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  • SQL SERVER – Using MAXDOP 1 for Single Processor Query – SQL in Sixty Seconds #008 – Video

    - by pinaldave
    Today’s SQL in Sixty Seconds video is inspired from my presentation at TechEd India 2012 on Speed up! – Parallel Processes and Unparalleled Performance. There are always special cases when it is about SQL Server. There are always few queries which gives optimal performance when they are executed on single processor and there are always queries which gives optimal performance when they are executed on multiple processors. I will be presenting the how to identify such queries as well what are the best practices related to the same. In this quick video I am going to demonstrate if the query is giving optimal performance when running on single CPU how one can restrict queries to single CPU by using hint OPTION (MAXDOP 1). More on Errors: Difference Temp Table and Table Variable – Effect of Transaction Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT Debate – Table Variables vs Temporary Tables – Quiz – Puzzle – 13 of 31 I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Video

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  • “Query cost (relative to the batch)” <> Query cost relative to batch

    - by Dave Ballantyne
    OK, so that is quite a contradictory title, but unfortunately it is true that a common misconception is that the query with the highest percentage relative to batch is the worst performing.  Simply put, it is a lie, or more accurately we dont understand what these figures mean. Consider the two below simple queries: SELECT * FROM Person.BusinessEntity JOIN Person.BusinessEntityAddress ON Person.BusinessEntity.BusinessEntityID = Person.BusinessEntityAddress.BusinessEntityID go SELECT * FROM Sales.SalesOrderDetail JOIN Sales.SalesOrderHeader ON Sales.SalesOrderDetail.SalesOrderID = Sales.SalesOrderHeader.SalesOrderID After executing these and looking at the plans, I see this : So, a 13% / 87% split ,  but 13% / 87% of WHAT ? CPU ? Duration ? Reads ? Writes ? or some magical weighted algorithm ?  In a Profiler trace of the two we can find the metrics we are interested in. CPU and duration are well out but what about reads (210 and 1935)? To save you doing the maths, though you are more than welcome to, that’s a 90.2% / 9.8% split.  Close, but no cigar. Lets try a different tact.  Looking at the execution plan the “Estimated Subtree cost” of query 1 is 0.29449 and query 2 its 1.96596.  Again to save you the maths that works out to 13.03% and 86.97%, round those and thats the figures we are after.  But, what is the worrying word there ? “Estimated”.  So these are not “actual”  execution costs,  but what’s the problem in comparing the estimated costs to derive a meaning of “Most Costly”.  Well, in the case of simple queries such as the above , probably not a lot.  In more complicated queries , a fair bit. By modifying the second query to also show the total number of lines on each order SELECT *,COUNT(*) OVER (PARTITION BY Sales.SalesOrderDetail.SalesOrderID) FROM Sales.SalesOrderDetail JOIN Sales.SalesOrderHeader ON Sales.SalesOrderDetail.SalesOrderID = Sales.SalesOrderHeader.SalesOrderID The split in percentages is now 6% / 94% and the profiler metrics are : Even more of a discrepancy. Estimates can be out with actuals for a whole host of reasons,  scalar UDF’s are a particular bug bear of mine and in-fact the cost of a udf call is entirely hidden inside the execution plan.  It always estimates to 0 (well, a very small number). Take for instance the following udf Create Function dbo.udfSumSalesForCustomer(@CustomerId integer) returns money as begin Declare @Sum money Select @Sum= SUM(SalesOrderHeader.TotalDue) from Sales.SalesOrderHeader where CustomerID = @CustomerId return @Sum end If we have two statements , one that fires the udf and another that doesn't: Select CustomerID from Sales.Customer order by CustomerID go Select CustomerID,dbo.udfSumSalesForCustomer(Customer.CustomerID) from Sales.Customer order by CustomerID The costs relative to batch is a 50/50 split, but the has to be an actual cost of firing the udf. Indeed profiler shows us : No where even remotely near 50/50!!!! Moving forward to window framing functionality in SQL Server 2012 the optimizer sees ROWS and RANGE ( see here for their functional differences) as the same ‘cost’ too SELECT SalesOrderDetailID,SalesOrderId, SUM(LineTotal) OVER(PARTITION BY salesorderid ORDER BY Salesorderdetailid RANGE unbounded preceding) from Sales.SalesOrderdetail go SELECT SalesOrderDetailID,SalesOrderId, SUM(LineTotal) OVER(PARTITION BY salesorderid ORDER BY Salesorderdetailid Rows unbounded preceding) from Sales.SalesOrderdetail By now it wont be a great display to show you the Profiler trace reads a *tiny* bit different. So moral of the story, Percentage relative to batch can give a rough ‘finger in the air’ measurement, but dont rely on it as fact.

