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• How can I make this Java code run faster?

  - by Martin Wiboe

  Hello all, I am trying to make a Java port of a simple feed-forward neural network. This obviously involves lots of numeric calculations, so I am trying to optimize my central loop as much as possible. The results should be correct within the limits of the float data type. My current code looks as follows (error handling & initialization removed): /** * Simple implementation of a feedforward neural network. The network supports * including a bias neuron with a constant output of 1.0 and weighted synapses * to hidden and output layers. * * @author Martin Wiboe */ public class FeedForwardNetwork { private final int outputNeurons; // No of neurons in output layer private final int inputNeurons; // No of neurons in input layer private int largestLayerNeurons; // No of neurons in largest layer private final int numberLayers; // No of layers private final int[] neuronCounts; // Neuron count in each layer, 0 is input // layer. private final float[][][] fWeights; // Weights between neurons. // fWeight[fromLayer][fromNeuron][toNeuron] // is the weight from fromNeuron in // fromLayer to toNeuron in layer // fromLayer+1. private float[][] neuronOutput; // Temporary storage of output from previous layer public float[] compute(float[] input) { // Copy input values to input layer output for (int i = 0; i < inputNeurons; i++) { neuronOutput[0][i] = input[i]; } // Loop through layers for (int layer = 1; layer < numberLayers; layer++) { // Loop over neurons in the layer and determine weighted input sum for (int neuron = 0; neuron < neuronCounts[layer]; neuron++) { // Bias neuron is the last neuron in the previous layer int biasNeuron = neuronCounts[layer - 1]; // Get weighted input from bias neuron - output is always 1.0 float activation = 1.0F * fWeights[layer - 1][biasNeuron][neuron]; // Get weighted inputs from rest of neurons in previous layer for (int inputNeuron = 0; inputNeuron < biasNeuron; inputNeuron++) { activation += neuronOutput[layer-1][inputNeuron] * fWeights[layer - 1][inputNeuron][neuron]; } // Store neuron output for next round of computation neuronOutput[layer][neuron] = sigmoid(activation); } } // Return output from network = output from last layer float[] result = new float[outputNeurons]; for (int i = 0; i < outputNeurons; i++) result[i] = neuronOutput[numberLayers - 1][i]; return result; } private final static float sigmoid(final float input) { return (float) (1.0F / (1.0F + Math.exp(-1.0F * input))); } } I am running the JVM with the -server option, and as of now my code is between 25% and 50% slower than similar C code. What can I do to improve this situation? Thank you, Martin Wiboe

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• Group functions of outer query inside inner query

  - by superdario

  Hello, I'm using Oracle. I'm trying to compose something like this: SELECT trans_type, (SELECT parameter_value FROM transaction_details WHERE id = MAX(t.trans_id)) FROM (SELECT trans_id, trans_type FROM transactions) t GROUP BY trans_type So, I am trying to use a result of grouping inside an inner query. But I am getting the error that I cannot use a group function inside the inner query: ORA-00934: group function is not allowed here Can you offer an alternative other than resorting to another outer query?

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• What is a data structure for quickly finding non-empty intersections of a list of sets?

  - by Andrey Fedorov

  I have a set of N items, which are sets of integers, let's assume it's ordered and call it I[1..N]. Given a candidate set, I need to find the subset of I which have non-empty intersections with the candidate. So, for example, if: I = [{1,2}, {2,3}, {4,5}] I'm looking to define valid_items(items, candidate), such that: valid_items(I, {1}) == {1} valid_items(I, {2}) == {1, 2} valid_items(I, {3,4}) == {2, 3} I'm trying to optimize for one given set I and a variable candidate sets. Currently I am doing this by caching items_containing[n] = {the sets which contain n}. In the above example, that would be: items_containing = [{}, {1}, {1,2}, {2}, {3}, {3}] That is, 0 is contained in no items, 1 is contained in item 1, 2 is contained in itmes 1 and 2, 2 is contained in item 2, 3 is contained in item 2, and 4 and 5 are contained in item 3. That way, I can define valid_items(I, candidate) = union(items_containing[n] for n in candidate). Is there any more efficient data structure (of a reasonable size) for caching the result of this union? The obvious example of space 2^N is not acceptable, but N or N*log(N) would be.

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• How can I check if I made optimal mysql database?

  - by Donator

  Are there any ways to check whether my Mysql database and PHP script are optimal? I want to figure it out and fix if it's possible till I publish it on internet for many users. Thanks.

