?.myotherproperty?.value != null ) The value would return null and not throw an exception. Anyone have a link to how to use it or at least the syntax?

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  • JQUERY ajax passing null value from MVC View to Controller

    - by Piyush Sardana
    hi guys i'm posting some data to controller using jquery ajax, but i am getting null values in my controller, jQuery code is: $('#registerCompOff').click(function() { var compOff = []; $('div').each(function() { var curRow = {}; curRow.Description = $(this).find('.reason').val(); curRow.CompOffDate = $(this).find('.datefieldWithWeekends').val(); if (curRow.Description != null && curRow.CompOffDate != null) { compOff.push(curRow); } }); $.ajax({ type: 'POST', url: this.href, dataType: 'json', data: compOff }); return $('form').valid(); });? compOff is not null I have checked that... controller is: [HttpPost] public ActionResult RegisterCompOff(RegisterCompOff[] registerCompOff) { //return View(); } can you tell me where i'm going wrong?

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  • PreparedStatement and 'null' value in WHERE clause

    - by bond
    I am using PrepareStatement and BatchUpdate for executimg a UPDATE query. In for loop I create a Batch. At end of loop I execute batch. Above logic works fine if SQL query used in PrepareStatement does not have null values in WHERE claues. Update Statement fails if there is null value in WHERE clasue. My code looks something like this, connection = getConnection(); PreparedStatement ps = connection.prepareStatement("UPDATE TEST_TABLE SET Col1 = true WHERE Col2 = ? AND Col3 = ?") for (Data aa : InComingData) { if(null == aa.getCol2()) { ps.setNull(1, java.sql.Types.INTEGER); } else { ps.setInteger(1,aa.getCol2()) } if(null == aa.getCol3()) { ps.setNull(2, java.sql.Types.INTEGER); } else { ps.setInteger(2,aa.getCol3()) } ps.addBatch(); } ps.executeBatch(); connection.commit(); Any help would be appreciated.

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  • Cant get JavaScipt to check for null objects

    - by CountMurphy
    I really don't know what the issue is here. Far as I can see, the code is simple and should work fine. var Prices=""; for (var PriceCount = 1; PriceCount <= 120; PriceCount++) { var CurrentPrice = "Price" + PriceCount; if (prevDoc.getElementById(CurrentPrice).value != null) { if (Prices == "") { Prices = prevDoc.getElementById(CurrentPrice).value; } else { Prices += "," + prevDoc.getElementById(CurrentPrice).value; } } else { break; } } There could be up to 120 hidden inputs on the form. The moment we check for an input that doesn't exist the loop should break. My test page has two input elements that get pulled. On the third (the null) I get this error in firebug: prevDoc.getElementById(CurrentPrice) is null if (prevDoc.getElementById(CurrentPrice).value != null) { Yes it is null...that's what the check is for ?_? Does any one know what I'm doing wrong? This seems like it should be really straight forward. EDIT: for clarity's sake, prevDoc=window.opener.document

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  • Drupal Views: Render Null Result for Relationship as 0

    - by Kyle S
    I have a View configured in Drupal to return nodes, sorting them by their average vote in descending order. For the purpose of the View, the value of the average votes is a Relationship. I noticed that nodes with no votes are displayed after nodes with a negative average. Nodes with no votes should have an average of 0, but I believe the MySQL JOIN is causing NULL values to be returned (as there are no matching rows in the joined table, since a row is created after the first vote is cast for that item). I discovered that with MySQL it is possible to output all values that are NULL in a column as another value with IFNULL(column_name,'other value'). I feel like I would need to modify the Views module in order to obtain this functionality, but I'm hoping that there is some sort of option that returns NULL values in a relation (a relation doesn't exist for the item) as 0 instead of NULL, so that I can properly sort the nodes. The modules I am using include Views, Voting API, Vote Up/Down, and CTools. Thanks.

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  • Whether to check for null

    - by coffeeaddict
    I know that you should always check incoming params to a method for null. But what if I have this scenario with a try/catch referring to a local variable. Do I really need to check for null below? Because it's gonna catch it anyway if it's null and the next line of code tries to use the refundResponse variable: public string DoRefund(...) { try { ...... string refundTransactionID = string.Empty; ...... RefundTransactionResponseType refundResponse = transaction.DoRefund(...); if (refundResponse != null) refundTransactionID = refundResponse.RefundTransactionID; ..... } catch (Exception ex) { LogError(ex); return ex.ToString(); } }

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  • Not getting concept of null

    - by appu
    Hy Guys, Beginning with mysql. I am not able to grasp the concept of NULL. Check screen-shot (*declare_not_null, link*). In it when I specifically declared 'name' field to be NOT NULL. When i run the 'desc test' table command, the table description shows default value for name field to be NULL.Why is that so? From what I have read about NULL, it connotes a missing or information that is not applicable. So when I declare a field to be NOT NULL it implies (as per my understanding) that user must enter a value for the name field else the DB engine should generate an error i.e. record will not be entered in DB. However when i run 'insert into test value();' the DB engine enters the record in table. Check screen-shot(*empty_value, link*). FLICKR LINKS *declare_not_null* http://www.flickr.com/photos/55097319@N03/5302758813/ *empty_values* Check the second screenshot on flickr Q.2 what would be sql statemetn to drop a primary key from a table's field. If I use 'ALTER TABLE test drop key id;' it gives the following: ERROR: Incorrect table definition; there can be only one auto column and it must be defined as a key. Thanks for your help..

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