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  • optimize query: get al votes from user's item

    - by Toni Michel Caubet
    hi there! i did it my way because i'm very bad getting results from two tables... Basically, first i get all the id items that correspond to the user, and then i calculate the ratings of each item. But, there is two different types of object item, so i do this 2 times: show you: function votos_usuario($id){ $previa = "SELECT id FROM preguntas WHERE id_usuario = '$id'"; $r_previo = mysql_query($previa); $ids_p = '0, '; while($items_previos = mysql_fetch_array($r_previo)){ $ids_p .= $items_previos['id'].", "; //echo "ids pregunta usuario: ".$items_previos['id']."<br>"; } $ids = substr($ids_p,0,-2); //echo $ids; $consulta = "SELECT valor FROM votos_pregunta WHERE id_pregunta IN ( $ids )"; //echo $consulta; $resultado = mysql_query($consulta); $votos_preguntas = 0; while($voto = mysql_fetch_array($resultado)){ $votos_preguntas = $votos_preguntas + $voto['valor']; } $previa_r = "SELECT id FROM recetas WHERE id_usuario = '$id'"; $r_previo_r = mysql_query($previa_r); $ids_r = '0, '; while($items_previos_r = mysql_fetch_array($r_previo_r)){ $ids_r .= $items_previos_r['id'].", "; //echo "ids pregunta usuario: ".$items_previos['id']."<br>"; } $ids = substr($ids_r,0,-2); $consulta_b = "SELECT valor FROM votos_receta WHERE id_receta IN ( $ids )"; //echo $consulta; $resultado_b = mysql_query($consulta_b); $votos_recetas = 0; while($voto_r = mysql_fetch_array($resultado_b)){ $votos_recetas = $votos_recetas + $voto_r['valor']; } $total = $votos_preguntas + $votos_recetas; return $total; } As you can si this is two much.. O(n^2) Feel like thinking? thanks!

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  • Query not returning rows in a table that don't have corresponding values in another [associative] ta

    - by Obay
    I have Table: ARTICLES ID | CONTENT --------------- 1 | the quick 2 | brown fox 3 | jumps over 4 | the lazy Table: WRITERS ID | NAME ---------- 1 | paul 2 | mike 3 | andy Table: ARTICLES_TO_WRITERS ARTICLE_ID | WRITER_ID ----------------------- 1 | 1 2 | 2 3 | 3 To summarize, article 4 has no writer. So when I do a "search" for articles with the word "the": SELECT a.id, a.content, w.name FROM articles a, writers w, articles_to_writers atw WHERE a.id=atw.article_id AND w.id=atw.writer_id AND content LIKE '%the%' article 4 does not show up in the result: ID | CONTENT | NAME ----------------------- 1 | the quick | paul How do I make article 4 still appear in the results even though it has no writers?