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• TFS query mixing Tasks and Bugs, sorted by Priority

  - by Val

  We're using TFS with MSF for Agile 4.2 on a project, and I have a bunch of work to do, both Tasks and Bugs. Both are prioritized by our managers, and assigned due dates and target releases. I use a Work Item query as my main TODO list, and I want to list all the Work Items assigned to me, in order by due date and priority. Problem: I can't seem to find a way to write a unified query that will list both Tasks and Bugs sorted by date and then priority. The problem is that Tasks and Bugs use different fields for Priority. So, my query currently lists the tasks by Due Date, then by Task Priority, then it lists Bugs by Due Date, then by Priority. So, I see tasks that are due later than bugs: Title Due Date Priority Task Priority task1 4/23/2010 Medium task2 4/23/2010 High task3 4/30/2010 Low task4 4/30/2010 Medium bug1 4/23/2010 1 bug2 4/23/2010 2 What I want: Title Due Date Priority Task Priority task1 4/23/2010 Medium task2 4/23/2010 High bug1 4/23/2010 1 bug2 4/23/2010 2 task3 4/30/2010 Low task4 4/30/2010 Medium I don't care if the bugs come before or after the tasks on the same due date; I just want all the work items grouped together by due date, so I never see Tasks for a later due date before Bugs for an earlier one. Another problem is the sorting on Task Priority -- alpha sort means I can't get them to sort by the meaning of the priority. But that's a minor problem I can live with if I can get the Tasks and Bugs intermingled. Any way to do this in a single query?

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• MySQL query does not return any data

  - by Alex L

  Hi, I need to retrieve data from a specific time period. The query works fine until I specify the time period. Is there something wrong with the way I specify time period? I know there are many entries within that time-frame. This query returns empty: SELECT stop_times.stop_id, STR_TO_DATE(stop_times.arrival_time, '%H:%i:%s') as stopTime, routes.route_short_name, routes.route_long_name, trips.trip_headsign FROM trips JOIN stop_times ON trips.trip_id = stop_times.trip_id JOIN routes ON routes.route_id = trips.route_id WHERE stop_times.stop_id = 5508 HAVING stopTime BETWEEN DATE_SUB(stopTime,INTERVAL 1 MINUTE) AND DATE_ADD(stopTime,INTERVAL 20 MINUTE); Here is it's EXPLAIN: +----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+ | 1 | SIMPLE | stop_times | ref | trip_id,stop_id | stop_id | 5 | const | 605 | Using where | | 1 | SIMPLE | trips | eq_ref | PRIMARY,route_id | PRIMARY | 4 | wmata_gtfs.stop_times.trip_id | 1 | | | 1 | SIMPLE | routes | eq_ref | PRIMARY | PRIMARY | 4 | wmata_gtfs.trips.route_id | 1 | | +----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+ 3 rows in set (0.00 sec) The query works if I remove the HAVING clause (don't specify time range). Returns: +---------+----------+------------------+-----------------+---------------+ | stop_id | stopTime | route_short_name | route_long_name | trip_headsign | +---------+----------+------------------+-----------------+---------------+ | 5508 | 06:31:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 06:57:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 07:23:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 07:49:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 08:15:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 08:41:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 09:08:00 | "80" | "" | "FORT TOTTEN" | I am using Google Transit format Data loaded into MySQL. The query is supposed to provide stop times and bus routes for a given bus stop. For a bus stop, I am trying to get: Route Name Bus Name Bus Direction (headsign) Stop time The results should be limited only to buses times from 1 min ago to 20 min from now. Please let me know if you could help.

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• How can get unique values from data table using dql?

  - by piemesons

  I am having a table in which there is a column in which various values are stored.i want to retrieve unique values from that table using dql. Doctrine_Query::create() ->select('rec.school') ->from('Records rec') ->where("rec.city='$city' ") ->execute(); Now i want only unique values. Can anybody tell me how to do that... Edit Table Structure: CREATE TABLE IF NOT EXISTS `records` ( `id` int(11) NOT NULL AUTO_INCREMENT, `state` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `city` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `school` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=16334 ; This is the Query I am using: Doctrine_Query::create() ->select('DISTINCT rec.city') ->from('Records rec') ->where("rec.state = '$state'") // ->getSql(); ->execute(); Generting Sql for this gives me: SELECT DISTINCT r.id AS r__id, r.city AS r__city FROM records r WHERE r.state = 'AR' Now check the sql generated:::: DISTINCT is on 'id' column where as i want Distinct on city column. Anybody know how to fix this. EDIT2 Id is unique cause its an auto incremental value.Ya i have some real duplicates in city column like: Delhi and Delhi. Right.. Now when i am trying to fetch data from it, I am getting Delhi two times. How can i make query like this: select DISTINCT rec.city where state="xyz"; Cause this will give me the proper output. EDIT3: Anybody who can tell me how to figure out this query..???

