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  • The big last_insert_id() problem, again.

    - by wretrOvian
    Note - this follows my question here: http://stackoverflow.com/questions/2983685/jdbc-does-the-connection-break-if-i-lose-reference-to-the-connection-object Now i have a created a class so i can deal with JDBC easily for the rest of my code - public class Functions { private String DB_SERVER = ""; private String DB_NAME = "test"; private String DB_USERNAME = "root"; private String DB_PASSWORD = "password"; public Connection con; public PreparedStatement ps; public ResultSet rs; public ResultSetMetaData rsmd; public void connect() throws java.io.FileNotFoundException, java.io.IOException, SQLException, Exception { String[] dbParms = Parameters.load(); DB_SERVER = dbParms[0]; DB_NAME = dbParms[1]; DB_USERNAME = dbParms[2]; DB_PASSWORD = dbParms[3]; // Connect. Class.forName("com.mysql.jdbc.Driver").newInstance(); con = DriverManager.getConnection("jdbc:mysql://" + DB_SERVER + "/" + DB_NAME, DB_USERNAME, DB_PASSWORD); } public void disconnect() throws SQLException { // Close. con.close(); } } As seen Parameters.load() refreshes the connection parameters from a file every-time, so that any changes to the same may be applied on the next immediate connection. An example of this class in action - public static void add(String NAME) throws java.io.FileNotFoundException, java.io.IOException, SQLException, Exception { Functions dbf = new Functions(); dbf.connect(); String query = "INSERT INTO " + TABLE_NAME + "(" + "NAME" + ") VALUES(?)"; PreparedStatement ps = dbf.con.prepareStatement(query); ps.setString(1, NAME); ps.executeUpdate(); dbf.disconnect(); } Now here is the problem - for adding a record to the table above, the add() method will open a connection, add the record - and then call disconnect() . What if i want to get the ID of the inserted record after i call add() -like this : Department.add("new dept"); int ID = getlastID(); Isn't it possible that another add() was called between those two statements?

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  • SSRS Performance Mystery

    - by user101654
    I have a stored procedure that returns about 50000 records in 10sec using at most 2 cores in SSMS. The SSRS report using the stored procedure was taking 20min and would max out the processor on an 8 core server for the entire time. The report was relatively simple (i.e. no graphs, calculations). The report did not appear to be the issue as I wrote the 50K rows to a temp table and the report could display the data in a few seconds. I tried many different ideas for testing altering the stored procedure each time, but keeping the original code in a separate window to revert back to. After one Alter of the stored procedure, going back to the original code, the report and server utilization started running fast, comparable to the performance of the stored procedure alone. Everything is fine for now, but I am would like to get to the bottom of what caused this in case it happens again. Any ideas?

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  • SqlCE Flush Interval - Will the default setting lead to corruption?

    - by NormD
    SqlCE has a parameter set on the Connect String called Flush Interval. It is defined as: The interval time (in seconds) before all committed transactions are flushed to disk. If not specified, the default value is 10. I thought that a committed transaction, by definition, is a transaction that has been flushed to disk, specifically the database file. If a transaction is only stored in RAM then cannot the transaction be easily lost? I thought that transactions were first written to a log file and then applied to the database file itself, so perhaps this parameter could mean the time to wait until the transaction log is applied to the database file? I would have thought that this parameter should be 0.

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  • Business object and linq2SQL

    - by Overdose
    What is the optimal way to write the code which interacts with DB using linq2SQL? I need to add some business logic to the entities. So I guess there are two ways: Write some wrapper class. The main minus is that many fields are the same, so i don't feel it as DRY style. Add business logic methods to linq2sql entities(these classes are partial) directly ???

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  • Forcing the use of an index can improve performance?

    - by aF.
    Imagine that we have a query like this: select a.col1, b.col2 from t1 a inner join t2 b on a.col1 = b.col2 where a.col1 = 'abc' Both col1 and col2 don't have any index. If I add another restriction on the where clause, one that is always correct but with a column with an index: select a.col1, b.col2 from t1 a inner join t2 b on a.col1 = b.col2 where a.col1 = 'abc' and a.id >= 0 -- column always true and with index May the query perform faster since it may use the index on id column?

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  • Is a JOIN more/less efficient than EXISTS IN when no data is needed from the second table?

    - by twpc
    I need to look up all households with orders. I don't care about the data of the order at all, just that it exists. Is it more efficient to say something like this: SELECT HouseholdID, LastName, FirstName, Phone FROM Households INNER JOIN Orders ON Orders.HouseholdID = Households.HouseholdID or this: SELECT HouseholdID, LastName, FirstName, Phone FROM Households WHERE EXISTS (SELECT HouseholdID FROM Orders WHERE Orders.HouseholdID = Households.HouseholdID)

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  • MySQL -- How to do this better?

