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  • Creating Two Cascading Foreign Keys Against Same Target Table/Col

    - by alram
    I have the following tables: user (userid int [pk], name varchar(50)) action (actionid int [pk], description nvarchar(50)) being referenced by another table that captures the relationship: <user1> <action>'s <user2>. I did this with the following table: userAction (userActionId int [pk], actionid int [fk: action.actionid], **userId1 int [fk ref's user.userid; on del/update cascade], userId2 int [fk ref's user.userid; on del/update cascade]**). However, when I try to save the userAction table i get an error because I have two cascading fk's against user.userid. Is there any way to remedy this or must I use a trigger?

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  • What is the best design for these data base tables?

    - by Mohammed Jamal
    I need to find the best solution to make the DB Normalized with large amount of data expected. My site has a Table Tags (contain key word,id) and also 4 types of data related to this tags table like(articles,resources,jobs,...). The big question is:- for the relation with tags what best solution for optimazaion & query speed? make a table for each relation like: table articlesToTags(ArticleID,TagID) table jobsToTags(jobid,tagid) etc. or put it all in one table like table tagsrelation(tagid,itemid,itemtype) I need your help. Please provide me with articles to help me in this design consider that in future the site can conation new section relate to tag Thanks

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  • How can I check a type's dependents order to drop them and replace/modify the initial type?

    - by pctroll
    I tried to modify a type using the following code and it gave me the error code: 'ORA-02303'. I don't know much about Oracle or PL/SQL but I need to solve this; so I'd appreciate any further help with this. Thanks in advance. The code is just an example. But then again, I need to check its dependents first. create or replace type A as object ( x_ number, y_ varchar2(10), member procedure to_upper ); /

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  • Two radically different queries against 4 mil records execute in the same time - one uses brute force.

    - by IanC
    I'm using SQL Server 2008. I have a table with over 3 million records, which is related to another table with a million records. I have spent a few days experimenting with different ways of querying these tables. I have it down to two radically different queries, both of which take 6s to execute on my laptop. The first query uses a brute force method of evaluating possibly likely matches, and removes incorrect matches via aggregate summation calculations. The second gets all possibly likely matches, then removes incorrect matches via an EXCEPT query that uses two dedicated indexes to find the low and high mismatches. Logically, one would expect the brute force to be slow and the indexes one to be fast. Not so. And I have experimented heavily with indexes until I got the best speed. Further, the brute force query doesn't require as many indexes, which means that technically it would yield better overall system performance. Below are the two execution plans. If you can't see them, please let me know and I'll re-post then in landscape orientation / mail them to you. Brute-force query: Index-based exception query: My question is, based on the execution plans, which one look more efficient? I realize that thing may change as my data grows.

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  • Hierarchical Hibernate, how many queries are executed?

    - by ghost1
    So I've been dealing with a home brew DB framework that has some seriously flaws, the justification for use being that not using an ORM will save on the number of queries executed. If I'm selecting all possibile records from the top level of a joinable object hierarchy, how many separate calls to the DB will be made when using an ORM (such as Hibernate)? I feel like calling bullshit on this, as joinable entities should be brought down in one query , right? Am I missing something here? note: lazy initialization doesn't matter in this scenario as all records will be used.

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  • about null values!

    - by user329820
    Hi I have a question that if we declare a variable and then do not set it explicitly to null value then it would be null outomatically ,i mean that the below code will return true or false ? thanks DECLARE @val CHAR(4) If @val = NULL