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• Linq query: append column to query results

  - by jrubengb

  I am trying to figure out how to append a column to Linq query results based on the max value of the query. Essentially, I want to create an EnumerableRowCollection of DataRows that would include a max value record with the same value for each record. So if i have a hundred records returned through the query, I want to next calculate the max value of one of the fields, then append that max value to the original query table: DataTable dt = new DataTable(); dt = myDataSet.myDataTable; EnumerableRowCollection<DataRow> qrySelectRecords = (from d in dt.AsEnumerable() where d.Field<DateTime>("readingDate") >= startDate && g.Field<DateTime>("readingDate") <= endDate select d); Here's where I need help: double maxValue = qrySelectRecords.Field<double>("field1").Max(); foreach (DataRow dr in qrySelectRecords) { qrySelectRecords.Column.Append(maxValue) }

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• sql UPDATE, a calculation is used multiple times, can it just be calculated once?

  - by Zachery Delafosse

  UPDATE `play` SET `counter1` = `counter1` + LEAST(`maxchange`, FLOOR(`x` / `y`) ), `counter2` = `counter2` - LEAST(`maxchange`, FLOOR(`x` / `y`) ), `x` = MOD(`x`, `y`) WHERE `x` `y` AND `maxchange` 0 As you can see, " LEAST(`maxchange`, FLOOR(`x` / `y`) ) " is used multiple times, but it should always have the same value. Is there a way to optimize this, to only calculate once? I'm coding this in PHP, for the record.

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• Query returning related assets

  - by GMo

  I have 2 tables, one is an assets table which holds digital assets (e.g. article, images etc), the 2nd table is an asset_links table which maps 1-1 relationships between assets contained within the assets table. Here are the table definitions: Asset +---------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+--------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | source | varchar(255) | YES | | NULL | | | title | varchar(255) | YES | | NULL | | | date_created | datetime | YES | | NULL | | | date_embargo | datetime | YES | | NULL | | | date_expires | datetime | YES | | NULL | | | date_updated | datetime | YES | | NULL | | | keywords | varchar(255) | YES | | NULL | | | status | int(11) | YES | | NULL | | | priority | int(11) | YES | | NULL | | | fk_site | int(11) | YES | MUL | NULL | | | resource_type | varchar(255) | YES | | NULL | | | resource_id | int(11) | YES | | NULL | | | fk_user | int(11) | YES | MUL | NULL | | +---------------+--------------+------+-----+---------+----------------+ Asset_links +-----------+---------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------+---------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | asset_id1 | int(11) | YES | | NULL | | | asset_id2 | int(11) | YES | | NULL | | +-----------+---------+------+-----+---------+----------------+ In the asset_links table there are the following rows: 1 - 3, 1 - 4, 2 - 10, 2 - 56 I am looking to write one query which will return all assets which satisfy any asset search criteria and within the same query return all of the linked asset data for linked assets for that asset. e.g. The query returning assets 1 and 2 would return : Asset 1 attributes - Asset 3 attributes - Asset 4 attributes Asset 2 attributes - Asset 10 attributes - Asset 56 attributes What is the best way to write the query?

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• Sub Query making Query slow.

  - by Muhammad Kashif Nadeem

  Please copy and paste following script. DECLARE @MainTable TABLE(MainTablePkId int) INSERT INTO @MainTable SELECT 1 INSERT INTO @MainTable SELECT 2 DECLARE @SomeTable TABLE(SomeIdPk int, MainTablePkId int, ViewedTime1 datetime) INSERT INTO @SomeTable SELECT 1, 1, DATEADD(dd, -10, getdate()) INSERT INTO @SomeTable SELECT 2, 1, DATEADD(dd, -9, getdate()) INSERT INTO @SomeTable SELECT 3, 2, DATEADD(dd, -6, getdate()) DECLARE @SomeTableDetail TABLE(DetailIdPk int, SomeIdPk int, Viewed INT, ViewedTimeDetail datetime) INSERT INTO @SomeTableDetail SELECT 1, 1, 1, DATEADD(dd, -7, getdate()) INSERT INTO @SomeTableDetail SELECT 2, 2, NULL, DATEADD(dd, -6, getdate()) INSERT INTO @SomeTableDetail SELECT 3, 2, 2, DATEADD(dd, -8, getdate()) INSERT INTO @SomeTableDetail SELECT 4, 3, 1, DATEADD(dd, -6, getdate()) SELECT m.MainTablePkId, (SELECT COUNT(Viewed) FROM @SomeTableDetail), (SELECT TOP 1 s2.ViewedTimeDetail FROM @SomeTableDetail s2 INNER JOIN @SomeTable s1 ON s2.SomeIdPk = s1.SomeIdPk WHERE s1.MainTablePkId = m.MainTablePkId) FROM @MainTable m Above given script is just sample. I have long list of columns in SELECT and around 12+ columns in Sub Query. In my From clause there are around 8 tables. To fetch 2000 records full query take 21 seconds and if I remove Subquiries it just take 4 seconds. I have tried to optimize query using 'Database Engine Tuning Advisor' and on adding new advised indexes and statistics but these changes make query time even bad. Note: As I have mentioned that this is test data to explain my question the real data has lot of tables joins columns but without Sub-Query the results us fine. Any help thanks.

