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  • Make All Types Constant by Default in C++

    - by Jon Purdy
    What is the simplest and least obtrusive way to indicate to the compiler, whether by means of compiler options, #defines, typedefs, or templates, that every time I say T, I really mean T const? I would prefer not to make use of an external preprocessor. Since I don't use the mutable keyword, that would be acceptable to repurpose to indicate mutable state. Potential (suboptimal) solutions so far: // I presume redefinition of keywords is implementation-defined or illegal. #define int int const #define ptr * const int i(0); int ptr j(&i); typedef int const Int; typedef int const* const Intp; Int i(0); Intp j(&i); template<class T> struct C { typedef T const type; typedef T const* const ptr; }; C<int>::type i(0); C<int>::ptr j(&i);

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  • How to query by recent date and value in SQL?

    - by wsb3383
    I have a table with three columns: patient_id, obs_date, and weight_val. patient_id stores patient identification #, weight_val stores a weight value, and obs_date stores the date when the weight reading was taken. So, a patient can have many different weight readings at different dates. How do you write a query for: select all patients whose last weight reading is 120?

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  • c++ problem, maybe with types...

    - by Infinity
    Hi guys! I have a little problem in my code. The variables don't want to change their values. Can you say why? Here is my code: vector<coordinate> rocks(N); double angle; double x, y; // other code while (x > 1.0 || x < -1.0 || y > 1.0 || y < -1.0) { angle = rand() * 2.0 * M_PI; cout << angle << endl; cout << rocks[i - 1].x << endl; cout << rocks[i - 1].y << endl; x = rocks[i-1].x + r0 * cos(angle); y = rocks[i-1].y + r0 * sin(angle); cout << x << endl; cout << y << endl << endl; } // other code And the result on the console is: 6.65627e+09 0.99347 0.984713 1.09347 0.984713 1.16964e+09 0.99347 0.984713 1.09347 0.984713 As you see the values of x, y variables doesn't change and this while be an infinity loop. What's the problem? What do you think?

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  • SQL grouping query question; evaluating a group of rows based on the value of one field.

    - by user324575
    I've got table vendorparts that lists all my parts and their vendor(s). Parts with multiple vendors have multiple records in this table. I'm trying to write a query that only returns the partid, and vendor of parts that do not have a default vendor assigned. Partid Vendor Defaultflag 1 A 1 2 B 0 2 C 0 3 D 0 3 E 0 3 F 1 4 G 0 I would like to return the following: Partid Vendor 2 A 2 B 4 G I'm obviously having issues with partid 3 and getting the query to see it as having a default vendor assigned.

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  • sql: how to use count for a particular column ,(or) to count a particular column by its field name

    - by Aravintha Bashyam
    in my query i need a to count a particular column by its field name, SELECT C.INC_COUNT, MIN_X, MIN_Y, MAX_X, MAX_Y, B.STATE_ABBR, B.STATE_NAME, B.LATITUDE, B.LONGITUDE, A.STATE, GEO_ID, concat(A.LSAD_TRANS,' ' , A.NAME) DIST_NAME, A.LSAD, GeometryType(SHAPE) GEO_TYPE, AsText(SHAPE) GEOM from SHAPE_LAYERS A join SHAPE_LAYER_STATE_DESC B on ( A.state = B.state) left outer join INC_DIST_SUMMARY_ALL C on (C.SHAPE_GEO_ID = A. GEO_ID) here i have to count by B.STATE_NAME ,C.INC_COUNT if exmple the field name nevada means i have to get all neveda value count and the C.INC_COUNT.

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  • How many SQL queries per HTTP request is optimal?

    - by Chris Kooken
    I know the answer to this question for the most part is "It Depends", however I wanted to see if anyone had some pointers. We execute queries each request in ASP.NET MVC. Each request we need to get user rights information, and Various data for the Views that we are displaying. How many is too much, I know I should be conscious to the number of queries i am executing. I would assume if they are small queries and optimized out, half-a-dozen should be okay? Am I right? What do you think?

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  • SQL Server - how to determine if indexes aren't being used?

