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  • get n records at a time from a temporary table

    - by Claudiu
    I have a temporary table with about 1 million entries. The temporary table stores the result of a larger query. I want to process these records 1000 at a time, for example. What's the best way to set up queries such that I get the first 1000 rows, then the next 1000, etc.? They are not inherently ordered, but the temporary table just has one column with an ID, so I can order it if necessary. I was thinking of creating an extra column with the temporary table to number all the rows, something like: CREATE TEMP TABLE tmptmp AS SELECT ##autonumber somehow##, id FROM .... --complicated query then I can do: SELECT * FROM tmptmp WHERE autonumber>=0 AND autonumber < 1000 etc... how would I actually accomplish this? Or is there a better way? I'm using Python and PostgreSQL.

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  • How do I do a table join on two fields in my second table?

    - by Cannonade
    I have two tables: Messages - Amongst other things, has a to_id and a from_id field. People - Has a corresponding person_id I am trying to figure out how to do the following in a single linq query: Give me all messages that have been sent to and from person x (idself). I had a couple of cracks at this. Not quite right MsgPeople = (from p in db.people join m in db.messages on p.person_id equals m.from_id where (m.from_id == idself || m.to_id == idself) orderby p.name descending select p).Distinct(); This almost works, except I think it misses one case: "people who have never received a message, just sent one to me" How this works in my head So what I really need is something like: join m in db.messages on (p.people_id equals m.from_id or p.people_id equals m.to_id) Gets me a subset of the people I am after It seems you can't do that. I have tried a few other options, like doing two joins: MsgPeople = (from p in db.people join m in AllMessages on p.person_id equals m.from_id join m2 in AllMessages on p.person_id equals m2.to_id where (m2.from_id == idself || m.to_id == idself) orderby p.name descending select p).Distinct(); but this gives me a subset of the results I need, I guess something to do with the order the joins are resolved. My understanding of LINQ (and perhaps even database theory) is embarrassingly superficial and I look forward to having some light shed on my problem.

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  • MySQL Limiting a query to one consistent value

    - by Lucas Matos
    My current query returns a table like: +------------+ value1 | .... value1 | .... value2 | .... value3 | .... +------------+ I want: +------------+ value1 | .... value1 | .... +------------+ I want to only receive all rows with the first value. Normally I would do a WHERE clause if I knew that value, and I cannot use a LIMIT because each value has a different number of rows. Right now My query looks like "SELECT u.*, n.something, w.* FROM ... AS u, ... AS n, ... AS w WHERE u.id = n.id AND w.val = n.val AND u.desc LIKE '%GET REQUEST VARIABLE%';" This works great, except I get way too many rows and using PHP to do this ruins code portability and is superfluous. Thanks for reading

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  • ora-30926 error

    - by user1331181
    I am trying to execute the following merge statement but is is showing me ora-30926 error merge into test_output target_table USING (SELECT c.test_code, c.v_report_id, upper_score, CASE WHEN c.test_code = 1 THEN b.mean_diff WHEN c.test_code = 2 THEN b.norm_dist WHEN c.test_code = 3 THEN b.ks_stats WHEN c.test_code = 4 THEN b.ginni WHEN c.test_code = 5 THEN b.auroc WHEN c.test_code = 6 THEN b.info_stats WHEN c.test_code = 7 THEN b.kl_stats END val1 FROM combined_approach b inner join test_output c on b.v_report_id = c.v_report_id and c.upper_score = b.band_code WHERE c.v_report_id = lv_report_id ORDER BY c.test_code) source_table on(target_table.v_report_id = source_table.v_report_id and target_table.v_report_id = lv_report_id) when matched then update SET target_table.upper_value = source_table.val1;

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  • “Function” calling inside store procedure

    - by idimba
    Hi, I have a big store procedure, that contains a lot of INSERTs. There're many INSERTS that almost identical - they're different by some parameter(s) (all INSERTs to the same table) Is there a way to create a function/method, to which I'll pass the above parameter(s) and the function/method will generate concrete INSERT's? Thanks

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  • help with delete where not in query

    - by kralco626
    I have a lookup table (##lookup). I know it's bad design because I'm duplicating data, but it speeds up my queries tremendously. I have a query that populates this table insert into ##lookup select distinct col1,col2,... from table1...join...etc... I would like to simulate this behavior: delete from ##lookup insert into ##lookup select distinct col1,col2,... from table1...join...etc... This would clearly update the table correctly. But this is a lot of inserting and deleting. It messes with my indexes and locks up the table for selecting from. This table could also be updated by something like: delete from ##lookup where not in (select distinct col1,col2,... from table1...join...etc...) insert into ##lookup (select distinct col1,col2,... from table1...join...etc...) except if it is already in the table The second way may take longer, but I can say "with no lock" and I will be able to select from the table. Any ideas on how to write the query the second way?