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• Convert Mysql query in Postgresql query

  - by xRobot

  Is there an utility to convert mysql query in postgresql query ?

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• query in query builder in a Table Adapter

  - by Sony

  I am working with the datasets of .net I have an Oracle Query which is working fine . but I copy the query as sql statement within Table Adapter wizard and after I clicked the Query Builder button ,there is SQL syntax error. The query is below: SELECT lead_id, NAME, ADDRESS, CITY, EMAIL, PHONE, PINCODE, STATE, QUALIFICATION, DOB, status FROM (SELECT l.lead_id, l.NAME, l.ADDRESS, l.CITY, l.EMAIL, l.PHONE, l.PINCODE, l.STATE, l.QUALIFICATION, l.DOB, CASE WHEN s.status IS NULL THEN 'Not Updated !' ELSE s.status END status, row_number() over(PARTITION BY l.lead_id ORDER BY t .CREATED_DATE DESC) rn FROM LEADS l JOIN Leads lc ON l.USER_ID = lc.USER_ID AND l.USER_ID = :iuser_id AND(l.CREATED_DATE BETWEEN (TO_DATE(:ifrom_date , 'dd-mm-yyyy') ) AND (TO_DATE (:ito_date, 'dd-mm-yyyy' ) )) LEFT JOIN LEADTRANSACTION t ON l.lead_id = t .lead_id LEFT JOIN STATUS s ON s.STATUS_ID = t .STATUS_ID) WHERE rn = 1;

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• Overhead of calling tiny functions from a tight inner loop? [C++]

  - by John

  Say you see a loop like this one: for(int i=0; i<thing.getParent().getObjectModel().getElements(SOME_TYPE).count(); ++i) { thing.getData().insert( thing.GetData().Count(), thing.getParent().getObjectModel().getElements(SOME_TYPE)[i].getName() ); } if this was Java I'd probably not think twice. But in performance-critical sections of C++, it makes me want to tinker with it... however I don't know if the compiler is smart enough to make it futile. This is a made up example but all it's doing is inserting strings into a container. Please don't assume any of these are STL types, think in general terms about the following: Is having a messy condition in the for loop going to get evaluated each time, or only once? If those get methods are simply returning references to member variables on the objects, will they be inlined away? Would you expect custom [] operators to get optimized at all? In other words is it worth the time (in performance only, not readability) to convert it to something like: ElementContainer &source = thing.getParent().getObjectModel().getElements(SOME_TYPE); int num = source.count(); Store &destination = thing.getData(); for(int i=0;i<num;++i) { destination.insert(thing.GetData().Count(), source[i].getName(); } Remember, this is a tight loop, called millions of times a second. What I wonder is if all this will shave a couple of cycles per loop or something more substantial? Yes I know the quote about "premature optimisation". And I know that profiling is important. But this is a more general question about modern compilers, Visual Studio in particular.