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  • mysql db connection

    - by Dragster
    hi there i have been searching the web for a connection between my android simulator and a mysql db. I've fount that you can't connect directly but via a webserver. The webserver wil handle my request from my android. I fount the following code on www.helloandroid.com But i don't understand. If i run this code on the simulator nothing happens. The screen stays black. Where does Log.i land. In the android screen or in the error log or somewhere else? Can somebody help me with this code? package app.android.ticket; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.util.ArrayList; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import android.app.Activity; import android.os.Bundle; import android.util.Log; public class fetchData extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); //call the method to run the data retreival getServerData(); } public static final String KEY_121 = "http://www.jorisdek.nl/android/getAllPeopleBornAfter.php"; public fetchData() { Log.e("fetchData", "Initialized ServerLink "); } private void getServerData() { InputStream is = null; String result = ""; //the year data to send ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(); nameValuePairs.add(new BasicNameValuePair("year","1980")); //http post try{ HttpClient httpclient = new DefaultHttpClient(); HttpPost httppost = new HttpPost(KEY_121); httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); HttpResponse response = httpclient.execute(httppost); HttpEntity entity = response.getEntity(); is = entity.getContent(); }catch(Exception e){ Log.e("log_tag", "Error in http connection "+e.toString()); } //convert response to string try{ BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); result=sb.toString(); }catch(Exception e){ Log.e("log_tag", "Error converting result "+e.toString()); } //parse json data try{ JSONArray jArray = new JSONArray(result); for(int i=0;i<jArray.length();i++){ JSONObject json_data = jArray.getJSONObject(i); Log.i("log_tag","id: "+json_data.getInt("id")+ ", name: "+json_data.getString("name")+ ", sex: "+json_data.getInt("sex")+ ", birthyear: "+json_data.getInt("birthyear") ); } }catch(JSONException e){ Log.e("log_tag", "Error parsing data "+e.toString()); } } }

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  • mysql: storing arbitrary data

    - by Hailwood
    Background: I was asking a question on stack overflow regarding creating tables on the fly where this conversation ensued: This smells like a terrible idea! In fact, it smells just like this one. What in the world do you want to use this for? – deceze @deceze: very true, However, How else would you store the contents of these CSV files. They must be stored in mysql for indexing. The only solid fact about them is that they all have a mobile column with a standard format. The CSV can have an arbitrary amount of columns with an arbitrary amount of rows. They can (with no exaggeration) range from a single row, 35 column csv to an 80k row single column CSV. I am open to other ideas. – Hailwood There are many solutions for this, from attribute-value schemas to JSON storage and NoSQL storage. Open a new question about it. Whatever you do though, don't dynamically create tables! – deceze Question: So my question is, What would you say is the best way to store this data? Are you in agreement with deceze about not creating dynamic tables?

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  • How do you determine an acceptable response time for App Engine DB requests?

    - by qiq
    According to this discussion of Google App Engine on Hacker News, A DB (read) request takes over 100ms on the datastore. That's insane and unusable for about 90% of applications. How do you determine what is an acceptable response time for a DB read request? I have been using App Engine without noticing any issues with DB responsiveness. But, on the other hand, I'm not sure I would even know what to look for in that regard :)

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  • Higher speed options for executing very large (20 GB) .sql file in MySQL

    - by Jonogan
    My firm was delivered a 20+ GB .sql file in reponse to a request for data from the gov't. I don't have many options for getting the data in a different format, so I need options for how to import it in a reasonable amount of time. I'm running it on a high end server (Win 2008 64bit, MySQL 5.1) using Navicat's batch execution tool. It's been running for 14 hours and shows no signs of being near completion. Does anyone know of any higher speed options for such a transaction? Or is this what I should expect given the large file size? Thanks

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  • Cursor returns zero rows from query to table

    - by brockoli
    I've created an SQLiteDatabase in my app and populated it with some data. I can connect to my AVD with a terminal and when I issue select * from articles; I get a list of all the rows in my table and everything looks fine. However, in my code when I query my table, I get a cursor back that has my tables columns, but zero rows of data. Here is my code.. mDbHelper.open(); Cursor articles = mDbHelper.fetchAllArticles(); startManagingCursor(articles); Cursor feeds = mDbHelper.fetchAllFeeds(); startManagingCursor(feeds); mDbHelper.close(); int titleColumn = articles.getColumnIndex("title"); int feedIdColumn = articles.getColumnIndex("feed_id"); int feedTitleColumn = feeds.getColumnIndex("title"); /* Check if our result was valid. */ if (articles != null) { int count = articles.getCount(); /* Check if at least one Result was returned. */ if (articles.moveToFirst()) { In the above code, my Cursor articles returns with my 4 columns, but when I call getCount() it returns zero, even though I can see hundreds of rows of data in that table from command line. Any idea what I might be doing wrong here? Also.. here is my code for fetchAllArticles.. public Cursor fetchAllArticles() { return mDb.query(ARTICLES_TABLE, new String[] {ARTICLE_KEY_ROWID, ARTICLE_KEY_FEED_ID, ARTICLE_KEY_TITLE, ARTICLE_KEY_URL}, null, null, null, null, null); } Rob W.