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  • Optimize MYSQL Query with Order by

    - by Victor
    Hello, I have seen mysql queries with order by runs slow. Is there any specific way to optimize queries which use order by ? Queries without order by run very fast but with order by its always runs slow. if any one suggest any thing on this as general solutions. Thank You

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  • How to optimize this user ranking query

    - by James Simpson
    I have 2 databases (users, userRankings) for a system that needs to have rankings updated every 10 minutes. I use the following code to update these rankings which works fairly well, but there is still a full table scan involved which slows things down with a few hundred thousand users. mysql_query("TRUNCATE TABLE userRankings"); mysql_query("INSERT INTO userRankings (userid) SELECT id FROM users ORDER BY score DESC"); mysql_query("UPDATE users a, userRankings b SET a.rank = b.rank WHERE a.id = b.userid"); In the userRankings table, rank is the primary key and userid is an index. Both tables are MyISAM (I've wondered if it might be beneficial to make userRankings InnoDB).

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  • Query Tuning Mastery at PASS Summit 2012: The Video

    - by Adam Machanic
    An especially clever community member was kind enough to reverse-engineer the video stream for me, and came up with a direct link to the PASS TV video stream for my Query Tuning Mastery: The Art and Science of Manhandling Parallelism talk, delivered at the PASS Summit last Thursday. I'm not sure how long this link will work , but I'd like to share it for my readers who were unable to see it in person or live on the stream. Start here. Skip past the keynote, to the 149 minute mark. Enjoy!...(read more)

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  • Access VBA sub with form as parameter doesn't alter the form

    - by Ski
    I have a Microsoft Access 2003 file with various tables of data. Each table also has a duplicate of it, with the name '[original table name]_working'. Depending on the user's choices in the switchboard, the form the user choose to view must switch its recordsource table to the working table. I refactored the relevant code to do such a thing into the following function today: Public Sub SetFormToWorking(ByRef frm As Form) With frm .RecordSource = rst![Argument] & "_working" .Requery Dim itm As Variant For Each itm In .Controls If TypeOf itm Is subForm Then With Item Dim childFields As Variant, masterFields As Variant childFields = .LinkChildFields masterFields = .LinkMasterFields .Form.RecordSource = .Form.RecordSource & "_working" .LinkChildFields = childFields .LinkMasterFields = masterFields .Form.Requery End With End If Next End With End Sub The lines of code that call the function look like this: SetFormToWorking Forms(rst![Argument]) and SetFormToWorking Forms(cmbTblList) For some reason, the above function doesn't change the recordsource for the form. I added the 'ByRef' keyword to the parameter just to be certain that it was passing by reference, but no dice. Hopefully someone here can tell me what I've done wrong?

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  • Query Tuning Mastery at PASS Summit 2012: The Video

    - by Adam Machanic
    An especially clever community member was kind enough to reverse-engineer the video stream for me, and came up with a direct link to the PASS TV video stream for my Query Tuning Mastery: The Art and Science of Manhandling Parallelism talk, delivered at the PASS Summit last Thursday. I'm not sure how long this link will work , but I'd like to share it for my readers who were unable to see it in person or live on the stream. Start here. Skip past the keynote, to the 149 minute mark. Enjoy!...(read more)

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  • Query Tuning Mastery at PASS Summit 2012: The Demos

    - by Adam Machanic
    For the second year in a row, I was asked to deliver a 500-level "Query Tuning Mastery" talk in room 6E of the Washington State Convention Center, for the PASS Summit. ( Here's some information about last year's talk, on workspace memory. ) And for the second year in a row, I had to deliver said talk at 10:15 in the morning, in a room used as overflow for the keynote, following a keynote speaker that didn't stop speaking on time. Frustrating! Last Thursday, after very, very quickly setting up and...(read more)

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  • Converting sql query to EF query - nested query in from

    - by vdh_ant
    Hey guys Just wondering how the following sql query would look in linq for Entity Framework... SELECT KPI.* FROM KeyPerformanceIndicator KPI INNER JOIN ( SELECT SPP.SportProgramPlanId FROM SportProgramPlan PSPP INNER JOIN SportProgramPlan ASPP ON (PSPP.SportProgramPlanId = @SportProgramPlanId AND PSPP.StartDate >= ASPP.StartDate AND PSPP.EndDate <= ASPP.EndDate ) AS SPP ON KPI.SportProgramPlanId = SPP.SportProgramPlanId Cheers Anthony