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• SQL Server 2005: Internal Query Processor Error:

  - by Geetha

  I am trying to execute this following procedure in SQL Server 2005. I was able to execute this in my development server and when i tried to use this in the Live Server I am getting an Error "Internal Query Processor Error: The query processor could not produce a query plan. For more information, contact Customer Support Services". am using the same Database and the same format. when we searched in the web it shows some fixes to be used in sql server 2005 to avoid this error but my DBA has confirmed that all the patches are updated in our server. can anyone give me some clue on this. Query: create Procedure [dbo].[sample_Select] @ID as varchar(40) as Declare @Execstring as varchar(1000) set @Execstring = ' Declare @MID as varchar(40) Set @MID = '''+@ID+''' select * from ( select t1.field1, t1.field2 AS field2 , t1.field3 AS field3 , L.field1 AS field1 , L. field2 AS field2 from table1 AS t1 INNER JOIN MasterTable AS L ON L. field1 = t1. field2 where t1. field2 LIKE @MID ) as DataTable PIVOT ( Count(field2) FOR field3 IN (' Select @Execstring=@Execstring+ L.field2 +',' FROM MasterTable AS L inner join table1 AS t1 ON t1.field1= L.field2 Where t1.field2 LIKE @ID set @Execstring = stuff(@Execstring, len(@Execstring), 1, '') set @Execstring =@Execstring +')) as pivotTable' exec (@Execstring)

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• When does n++ execute faster than n=n+1 ?

  - by gcc

  Related: http://stackoverflow.com/questions/24853/c-what-is-the-difference-between-i-and-i In C language, Why does n++ execute faster than n=n+1? (int n=...; n++;) (int n=...; n=n+1;) Our instructor asked that question in today's class. (this is not homework)

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• Why does n++ execute faster than n=n+1 ? [closed]

  - by gcc

  In C language, Why does n++ execute faster than n=n+1? (int n=...; n++;) (int n=...; n=n+1;) Our instructor asked that question in today's class. (this is not homework)

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• How to speed up a query?

  - by Soroush Khosravi

  I have a table that every request to the server, stores on it. For each request I will check that it is banned or not. For example it is a query: select * from requests where request_sessID = '4bc0331d983000902b4718c80f12e9b3' AND request_time > (UNIX_TIMESTAMP() - 3600) AND request_isEnable = 1 I also set the engine from InnoDB to MyISAM and row_format to Dynamic but nothing changed. My Hardware is very strong but it took about a minute to execute ! I am a programmer and newbie to mysql How can Speed Up this query? Thanks in Advance

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• SQL SERVER – Disk Space Monitoring – Detecting Low Disk Space on Server

  - by Pinal Dave

  A very common question I often receive is how to detect if the disk space is running low on SQL Server. There are two different ways to do the same. I personally prefer method 2 as that is very easy to use and I can use it creatively along with database name. Method 1: EXEC MASTER..xp_fixeddrives GO Above query will return us two columns, drive name and MB free. If we want to use this data in our query, we will have to create a temporary table and insert the data from this stored procedure into the temporary table and use it. Method 2: SELECT DISTINCT dovs.logical_volume_name AS LogicalName, dovs.volume_mount_point AS Drive, CONVERT(INT,dovs.available_bytes/1048576.0) AS FreeSpaceInMB FROM sys.master_files mf CROSS APPLY sys.dm_os_volume_stats(mf.database_id, mf.FILE_ID) dovs ORDER BY FreeSpaceInMB ASC GO The above query will give us three columns: drive logical name, drive letter and free space in MB. We can further modify above query to also include database name in the query as well. SELECT DISTINCT DB_NAME(dovs.database_id) DBName, dovs.logical_volume_name AS LogicalName, dovs.volume_mount_point AS Drive, CONVERT(INT,dovs.available_bytes/1048576.0) AS FreeSpaceInMB FROM sys.master_files mf CROSS APPLY sys.dm_os_volume_stats(mf.database_id, mf.FILE_ID) dovs ORDER BY FreeSpaceInMB ASC GO This will give us additional data about which database is placed on which drive. If you see a database name multiple times, it is because your database has multiple files and they are on different drives. You can modify above query one more time to even include the details of actual file location. SELECT DISTINCT DB_NAME(dovs.database_id) DBName, mf.physical_name PhysicalFileLocation, dovs.logical_volume_name AS LogicalName, dovs.volume_mount_point AS Drive, CONVERT(INT,dovs.available_bytes/1048576.0) AS FreeSpaceInMB FROM sys.master_files mf CROSS APPLY sys.dm_os_volume_stats(mf.database_id, mf.FILE_ID) dovs ORDER BY FreeSpaceInMB ASC GO The above query will now additionally include the physical file location as well. As I mentioned earlier, I prefer method 2 as I can creatively use it as per the business need. Let me know which method are you using in your production server. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• SQL SERVER – Weekly Series – Memory Lane – #049