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  • Using SQL Server Views with NHibernate

    - by colinramsay
    I have a site that sells cars. On the frontend, I want to only show cars that are published, and on the backend I want to show all cars. Whether a car is published or not depends on a number of factors, so I wanted to create a view to simplify this. My question is, can I reduce duplication by dynamically telling NHibernate to sometimes use the "PublishedCar" view and something use the "AllCar" view when querying/fetching Car entities?

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  • Is there a better way to do updates in LinqToSQL?

    - by Vaccano
    I have a list (that comes to my middleware app from the client) that I need to put in my database. Some items in the list may already be in the db (just need an update). Others are new inserts. This turns out to be much harder than I thought I would be. Here is my code to do that. I am hoping there is a better way: public void InsertClients(List<Client> clients) { var comparer = new LambdaComparer<Client>((x, y) => x.Id == y.Id); // Get a listing of all the ones we will be updating var alreadyInDB = ctx.Clients .Where(client => clients.Contains(client, comparer)); // Update the changes for those already in the db foreach (Client clientDB in alreadyInDB) { var clientDBClosure = clientDB; Client clientParam = clients.Find(x => x.Id == clientDBClosure.Id); clientDB.ArrivalTime = clientParam.ArrivalTime; clientDB.ClientId = clientParam.ClientId; clientDB.ClientName = clientParam.ClientName; clientDB.ClientEventTime = clientParam.ClientEventTime; clientDB.EmployeeCount = clientParam.EmployeeCount; clientDB.ManagerId = clientParam.ManagerId; } // Get a list of all clients that are not in my the database. var notInDB = clients.Where(x => alreadyInDB.Contains(x, comparer) == false); ctx.Clients.InsertAllOnSubmit(notInDB); ctx.SubmitChanges(); } This seems like a lot of work to do a simple update. But maybe I am just spoiled. Anyway, if there is a easier way to do this please let me know. Note: If you are curious the code to the LambdaComparer is here: http://gist.github.com/335780#file_lambda_comparer.cs

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  • Changing newid() to newsequentialid() on an existing table

    - by cbp
    Hi, At the moment we have a number of tables that are using newid() on the primary key. This is causing large amounts of fragmentation. So I would like to change the column to use newsequentialid() instead. I imagine that the existing data will remain quite fragmented but the new data will be less fragmented. This would imply that I should perhaps wait some time before changing the PK index from non-clustered to clustered. My question is, does anyone have experience doing this? Is there anything I have overlooked that I should be careful of?

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  • WHERE condition accross multiple rows

    - by Chris G
    I have this table... -------------------------------------- | user_id | status | status_date | -------------------------------------- | 1 | Current | 2012-08-01 | | 1 | Referral | 2012-03-14 | | 2 | Referral | 2012-04-23 | | | | | -------------------------------------- How would I query to find a distinct user_id who has a referral date before 2012-06-30 AND either a current date of after 2012-06-30 or no current status record at all? Database is MySQL.

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  • LINQ TO SQL, Dynamic query with DATE type fields

    - by acanthus
    Hello, I'm building a query with the LINQ dynamic library so I don't know how many potential parameters will I have and I get an error when trying to query DATE type fields: Operator '=' incompatible with operand types 'DateTime' and 'String' When I step through the debugger in the Dynamic.cs it shows that the value is of type string and the field is of type date so the problem is obvious but I have no idea how to approach it. Any ideas? BR

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  • Determining child count of path

    - by sqlnewbie
    I have a table whose 'path' column has values and I would like to update the table's 'child_count' column so that I get the following output. path | child_count --------+------------- | 5 /a | 3 /a/a | 0 /a/b | 1 /a/b/c | 0 /b | 0 My present solution - which is way too inefficient - uses a stored procedure as follows: CREATE FUNCTION child_count() RETURNS VOID AS $$ DECLARE parent VARCHAR; BEGIN FOR parent IN SELECT path FROM my_table LOOP DECLARE tokens VARCHAR[] := REGEXP_SPLIT_TO_ARRAY(parent, '/'); str VARCHAR := ''; BEGIN FOR i IN 2..ARRAY_LENGTH(tokens, 1) LOOP UPDATE my_table SET child_count = child_count + 1 WHERE path = str; str := str || '/' || tokens[i]; END LOOP; END; END LOOP; END; $$ LANGUAGE plpgsql; Anyone knows of a single UPDATE statement that does the same thing?