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  • Optimizing an embedded SELECT query in mySQL

    - by Crazy Serb
    Ok, here's a query that I am running right now on a table that has 45,000 records and is 65MB in size... and is just about to get bigger and bigger (so I gotta think of the future performance as well here): SELECT count(payment_id) as signup_count, sum(amount) as signup_amount FROM payments p WHERE tm_completed BETWEEN '2009-05-01' AND '2009-05-30' AND completed > 0 AND tm_completed IS NOT NULL AND member_id NOT IN (SELECT p2.member_id FROM payments p2 WHERE p2.completed=1 AND p2.tm_completed < '2009-05-01' AND p2.tm_completed IS NOT NULL GROUP BY p2.member_id) And as you might or might not imagine - it chokes the mysql server to a standstill... What it does is - it simply pulls the number of new users who signed up, have at least one "completed" payment, tm_completed is not empty (as it is only populated for completed payments), and (the embedded Select) that member has never had a "completed" payment before - meaning he's a new member (just because the system does rebills and whatnot, and this is the only way to sort of differentiate between an existing member who just got rebilled and a new member who got billed for the first time). Now, is there any possible way to optimize this query to use less resources or something, and to stop taking my mysql resources down on their knees...? Am I missing any info to clarify this any further? Let me know... EDIT: Here are the indexes already on that table: PRIMARY PRIMARY 46757 payment_id member_id INDEX 23378 member_id payer_id INDEX 11689 payer_id coupon_id INDEX 1 coupon_id tm_added INDEX 46757 tm_added, product_id tm_completed INDEX 46757 tm_completed, product_id

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  • SQL Server Concatinate string column value to 5 char long

    - by mrp
    Scenario: I have a table1(col1 char(5)); A value in table1 may '001' or '01' or '1'. Requirement: Whatever value in col1, I need to retrive it in 5 char length concatenate with leading '0' to make it 5 char long. Technique I applied: select right(('00000' + col1),5) from table1; I didn't see any reason, why it doesn't work? but it didn't. Can anyone help me, how I can achieve the desired result?

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  • how to model a follower stream in appengine?

    - by molicule
    I am trying to design tables to buildout a follower relationship. Say I have a stream of 140char records that have user, hashtag and other text. Users follow other users, and can also follow hashtags. I am outlining the way I've designed this below, but there are two limitaions in my design. I was wondering if others had smarter ways to accomplish the same goal. The issues with this are The list of followers is copied in for each record If a new follower is added or one removed, 'all' the records have to be updated. The code class HashtagFollowers(db.Model): """ This table contains the followers for each hashtag """ hashtag = db.StringProperty() followers = db.StringListProperty() class UserFollowers(db.Model): """ This table contains the followers for each user """ username = db.StringProperty() followers = db.StringListProperty() class stream(db.Model): """ This table contains the data stream """ username = db.StringProperty() hashtag = db.StringProperty() text = db.TextProperty() def save(self): """ On each save all the followers for each hashtag and user are added into a another table with this record as the parent """ super(stream, self).save() hfs = HashtagFollowers.all().filter("hashtag =", self.hashtag).fetch(10) for hf in hfs: sh = streamHashtags(parent=self, followers=hf.followers) sh.save() ufs = UserFollowers.all().filter("username =", self.username).fetch(10) for uf in ufs: uh = streamUsers(parent=self, followers=uf.followers) uh.save() class streamHashtags(db.Model): """ The stream record is the parent of this record """ followers = db.StringListProperty() class streamUsers(db.Model): """ The stream record is the parent of this record """ followers = db.StringListProperty() Now, to get the stream of followed hastags indexes = db.GqlQuery("""SELECT __key__ from streamHashtags where followers = 'myusername'""") keys = [k,parent() for k in indexes[offset:numresults]] return db.get(keys) Is there a smarter way to do this?