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Two Connections Related Global Variables Explained – @@CONNECTIONS and @@MAX_CONNECTIONS @@CONNECTIONS Returns the number of attempted connections, either successful or unsuccessful since SQL Server was last started. @@MAX_CONNECTIONS Returns the maximum number of simultaneous user connections allowed on an instance of SQL Server. The number returned is not necessarily the number currently configured. Query Editor – Microsoft SQL Server Management Studio This post may be very simple for most of the users of SQL Server 2005. Earlier this year, I have received one question many times – Where is Query Analyzer in SQL Server 2005? I wrote small post about it and pointed many users to that post – SQL SERVER – 2005 Query Analyzer – Microsoft SQL SERVER Management Studio. Recently I have been receiving similar question. OUTPUT Clause Example and Explanation with INSERT, UPDATE, DELETE SQL Server 2005 has a new OUTPUT clause, which is quite useful. OUTPUT clause has access to insert and deleted tables (virtual tables) just like triggers. OUTPUT clause can be used to return values to client clause. OUTPUT clause can be used with INSERT, UPDATE, or DELETE to identify the actual rows affected by these statements. OUTPUT clause can generate a table variable, a permanent table, or temporary table. Even though, @@Identity will still work with SQL Server 2005, however I find the OUTPUT clause very easy and powerful to use. Let us understand the OUTPUT clause using an example. Find Name of The SQL Server Instance Based on database server stored procedures has to run different logic. We came up with two different solutions. 1) When database schema is very much changed, we wrote completely new stored procedure and deprecated older version once it was not needed. 2) When logic depended on Server Name we used global variable @@SERVERNAME. It was very convenient while writing migrating script which depended on the server name for the same database. Explanation of TRY…CATCH and ERROR Handling With RAISEERROR Function One of the developers at my company thought that we can not use the RAISEERROR function in new feature of SQL Server 2005 TRY… CATCH. When asked for an explanation he suggested SQL SERVER – 2005 Explanation of TRY… CATCH and ERROR Handling article as excuse suggesting that I did not give example of RAISEERROR with TRY…CATCH. We all thought it was funny. Just to keep records straight, TRY… CATCH can sure use RAISEERROR function. Different Types of Cache Objects Serveral kinds of objects can be stored in the procedure cache: Compiled Plans: When the query optimizer finishes compiling a query plan, the principal output is compiled plan. Execution contexts: While executing a compiled plan, SQL Server has to keep track of information about the state of execution. Cursors: Cursors track the execution state of server-side cursors, including the cursor’s current location within a resultset. Algebrizer trees: The Algebrizer’s job is to produce an algebrizer tree, which represents the logic structure of a query. Open SSMS From Command Prompt – sqlwb.exe Example This article is written by request and suggestion of Sr. Web Developer at my organization. Due to the nature of this article most of the content is referred from Book On-Line. sqlwbcommand prompt utility which opens SQL Server Management Studio. Squib command does not run queries from the command prompt. sqlcmd utility runs queries from command prompt, read for more information. 2008 Puzzle – Solution – Computed Columns Datatype Explanation Just a day before I wrote article SQL SERVER – Puzzle – Computed Columns Datatype Explanation which was inspired by SQL Server MVP Jacob Sebastian. I suggest that before continuing this article read the original puzzle question SQL SERVER – Puzzle – Computed Columns Datatype Explanation.The question was if the computed column was of datatype TINYINT how to create a Computed Column of datatype INT? 2008 – Find If Index is Being Used in Database It is very often I get a query that how to find if any index is being used in the database or not. If any database has many indexes and not all indexes are used it can adversely affect performance. If the number of indices are higher it reduces the INSERT / UPDATE / DELETE operation but increase the SELECT operation. It is recommended to drop any unused indexes from table to improve the performance. 2009 Interesting Observation – Execution Plan and Results of Aggregate Concatenation Queries If you want to see what’s going on here, I think you need to shift your point of view from an implementation-centric view to an ANSI point of view. ANSI does not guarantee processing the order. Figure 2 is interesting, but it will be potentially misleading if you don’t understand the ANSI rule-set SQL Server operates under in most cases. Implementation thinking can certainly be useful at times when you really need that multi-million row query to finish before the backup fire off, but in this case, it’s counterproductive to understanding what is going on. SQL Server Management Studio and Client Statistics Client Statistics are very important. Many a times, people relate queries execution plan to query cost. This is not a good comparison. Both parameters are different, and they are not always related. It is possible that the query cost of any statement is less, but the amount of the data returned is considerably larger, which is causing any query to run slow. How do we know if any query is retrieving a large amount