    - by rwmnau
    I have a high-demand transactional database that I think is over-indexed. Originally, it didn't have any indexes at all, so adding some for common processes made a huge difference. However, over time, we've created indexes to speed up individual queries, and some of the most popular tables have 10-15 different indexes on them, and in some cases, the indexes are only slightly different from each other, or are the same columns in a different order. Is there a straightforward way to watch database activity and tell if any indexes are not hit anymore, or what their usage percentage is? I'm concerned that indexes were created to speed up either a single daily/weekly query, or even a query that's not being run anymore, but the index still has to be kept up to date every time the data changes. In the case of the high-traffic tables, that's a dozen times/second, and I want to eliminate indexes that are weighing down data updates while providing only marginal improvement.

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  • Why would SQL be very slow when doing updates?

    - by ooo
    Suddenly doing updates into a few tables have gotten 10 times slower than they used to be. What are some good recommendations to determine root cause and optimization? Could it be that indexing certain columns are causing updates to be slow? Any other recommendations? I guess more important than guesses would be help on the process of identifying the root cause or metrics around performance. Is there anything in Fluent NHibernate that you can use to help identify the root cause of performance issues?

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  • Design classes/interface to support methods returning different types

    - by Nayn
    Hi, I have classes as below. public interface ITest <T> { public T MethodHere(); } public class test1 implements ITest<String> { String MethodHere(){ return "Bla"; } } public class test2 implements ITest<Integer> { Integer MethodHere(){ return Integer.valueOf(2); } } public class ITestFactory { public static ITest getInstance(int type) { if(type == 1) return new test1(); else if(type == 2) return new test2(); } } There is a warning in the factory class that ITest is used as raw type. What modification should I do to get rid of it? Thanks Nayn

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  • which sql query is more efficient: select count(*) or select ... where key>value?

    - by davka
    I need to periodically update a local cache with new additions to some DB table. The table rows contain an auto-increment sequential number (SN) field. The cache keeps this number too, so basically I just need to fetch all rows with SN larger than the highest I already have. SELECT * FROM table where SN > <max_cached_SN> However, the majority of the attempts will bring no data (I just need to make sure that I have an absolutely up-to-date local copy). So I wander if this will be more efficient: count = SELECT count(*) from table; if (count > <cache_size>) // fetch new rows as above I suppose that selecting by an indexed numeric field is quite efficient, so I wander whether using count has benefit. On the other hand, this test/update will be done quite frequently and by many clients, so there is a motivation to optimize it.

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  • How do I remove database name from SQL Server generated script?

    - by bucha
    Anytime I use 'script table as' - 'Insert To' (or other command), the script generated automatically places the database name in the script. Such as: INSERT INTO [DatabaseName].[dbo].[tblToBeInserted] ... While not a huge problem to just delete it, it has slipped by a few times and the script breaks if run on a different server with a different database name but has the same schema. (Such as running on [DatabaseName.Test]) Is there an option I can change, or can I modify the output in any way to remove this?

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  • Nested/Sub data types in haskell

    - by Tom Carstens
    So what would be nice is if you could do something like the following (not necessarily with this format, just the general idea): data Minor = MinorA | MinorB data Major = Minor | MajorB isMinor :: Major -> Bool isMinor Minor = True isMinor _ = False So isMinor MinorA would report True (instead of an error.) At the moment you might do something like: data Major = MinorA | MinorB | MajorB isMinor :: Major -> Bool isMinor MinorA = True isMinor MinorB = True isMinor _ = False It's not terrible or anything, but it doesn't expand nicely (as in if Minor when up to MinorZ this would be terribly clunky). To avoid that problem you can wrap Minor: data Minor = MinorA | MinorB data Major = MajorA Minor | MajorB isMinor :: Major -> Bool isMinor (MajorA _) = True isMinor _ = False But now you have to make sure to wrap your Minors to use them as a Major... again not terrible; just doesn't really express the semantics I'd like very well (i.e. Major can be any Minor or MajorB). The first (legal) example is "Major can be MinorA..." but doesn't have any knowledge of Minor and the second is "Major can be MajorA that takes a Minor..." p.s. No, this isn't really about anything concrete.

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  • SQL Reporting Services 2005 - Date field based on a user entered date?

    - by Pierce
    Hi, I have a report in report services 2005 that has two date fields. The problem is that if users run this for a large section of time it uses too much resources on our server. It is possible to only allow the end user to enter the start date and then the end date be auto populated/derived from this field (for example they enter the 1st of a month and this automatically change the end date to the last of a month.)

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