    - by Andrew
    $activeQuery = mysql_query("SELECT count(`status`) AS `active` FROM `assignments` WHERE `user` = $user_id AND `status` = 0"); $active = mysql_fetch_assoc($activeQuery); $failedQuery = mysql_query("SELECT count(`status`) AS `failed` FROM `assignments` WHERE `user` = $user_id AND `status` = 1"); $failed = mysql_fetch_assoc($failedQuery); $completedQuery = mysql_query("SELECT count(`status`) AS `completed` FROM `assignments` WHERE `user` = $user_id AND `status` = 2"); $completed = mysql_fetch_assoc($completedQuery); There has to be a better way to do that, right? I don't know how much I need to elaborate as you can see what I'm trying to do, but is there any way to do all of that in one query? I need to be able to output the active, failed, and completed assignments, preferably in one query.

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  • Difference between "and" and "where" in joins

    - by Midhat
    Whats the difference between SELECT DISTINCT field1 FROM table1 cd JOIN table2 ON cd.Company = table2.Name and table2.Id IN (2728) and SELECT DISTINCT field1 FROM table1 cd JOIN table2 ON cd.Company = table2.Name where table2.Id IN (2728) both return the same result and both have the same explain output

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  • ruby on rails w/ SQLServer

    - by jaydel
    I've heard from some people that RoR doesn't marry cleanly with SQLServer. We have a series of historical, standardization to use SQLServer but if we can push back with valid reasons we can move to another db. One person on the team wants MySql and another wants Postgres, etc. I'm trying to stay out of the religious wars and really understand what the pain point is with SQLServer. We're running the app server on a linux box, and the database will be on a windows box and the SQLServer that we're supposed to standardize on is 2008, if those details help any... thanks in advance!

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  • MySQL, select from different table... IF

    - by gubbfett
    I'm having a small trouble since it was a long time ago i studies databases and querys. For example i'll have two tables for cd:s, one with data and one with alternative translations. In the CD-table i have the original language, and it looks something like this Table for CDs (cds): id | name | language ----------------------- 1 | aaa | en 2 | bbb | en 3 | ccc | fi Table for languages (languages): cd_id | language | name ----------------------- 1 | fi | AAA 1 | de | AAACHTUNG 3 | en | CCC Now, i want to get all these cd:s in for example german, if there's no translation made i want it to be in the original language... How can i do this?

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  • Query to bring count from comma seperated Value

    - by Mugil
    I have Two Tables One for Storing Products and Other for Storing Orders List. CREATE TABLE ProductsList(ProductId INT NOT NULL PRIMARY KEY, ProductName VARCHAR(50)) INSERT INTO ProductsList(ProductId, ProductName) VALUES(1,'Product A'), (2,'Product B'), (3,'Product C'), (4,'Product D'), (5,'Product E'), (6,'Product F'), (7,'Product G'), (8,'Product H'), (9,'Product I'), (10,'Product J'); CREATE TABLE OrderList(OrderId INT NOT NULL PRIMARY KEY AUTO_INCREMENT, EmailId VARCHAR(50), CSVProductIds VARCHAR(50)) SELECT * FROM OrderList INSERT INTO OrderList(EmailId, CSVProductIds) VALUES('[email protected]', '2,4,1,5,7'), ('[email protected]', '5,7,4'), ('[email protected]', '2'), ('[email protected]', '8,9'), ('[email protected]', '4,5,9'), ('[email protected]', '1,2,3'), ('[email protected]', '9,10'), ('[email protected]', '1,5'); Output ItemName NoOfOrders Product A 4 Product B 3 Product C 1 Product D 3 Product E 4 Product F 0 Product G 2 Product H 1 Product I 2 Product J 1 The Order List Stores the ItemsId as Comma separated value for every customer who places order.Like this i am having more than 40k Records in my dB table Now I am assigned with a task of creating report in which I should display Items and No of People ordered Items as Shown Below I Used Query as below in my PHP to bring the Orders One By One and storing in array. SELECT COUNT(PL.EmailId) FROM OrderList PL WHERE CSVProductIds LIKE '2' OR CSVProductIds LIKE '%,2,%' OR CSVProductIds LIKE '%,2' OR CSVProductIds LIKE '2,%'; 1.Is it possible to get the same out put by using Single Query 2.Does using a like in mysql query slows down the dB when the table has more no of records i.e 40k rows

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  • simple query Delete records in a table based on count logic

    - by user1905941
    a table with a pk and status column which is having values as 'Y','N','NULL' Query: get the count of records with status column as 'Y', if this count exceeds 1% of total count of records then dont delete , else delete the records in the table. i tried like this Declare v_count Number; v_count1 Number; BEGIN v_count := select count(*) from temp; v_count1 := select count(*) from temp where status = 'Y' ; v_count := v_count + ((0.1) * (v_count)) if (v_count1 > v_count) { insert into temp1 values(pk,status) } else { Delete from temp ; } END;

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  • Database is very slow when creating an index

    - by kaliyaperumal M
    My database has around 25 core numbers, in that weekly basis I need to create an index and drop index. While creating the index it takes long time to complete, my log file also keeps on increasing, and when I delete some numbers from that table also taking too much time (because weekly basis I have to delete 30 to 50 lack numbers and add 30 to 40 lack new number also). Can u please give me the proper solution..