data or very little data? 2010 I encourage all of you to go through complete series and write your own on the subject. If you write an article and send it to me, I will publish it on this blog with due credit to you. If you write on your own blog, I will update this blog post pointing to your blog post. SQL SERVER – ORDER BY Does Not Work – Limitation of the View 1 SQL SERVER – Adding Column is Expensive by Joining Table Outside View – Limitation of the View 2 SQL SERVER – Index Created on View not Used Often – Limitation of the View 3 SQL SERVER – SELECT * and Adding Column Issue in View – Limitation of the View 4 SQL SERVER – COUNT(*) Not Allowed but COUNT_BIG(*) Allowed – Limitation of the View 5 SQL SERVER – UNION Not Allowed but OR Allowed in Index View – Limitation of the View 6 SQL SERVER – Cross Database Queries Not Allowed in Indexed View – Limitation of the View 7 SQL SERVER – Outer Join Not Allowed in Indexed Views – Limitation of the View 8 SQL SERVER – SELF JOIN Not Allowed in Indexed View – Limitation of the View 9 SQL SERVER – Keywords View Definition Must Not Contain for Indexed View – Limitation of the View 10 SQL SERVER – View Over the View Not Possible with Index View – Limitations of the View 11 SQL SERVER – Get Query Running in Session I was recently looking for syntax where I needed a query running in any particular session. I always remembered the syntax and ha d actually written it down before, but somehow it was not coming to mind quickly this time. I searched online and I ended up on my own article written last year SQL SERVER – Get Last Running Query Based on SPID. I felt that I am getting old because I forgot this really simple syntax. Find Total Number of Transaction on Interval In one of my recent Performance Tuning assignments I was asked how do someone know how many transactions are happening on a server during certain interval. I had a handy script for the same. Following script displays transactions happened on the server at the interval of one minute. You can change the WAITFOR DELAY to any other interval and it should work. 2011 Here are two DMV’s which are newly introduced in SQL Server 2012 and provides vital information about SQL Server. DMV – sys.dm_os_volume_stats – Information about operating system volume DMV – sys.dm_os_windows_info – Information about Operating System SQL Backup and FTP – A Quick and Handy Tool I have used this tool extensively since 2009 at numerous occasion and found it to be very impressive. What separates it from the crowd the most – it is it’s apparent simplicity and speed. When I install SQLBackupAndFTP and configure backups – all in 1 or 2 minutes, my clients are always impressed. Quick Note about JOIN – Common Questions and Simple Answers In this blog post we are going to talk about join and lots of things related to the JOIN. I recently started office hours to answer questions and issues of the community. I receive so many questions that are related to JOIN. I will share a few of the same over here. Most of them are basic, but note that the basics are of great importance. 2012 Importance of User Without Login Question: “In recent version of SQL Server we can create user without login. What is the use of it?” Great question indeed. Let me first attempt to answer this question but after reading my answer I need your help. I want you to help him as well with adding more value to it. Preserve Leading Zero While Coping to Excel from SSMS Earlier I wrote two articles about how to efficiently copy data from SSMS to Excel. Since I wrote that post there are plenty of interest generated on this subject. There are a few questions I keep on getting over this subject. One of the question is how to get the leading zero preserved while copying the data from SSMS to Excel. Well it is almost the same way as my earlier post SQL SERVER – Excel Losing Decimal Values When Value Pasted from SSMS ResultSet. The key here is in EXCEL and not in SQL Server. Solution – 2 T-SQL Puzzles – Display Star and Shortest Code to Display 1 Earlier on this blog we had asked two puzzles. The response from all of you is nothing but Amazing. I have received 350+ responses. Many are valid and many were indeed something I had not thought about it. I strongly suggest you read all the puzzles and their answers here - trust me if you start reading the comments you will not stop till you read every single comment. Seriously trust me on it. Personally I have learned a lot from it. Identify Most Resource Intensive Queries – SQL in Sixty Seconds #028 – Video http://www.youtube.com/watch?v=TvlYy-TGaaA Importance of User Without Login – T-SQL Demo Script Earlier I wrote a blog post about SQL SERVER – Importance of User Without Login and my friend and SQL Expert Vinod Kumar has written excellent follow up blog post about Contained Databases inside SQL Server 2012. Now lots of people asked me if I can also explain the same concept again so here is the small demonstration for it. Let me show you how login without user can help. Before we continue on this subject I strongly recommend that you read my earlier blog post here. In following demo I am going to demonstrate following situation. Login using the System Admin account Create a user without login Checking Access Impersonate the user without login Checking Access Revert Impersonation Give Permission to user without login Impersonate the user without login Checking Access Revert Impersonation Clean up Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL server query not showing daily date result