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  • Figuring a max repetitive sub-tree in an object tree

    - by bonomo
    I am trying to solve a problem of finding a max repetitive sub-tree in an object tree. By the object tree I mean a tree where each leaf and node has a name. Each leaf has a type and a value of that type associated with that leaf. Each node has a set of leaves / nodes in certain order. Given an object tree that - we know - has a repetitive sub-tree in it. By repetitive I mean 2 or more sub-trees that are similar in everything (names/types/order of sub-elements) but the values of leaves. No nodes/leaves can be shared between sub-trees. Problem is to identify these sub-trees of the max height. I know that the exhaustive search can do the trick. I am rather looking for more efficient approach.

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  • Sub-query problem on Oracle 10g

    - by Eric
    The following query works on Oracle 10.2.0.1.0 on windows,but doesn't work on Oracle 10.2.0.2.0 on Linux. What's the problem?How can I make it work? Thanks! CREATE TABLE AUDITHISTORY( CASENUM numeric(20, 0) NOT NULL, AUDIT_DATE date NOT NULL, USER_NAME varchar(255) NULL, AUDIT_USECS numeric(6, 0) NOT NULL ) Query: SELECT T.CASENUM, T.USER_NAME, T.AUDIT_DATE AS STARTED, (SELECT * FROM (SELECT S.AUDIT_DATE FROM AUDITHISTORY S WHERE S.CASENUM=T.CASENUM AND S.USER_NAME=T.USER_NAME AND (S.AUDIT_DATE > T.AUDIT_DATE OR (S.AUDIT_DATE = T.AUDIT_DATE AND S.AUDIT_USECS > T.AUDIT_USECS)) ORDER BY S.AUDIT_DATE ASC,S.AUDIT_USECS ASC ) WHERE rownum <= 1) AS ENDED FROM AUDITHISTORY T BANNER Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod PL/SQL Release 10.2.0.1.0 - Production CORE 10.2.0.1.0 Production TNS for 32-bit Windows: Version 10.2.0.1.0 - Production NLSRTL Version 10.2.0.1.0 - Production BANNER Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - Prod PL/SQL Release 10.2.0.2.0 - Production CORE 10.2.0.2.0 Production TNS for Linux: Version 10.2.0.2.0 - Production NLSRTL Version 10.2.0.2.0 - Production

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  • SQL SERVER – Denali Feature – Zoom Query Editor

    - by pinaldave
    SQL Server next version ‘Denali’ is coming up with very neat feature which can be used while presentations, group discussion or for people who prefers large fonts. I have increased the font size to 400 percentage and for the same reason they are very large. You can adjust the font size which is convenient to you. One more reason to go for next version of SQL Server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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  • Adding an LOV to a query parameter (executeWithParams)

    - by shay.shmeltzer
    I showed in the past how you can use the executeWithParams operation to build your own query page to filter a view object to show specific rows. I also showed how you can make the parameter fields display as drop down lists of values (selectOneChoice). However this week someone asked me if you can have those parameter fields use the advanced LOV component. Well if you just try and drag the parameter over, you'll see that the LOV option is not there as a drop option. But with a little bit of hacking around you can achieve this. (without actual Java coding). Here is a quick demo:

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  • How can I join this 2 queries?(A select query with join and An unpivot query)