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  • How do I put data from multiple records into different columns?

    - by Bryan
    My two tables are titled analyzed and analyzedCopy3. I'm trying to put information from analyzedCopy3 into multiple columns in analyzed. Sample data from analyzedCopy3: readings_miu_id OriginalCol ColRSSIz 110001366 Frederick Road -108 110001366 Steel Street 110001366 Fifth Ave. 110001508 Steel Street -104 What I want to do is put the top 3 OriginalCol, ColRSSIz combinations into columns that I have in the table analyzed. In analyzed there is only one record for each unique readings_miu_id. Any ideas? Thanks in advance. Additional Info: By "top 3 OriginalCol, ColRSSIz combinations" I mean the first 3 combinations with the highest value in the ColRSSIz column. For any readings_miu_id there could be anywhere from 1 row of information to 6 rows of information. So at most I'm only wanting the top 3. If there is less than 3 rows for the readings_miu_id then the other columns need to be blank. Query that generates the table "analyzed": strSql4 = " SELECT readings_miu_id, Count(readings_miu_id) as NumberOfReads, First(PercentSuccessz) as PercentSuccess, First(Readingz)as Reading, First(MIUwindowz) as MIUwindow, First(SNz) as SN, First(Noisez) as Noise, First(RSSIz) as RSSI, First(ColRSSIz) as ColRSSI, First(MIURSSIz) as MIURSSI, First(Col1z) as Col1, First(Col1RSSIz) as Col1RSSI, First(Col2z) as Col2, First(Col2RSSIz) as Col2RSSI, First(Col3z) as Col3, First(Col3RSSIz) as Col3RSSI, First(Firmwarez) as Firmware, First(CFGDatez) as CFGDate, First(FreqCorrz) as FreqCorr, First(Activez) as Active, First(MeterTypez) as MeterType, First(OriginColz) as OriginCol, First(ColIDz) as ColID, First(Ownagez) as Ownage, First(SiteIDz) as SiteID, First(PremIDz) as PremID, First(prem_group1z) as prem_group1, First(prem_group2z) as prem_group2, First(ReadIDz) as ReadID, First(prem_addr1z) as prem_addr1 " & _ "INTO analyzed " & _ "FROM analyzedCopy2 " & _ "GROUP BY readings_miu_id, PremIDz; " DoCmd.SetWarnings False DoCmd.RunSQL strSql4 DoCmd.SetWarnings True

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  • Database design -- does it respect 3rd NF?

    - by Flavius
    Hi I have the following relations (tables) in a relational model Person person_id, first_name, last_name, address Student person_id, matr_nr Teacher person_id, salary Lecture lecture_id, lect_name, lect_description Attendees lecture_id, person_id, date I'm wondering about the functional dependencies of Student and Teacher. Do these tables respect the 3rd normal form? Which should be the primary keys of these tables?

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  • What is the most "database independent" way of creating a variable length text field in a database

    - by Thibaut Colar
    I want to create a text field in the database, with no specific size (it will store text of length unknown in some case) - the particular text are serialized simple object (~ JSON) What is the most database independent way to do this : - a varchar with no size specified (don't think all db support this) - a 'text' field, this seems to be common, but I don't believe it's a standard - a blob or other object of that kind ? - a varchar of a a very large size (that's inefficient and wastes disk space probably) - Other ? I'm using JDBC, but I'd like to use something that is supported in most DB (oracle, mysql, postgresql, derby, HSQL, H2 etc...) Thanks.

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  • Oracle: how to UPSERT (update or insert into a table?)

    - by Mark Harrison
    The UPSERT operation either updates or inserts a row in a table, depending if the table already has a row that matches the data: if table t has a row exists that has key X: update t set mystuff... where mykey=X else insert into t mystuff... Since Oracle doesn't have a specific UPSERT statement, what's the best way to do this?