  - by Andrew Jahn

  I have a simple user production report where daily quotas are tracked. The sql returns a weeks worth of data for all users and for each day it tracks their totals. The problem is if they are out for a day and have a zero production for that day then the result query just skips that day and leaves it out. I want to return days even if the table has no entries for the person on that day. table: user date andy 3/22/10 andy 3/22/10 andy 3/23/10 andy 3/24/10 andy 3/26/10 result: andy 3/22/10 2 3/23/10 1 3/24/10 1 3/25/10 0 3/26/10 1 So my question is how do I get the query to return that 3/25/10 date with a count of 0. (current query I'm using): SELECT A.USUS_ID as Processor, CONVERT(VARCHAR(10),A.CLST_STS_DTM,101) as Date, COUNT(A.CLCL_ID) as DailyTotal FROM CMC_CLST_STATUS A WHERE A.CLST_STS_DTM >= (@Day) AND DATEADD(d, 5, @Day) > A.CLST_STS_DTM GROUP BY A.USUS_ID, CONVERT(VARCHAR(10),A.CLST_STS_DTM,101) ORDER BY A.USUS_ID, CONVERT(VARCHAR(10),A.CLST_STS_DTM,101)

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• SQL query to show what has been paid each month

  - by Tommy Jakobsen

  I'm looking for help to create a query, to solve the following problem: Let's imagine the row: Name StartDate EndDate Payed James 10-10-2010 17-02-2011 860 And heres the schema for the table as requested: payment_details (name VARCHAR(50) NOT NULL, start_date DATETIME NOT NULL, end_date DATETIME NOT NULL, payed FLOAT NOT NULL) Now I need a way to split this row up, so I can see what he pays every month, for his period, a query that returns: Name Year Month Payed James 2010 10 172 James 2010 11 172 James 2010 12 172 James 2011 01 172 James 2011 02 172 There are lots of different customers with different StartDate/EndDate and amount payed, so the query has to handle this aswell. How can I do this in SQL (MS SQL Server 2005)? Help will be much appreciated!

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• SQL query to show what has been payed each

  - by Tommy Jakobsen

  I'm looking for help to create a query, to solve the following problem: Let's imagine the row: Name StartDate EndDate Payed James 10-10-2010 17-02-2011 860 Now I need a way to split this row up, so I can see what he pays every month, for his period, a query that returns: Name Year Month Payed James 2010 10 172 James 2010 11 172 James 2010 12 172 James 2011 01 172 James 2010 02 172 There are lots of different customers with different StartDate/EndDate and amount payed, so the query has to handle this aswell. How can I do this in SQL (MS SQL Server 2005)? Help will be much appreciated!

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• Query for props list with or without values

  - by vitto

  Hi, I'm trying to make a SELECT on three relational tables like these ones: table_materials -> material_id - material_name table_props -> prop_id - prop_name table_materials_props - row_id -> material_id -> prop_id - prop_value On my page, I'd like to get a result like this one but i have some problem with the query: material prop A prop B prop C prop D prop E wood 350 NULL NULL 84 16 iron NULL 17 NULL NULL 201 copper 548 285 99 NULL NULL so the query should return something like: material prop_name prop_value wood prop A 350 wood prop B NULL wood prop C NULL wood prop D 84 wood prop E 16 // and go on with others rows i thought to use something like: SELECT * FROM table_materials AS m INNER JOIN table_materials_props AS mp ON m.material_id = mp.material_id INNER JOIN table_materials_props AS p ON mp.prop_id = p.prop_id ORDER BY p.prop_name the problem is the query doesn't return the NULL values, and I need the same prop order for all the materials regardless of prop values are NULL or not I hope this example is clear!

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• NOT IN statement for Visual Studio's Query Builder for TableAdapter

  - by Fabiano

  Hi I want to realize a query with the Visual Studio 2008 build in Query Builder for a TableAdapter similar like following (MSSQL 2008): select * from [MyDB].[dbo].[MyView] where UNIQUE_ID NOT IN ('MyUniqueID1','MyUniqueID2') How do I have to set the Filter in my query in order to call it with the myTableAdapter.GetDataExceptUniqueIds(...) function? I tried to set the filter to NOT IN (@ids) and called it with string[] uniqueIds = ...; myTableAdapter.GetDataExceptUniqueIds(String.Join("','", uniqueIds)); and with StringBuilder sb = new StringBuilder("'"); sb.Append(String.Join("','", uniqueIds)); sb.Append("'"); return myTableAdapter.GetDataExceptUniqueIds(sb.ToString()); but both failed

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