    - by MANG KANOR
    Here are my two queries SELECT EWND.Position, NKey = CASE WHEN ISNULL(Translation.Name, '') = '' THEN EWND.Name ELSE Translation.Name END, Unit = EW_N_DEF.Units FROM EWND INNER JOIN EW_N_DEF ON EW_N_DEF.Nutr_No = EWND.Nutr_No LEFT JOIN Translation ON Translation.CodeMain = EWND.Nutr_no WHERE Translation.CodeTrans = 1 ORDER BY EWND.Position And this is the unpivot one SELECT * FROM (SELECT N1,N2,N3,N4,N5,N6,N7,N8,N9,N10,N11,N12,N13,N14,N15,N16,N17,N18,N19,N20,N21,N22,N23,N24,N25,N26,N27,N28,N29,N30,N31,N32,N33,N34 FROM EWNVal WHERE Code=6035) Test UNPIVOT (Value FOR NUTCODE IN (N1,N2,N3,N4,N5,N6,N7,N8,N9,N10,N11,N12,N13,N14,N15,N16,N17,N18,N19,N20,N21,N22,N23,N24,N25,N26,N27,N28,N29,N30,N31,N32,N33,N34) )AS test Both Queries put out same number of rows but not columns, Is it possible to join this two? I tried the union but it has problems that I cant solve Thanks in advance!

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  • T-SQL Tuesday #13: Clarifying Requirements

    - by Alexander Kuznetsov
    When we transform initial ideas into clear requirements for databases, we typically have to make the following choices: Frequent maintenance vs doing it once. As we are clarifying the requirements, we need to determine whether we want to concinue spending considerable time maintaining the system, or if we want to finish it up and move on to other tasks. Race car maintenance vs installing electric wiring is my favorite analogy for this kind of choice. In some cases we need to sqeeze every last bit...(read more)

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  • Howto UML: sub methods / calls / operations / procedures

    - by hsmit
    How would you guys model this in UML (in a sequence diagram)? .. car1.drive(); .. ... in Car class: .. drive(){ this.startEngine(); } startEngine(){ this.getKey(); this.insertKey(); } .. a small begin: objx car1 ---- ---- | | | drive() | |-------->| startEngine() | |------------. | | | | |<-----------. | | But where comes the getKey() method? Must this be communicated via another sequence diagram? Or is there a way to include sub procedures?

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  • Mysql - What's wrong with the query...?

    - by SpikETidE
    Hi everybody.... I am trying to query a database to find the following If a customer searches for a hotel in a city between dates A and B, find and return the hotels in which rooms are free between the two dates. There will be more than one room in each room type(i.e. 5 Rooms in type A, 10 rooms in Type B etc) and we have to query the db to find only those hotels in which there is atleast one room free in atleast one type. This is my table structure.... **Structure for table 'reservations'** reservation_id hotel_id room_id customer_id payment_id no_of_rooms check_in_date check_out_date reservation_date **Structure for table 'hotels'** hotel_id hotel_name hotel_description hotel_address hotel_location hotel_country hotel_city hotel_type hotel_stars hotel_image hotel_deleted **Structure for table 'rooms'** room_id hotel_id room_name max_persons total_rooms room_price room_image agent_commision room_facilities service_tax vat city_tax room_description room_deleted And this is my query $city_search = '15'; $check_in_date = '29-03-2010'; $check_out_date = '31-03-2010'; $dateFormat_check_in = "DATE_FORMAT('$reservations.check_in_date','%d-%m-%Y')"; $dateFormat_check_out = "DATE_FORMAT('$reservations.check_out_date','%d-%m-%Y')"; $dateCheck = "$dateFormat_check_in >= '$check_in_date' AND $dateFormat_check_out <= '$check_out_date'"; $query = "SELECT $rooms.room_id, $rooms.room_name, $rooms.max_persons, $rooms.room_price, $hotels.hotel_id, $hotels.hotel_name, $hotels.hotel_stars, $hotels.hotel_type FROM $hotels,$rooms,$reservations WHERE $hotels.hotel_city = '$city_search' AND $hotels.hotel_id = $rooms.hotel_id AND $hotels.hotel_deleted = '0' AND $rooms.room_deleted = '0' AND $rooms.total_rooms - (SELECT SUM($reservations.no_of_rooms) as tot FROM $reservations WHERE $dateCheck GROUP BY $reservations.room_id) > '0'"; The number of rooms already reserved in each room type in each hotel will be stored in the reservations table... The thing is the query doesn't return any result at all...even though it should if i calculate it myself manually... I tried running the sub-query alone and i don't get any result... And i have lost quite some amount of hair trying to de-bug this query from yesterday... What's wrong with this...? Or is there a better way to do what i mentioned above...? Thanks for your time... Edit : Code edited to remove an bud... thanks to