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  • Help Me With This MS-Access Query

    - by yae
    I have 2 tables: "products" and "pieces" PRODUCTS idProd product price PIECES id idProdMain idProdChild quant idProdMain and idProdChild are related with the table: "products". Other considerations is that 1 product can have some pieces and 1 product can be a piece. Price product equal a sum of quantity * price of all their pieces. "Products" table contains all products (p EXAMPLE: TABLE PRODUCTS (idProd - product - price) 1 - Computer - 300€ 2 - Hard Disk - 100€ 3 - Memory - 50€ 4 - Main Board - 100€ 5 - Software - 50€ 6 - CDroms 100 un. - 30€ TABLE PIECES (id - idProdMain - idProdChild - Quant.) 1 - 1 - 2 - 1 2 - 1 - 3 - 2 3 - 1 - 4 - 1 WHAT I NEED? I need update the price of the main product when the price of the product child (piece) is changed. Following the previous example, if I change the price of this product "memory" (is a piece too) to 60€, then product "Computer" will must change his price to 320€ How I can do it using queries? Already I have tried this to obtain the price of the main product, but not runs. This query not returns any value: SELECT Sum(products.price*pieces.quant) AS Expr1 FROM products LEFT JOIN pieces ON (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdMain) WHERE (((pieces.idProdMain)=5)); MORE INFO The table "products" contains all the products to sell that it is in the shop. The table "pieces" is to take a control of the compound products. To know those who are the products children. For example of compound product: computers. This product is composed by other products (motherboard, hard disk, memory, cpu, etc.)

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  • Replace always replacing null values

    - by Mike
    Why does left(FIELD, replace(nullif(charindex('-', FIELD), 0), null, len(FIELD))) always return null? The idea behind the query is that if charindex() returns 0, then convert the results into null, then convert the null into the length of the field. So if '-' does not exist, show the whole string. For some reason it makes every row equal null. Thank you.

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  • How to get only one record for each duplicate rows of the id in oracle?

    - by Psychocryo
    suppose i have this table: group_id | image | image_id | ----------------------------- 23 blob 1 23 blob 2 23 blob 3 21 blob 4 21 blob 5 25 blob 6 25 blob 7 how to get results of only 1 of each group id? in this case,there may be multiple images for one group id, i just want one result of each group_id i tried distinct but i will only get group_id. max for image also would not work.

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  • Can I lock rows in a cursor if the cursor only returns a single count(*) row?

    - by RenderIn
    I would like to restrict users from inserting more than 3 records with color = 'Red' in my FOO table. My intentions are to A) retrieve the current count so that I can determine whether another record is allowed and B) prevent any other processes from inserting any Red records while this one is in process, hence the for update of. I'd like to do something like: cursor cur_cnt is select count(*) cnt from foo where foo.color = 'Red' for update of foo.id; Will this satisfy both my requirements or will it not lock only the rows in the count(*) who had foo.color = 'Red'?

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  • How to output multiple rows from an SQL query using the mysqli object

    - by Jonathan
    Assuming that the mysqli object is already instantiatied (and connected) with the global variable $mysql, here is the code I am trying to work with. class Listing { private $mysql; function getListingInfo($l_id = "", $category = "", $subcategory = "", $username = "", $status = "active") { $condition = "`status` = '$status'"; if (!empty($l_id)) $condition .= "AND `L_ID` = '$l_id'"; if (!empty($category)) $condition .= "AND `category` = '$category'"; if (!empty($subcategory)) $condition .= "AND `subcategory` = '$subcategory'"; if (!empty($username)) $condition .= "AND `username` = '$username'"; $result = $this->mysql->query("SELECT * FROM listing WHERE $condition") or die('Error fetching values'); $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; return $info; } } there are several hundred listings in the db and when I call $result-fetch_array() it places in an array the first row in the db. however when I try to call the object, I can't seem to access more than the first row. for instance: $listing_row = new Listing; while ($listing = $listing_row-getListingInfo()) { echo $listing[0]; } this outputs an infinite loop of the same row in the db. Why does it not advance to the next row? if I move the code: $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; if I move this outside the class, it works exactly as expected outputting a row at a time while looping through the while statement. Is there a way to write this so that I can keep the fetch_array() call in the class and still loop through the records?

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