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  • Left Join only returning one row

    - by Adam
    I am trying to join two tables. I would like all the columns from the product_category table (there are a total of 6 now) and count the number of products, CatCount, that are in each category from the products_has_product_category table. My query result is 1 row with the first category and a total count of 68, when I am looking for 6 rows with each individual category's count. <?php $result = mysql_query(" SELECT a.*, COUNT(b.category_id) AS CatCount FROM `product_category` a LEFT JOIN `products_has_product_category` b ON a.product_category_id = b.category_id "); while($row = mysql_fetch_array($result)) { echo ' <li class="ui-shadow" data-count-theme="d"> <a href="' . $row['product_category_ref_page'] . '.php" data-icon="arrow-r" data-iconpos="right">' . $row['product_category_name'] . '</a><span class="ui-li-count">' . $row['CatCount'] . '</span></li>'; } ?> I have been working on this for a couple of hours and would really appreciate any help on what I am doing wrong.

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  • Count of Sums possibly using group_by

    - by Daniel Johnson
    Say you have a user table and an order table which references user (user has_many orders) and contains an item count field. How could you efficiently ask "how many uses ordered how many items?" That is, to generate something along the lines of: Number of users | sum of items ------------------------------- 5 users | 1 item 4 users | 5 items 1 user | 7 items Thanks in advance.

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  • Is an index required for columns in ON clause?

    - by newbie
    Do I have to create an index on columns referenced in Joins? E.g. SELECT * FROM left_table INNER JOIN right_table ON left_table.foo = right_table.bar WHERE ... Should I create indexes on left_table(foo), right_table(bar), or both? I noticed different results when I used EXPLAIN (Postgresql) with and without indexes and switching around the order of the comparison (right_table.bar = left_table.foo) I know for sure that indexes are used for the left of the WHERE clause but I am wondering whether I need indexes for columns listed in ON clauses.

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  • replicating master tables mapping in transaction tables

    - by NoDisplay
    I have three master tables for location information Country {ID, Name} State {ID, Name, CountryID} City {ID, Name, StateID} Now I have one transcation table called Person which hold the person name and his location information. My Question is shall I have only CityID in the Person table like this: Person {ID, Name, CityID}' And have view of join query which give me detail like "Person{ID,Name,City,State,Country}" or Shall I replicate the mapping Person {ID, Name, CityID, StateID, CountryID} Please suggest which do you feel is to be selected and why? if there is any other option available, please suggest. Thanks in advance.

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  • CodeIgniter - numbers in sql query are masked with ``

    - by Checkson
    Hello, i'm using CodeIgniter for developing a community board. As I'm using nested sets to get a nested forum hierarchy, I have to run a lot of queries such as: SELECT `id` FROM `forums` WHERE 1 BETWEEN `lft` AND `rgt` My problem: CodeIgniter is replacing the "1" by "`1`" because the "1" is recognized as a column name. Of course, the query does not work any more. Is there a way to get it working? thx in advance

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  • Multisite Enabling a Table

    - by Joe Fitzgibbons
    I am creating a table (table A) that will have a number of columns(of course) and there will be another table (table B) that holds metadata associated to rows in table A. I am working with a multi site implementation that has one database for the whole shabang. Rows in table A could belong to any number of sites but must belong to at least one. The problem I have is I am not sure what the best practice is for defining what site each row in table A belongs to. I want performance and scalability. There is no finite number of sites going forward. Rows in table A could belong to any number of sites in the future. Right now there are only 3. My initial thoughts are to have a primary site ID in Table A and then metadata in table B will have rows defining additional sites as needed. Another thought is to have a column in Table A for each site and it is a boolean as to wether it belongs to that site. Lastly I have thought about having another table to map rows in Table A to each site. What is the best way to associate rows in a table with any number of sites with performance and scalability in mind?

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  • Optimizing MySQL queries with IN operator

    - by Arkadiusz Kondas
    I have a MySQL database with a fairly large table where the products are. Each of them has its own id and categoryId field where there is a category id belongs to this product. Now I have a query that pulls out products from given categories such as: SELECT * FROM products WHERE categoryId IN ( 1, 2, 3, 4, 5, 34, 6, 7, 8, 9, 10, 11, 12 ) Of course, come a WHERE clause and ORDER BY sort but not in this thing. Let's say that these products is 250k and the visits are over 100k per day. Under such conditions in the table slow_log registered weight of these queries with large generation time. Do you have any ideas how to optimize the given problem? Table engine is MyISAM.

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  • ms-access: designing a report: printing text on specific x,y coordinates

    - by every_answer_gets_a_point
    i need to design a report that will print text on specified x,y coordinates for example, i will input (50,50), (60,60), (70,70) and i will have my program print text at those specific coordinates on the report. in total there will be about 50 different coordinates. how do i achieve this? should i be using a label control or a textbox? should i be creating the controls dynamically or should i already have controls set at the specified regions?

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