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  • Redirect/rewrite dynamic URL to sub-domain and create DNS for subdomain

    - by Abdul Majeed
    I have created an application in PHP, I would like to re-direct the following URL to corresponding sub-domain. Dynamic URL pattern: http://mydomain.com/mypage.php?user_name=testuser I wish to re-direct this to the corresponding sub domain: http://testuser.mydomain.com/ How do I create a rewrite rule for this purpose? How do I register DNS for sub-domain without using CPANEL? (I want to activate sub-domain when the user registers to the system.)

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  • htaccess to redirect from domain with sub-directory url to the same url on sub-domain

    - by Ibrahm Yaser
    i have problem of redirecting from domain with sub-directory like http://mydomain.com/project/01/117q803789s92d01 or http://mydomain.com/project/08/117t803789s92d08 .. etc to always http://ww2.mydomain.com/project/01/117q803789s92d01 the other link will to http://ww2.mydomain.com/project/08/117t803789s92d08 ... etc i tried this RewriteCond %{HTTP_HOST} ^mydomain\.com$ [OR] RewriteCond %{HTTP_HOST} ^www\.mydomain\.com$ RewriteRule ^project\/\/?(.*)$ "http\:\/\/ww2\.mydomain\.com\/project\/$1" [R=301,L] but for some reason its always redirect me to wrong with missing "\" like if i try to access http://mydomain.com/project/01/117q803789s92d01 redirect me to http://ww2.mydomain.com/project01/117q803789s92d01 Did I miss something?!

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  • Function Folding in #PowerQuery

    - by Darren Gosbell
    Originally posted on: http://geekswithblogs.net/darrengosbell/archive/2014/05/16/function-folding-in-powerquery.aspxLooking at a typical Power Query query you will noticed that it's made up of a number of small steps. As an example take a look at the query I did in my previous post about joining a fact table to a slowly changing dimension. It was roughly built up of the following steps: Get all records from the fact table Get all records from the dimension table do an outer join between these two tables on the business key (resulting in an increase in the row count as there are multiple records in the dimension table for each business key) Filter out the excess rows introduced in step 3 remove extra columns that are not required in the final result set. If Power Query was to execute a query like this literally, following the same steps in the same order it would not be overly efficient. Particularly if your two source tables were quite large. However Power Query has a feature called function folding where it can take a number of these small steps and push them down to the data source. The degree of function folding that can be performed depends on the data source, As you might expect, relational data sources like SQL Server, Oracle and Teradata support folding, but so do some of the other sources like OData, Exchange and Active Directory. To explore how this works I took the data from my previous post and loaded it into a SQL database. Then I converted my Power Query expression to source it's data from that database. Below is the resulting Power Query which I edited by hand so that the whole thing can be shown in a single expression: let     SqlSource = Sql.Database("localhost", "PowerQueryTest"),     BU = SqlSource{[Schema="dbo",Item="BU"]}[Data],     Fact = SqlSource{[Schema="dbo",Item="fact"]}[Data],     Source = Table.NestedJoin(Fact,{"BU_Code"},BU,{"BU_Code"},"NewColumn"),     LeftJoin = Table.ExpandTableColumn(Source, "NewColumn"                                   , {"BU_Key", "StartDate", "EndDate"}                                   , {"BU_Key", "StartDate", "EndDate"}),     BetweenFilter = Table.SelectRows(LeftJoin, each (([Date] >= [StartDate]) and ([Date] <= [EndDate])) ),     RemovedColumns = Table.RemoveColumns(BetweenFilter,{"StartDate", "EndDate"}) in     RemovedColumns If the above query was run step by step in a literal fashion you would expect it to run two queries against the SQL database doing "SELECT * …" from both tables. However a profiler trace shows just the following single SQL query: select [_].[BU_Code],     [_].[Date],     [_].[Amount],     [_].[BU_Key] from (     select [$Outer].[BU_Code],         [$Outer].[Date],         [$Outer].[Amount],         [$Inner].[BU_Key],         [$Inner].[StartDate],         [$Inner].[EndDate]     from [dbo].[fact] as [$Outer]     left outer join     (         select [_].[BU_Key] as [BU_Key],             [_].[BU_Code] as [BU_Code2],             [_].[BU_Name] as [BU_Name],             [_].[StartDate] as [StartDate],             [_].[EndDate] as [EndDate]         from [dbo].[BU] as [_]     ) as [$Inner] on ([$Outer].[BU_Code] = [$Inner].[BU_Code2] or [$Outer].[BU_Code] is null and [$Inner].[BU_Code2] is null) ) as [_] where [_].[Date] >= [_].[StartDate] and [_].[Date] <= [_].[EndDate] The resulting query is a little strange, you can probably tell that it was generated programmatically. But if you look closely you'll notice that every single part of the Power Query formula has been pushed down to SQL Server. Power Query itself ends up just constructing the query and passing the results back to Excel, it does not do any of the data transformation steps itself. So now you can feel a bit more comfortable showing Power Query to your less technical Colleagues knowing that the tool will do it's best fold all the  small steps in Power Query down the most efficient query that it can against the source systems.

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  • I have written an SQL query but I want to optimize it [closed]

    - by ankit gupta
    is there any way to do this using minimum no of joins and select? 2 tables are involved in this operation transaction_pci_details and transaction SELECT t6.transaction_pci_details_id, t6.terminal_id, t6.transaction_no, t6.transaction_id, t6.transaction_type, t6.reversal_flag, t6.transmission_date_time, t6.retrivel_ref_no, t6.card_no,t6.card_type, t6.expires_on, t6.transaction_amount, t6.currency_code, t6.response_code, t6.action_code, t6.message_reason_code, t6.merchant_id, t6.auth_code, t6.actual_trans_amnt, t6.bal_card_amnt, t5.sales_person_id FROM TRANSACTION AS t5 INNER JOIN ( SELECT t4.transaction_pci_details_id, t4.terminal_id, t4.transaction_no, t4.transaction_id, t4.transaction_type, t4.reversal_flag, t4.transmission_date_time, t4.retrivel_ref_no, t4.card_no, t4.card_type, t4.expires_on, t4.transaction_amount, t4.currency_code, t4.response_code, t4.action_code, t3.message_reason_code, t4.merchant_id, t4.auth_code, t4.actual_trans_amnt, t4.bal_card_amnt FROM ( SELECT* FROM transaction_pci_details WHERE message_reason_code LIKE '%OUT%'|| message_reason_code LIKE '%FAILED%' /*we can add date here*/ UNION ALL SELECT t2.transaction_pci_details_id, t2.terminal_id, t2.transaction_no, t2.transaction_id, t2.transaction_type, t2.reversal_flag, t2.transmission_date_time, t2.retrivel_ref_no, t2.card_no, t2.card_type, t2.expires_on, t2.transaction_amount, t2.currency_code, t2.response_code, t2.action_code, t2.message_reason_code, t2.merchant_id, t2.auth_code, t2.actual_trans_amnt, t2.bal_card_amnt FROM ( SELECT transaction_id FROM TRANSACTION WHERE transaction_type_id = 8 ) AS t1 INNER JOIN ( SELECT * FROM transaction_pci_details WHERE message_reason_code LIKE '%appro%' /*we can add date here*/ ) AS t2 ON t1.transaction_id = t2.transaction_id ) AS t3 INNER JOIN ( SELECT* FROM transaction_pci_details WHERE action_code LIKE '%REQ%' /*we can add date here*/ ) AS t4 ON t3.transaction_pci_details_id - t4.transaction_pci_details_id = 1 ) AS t6 ON t5.transaction_id = t6.transaction_id

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