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  • How Can i Create This Complicated Query ?

    - by mTuran
    Hi, I have 3 tables: projects, skills and project_skills. In projects table i hold project's general data. Second table skills i hold skill id and skill name also i have projects_skills table which is hold project's skill relationships. Here is scheme of tables: CREATE TABLE IF NOT EXISTS `project_skills` ( `project_id` int(11) NOT NULL, `skill_id` int(11) NOT NULL, KEY `project_id` (`project_id`), KEY `skill_id` (`skill_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci; CREATE TABLE IF NOT EXISTS `projects` ( `id` int(11) NOT NULL AUTO_INCREMENT, `employer_id` int(11) NOT NULL, `project_title` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `project_description` text COLLATE utf8_turkish_ci NOT NULL, `project_budget` int(11) NOT NULL, `project_allowedtime` int(11) NOT NULL, `project_deadline` datetime NOT NULL, `total_bids` int(11) NOT NULL, `average_bid` int(11) NOT NULL, `created` datetime NOT NULL, `active` tinyint(1) NOT NULL, PRIMARY KEY (`id`), KEY `created` (`created`), KEY `employer_id` (`employer_id`), KEY `active` (`active`), FULLTEXT KEY `project_title` (`project_title`,`project_description`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci AUTO_INCREMENT=3 ; CREATE TABLE IF NOT EXISTS `skills` ( `id` int(11) NOT NULL AUTO_INCREMENT, `category` int(11) NOT NULL, `name` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `seo_name` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `total_projects` int(11) NOT NULL, PRIMARY KEY (`id`), KEY `seo_name` (`seo_name`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci AUTO_INCREMENT=224 ; I want to select projects with related skill names. I think i have to use JOIN but i don't know how can i do. Thanks

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  • why is there extra using where in execution plan of query

    - by user366534
    I see plan of query: EXPLAIN SELECT * FROM `subscribers` WHERE state =4 AND date_added < '2010-12-23 11:47:45' It shows: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subscribers range state_date_added state_date_added 9 NULL 8 Using where Here is indexes of table: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment subscribers 0 PRIMARY 1 subscriber_id A 382039 NULL NULL BTREE subscribers 0 email_list_id 1 email_address A 191019 NULL NULL BTREE subscribers 0 email_list_id 2 list_id A 382039 NULL NULL BTREE subscribers 1 FK_list_id 1 list_id A 10 NULL NULL BTREE subscribers 1 state_date_added 1 state A 12 NULL NULL BTREE subscribers 1 state_date_added 2 date_added A 8128 NULL NULL BTREE The last two lines describes index what is supposed for the query. Why is there in extra column using where? Even If I fetch only state and date_added column, it has in extra column: Using where; Using index. I understand why it has using index, but I don't understand Using where here.

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  • Can somebody suggest good learning source of IMS?

    - by Raja Reddy
    I would like to learn working with IMS, can somebody suggest me a good source? I'm not sure if it matters to say that I have quite good exposure and experience with INSYNC DB2 and QMF. So anything that can depict and explain the advantages and disadvantages over IMS would be really helpful. Thanks for your help beforehand..

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  • importing csv file into pgsql

    - by running4surival
    ok im trying to upload this csv file onto my table in pgsql but im getting this error ERROR: invalid input syntax for integer: "mlname,mfname,slname,sfname,address,postalcode,membershiptype,hphone,email" CONTEXT: COPY members2, line 1, column id: "mlname,mfname,slname,sfname,address,postalcode,membershiptype,hphone,email" i really understand why im getting this error, both my table and my csv file have the same column names

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  • When using a HiLo ID generation strategy, what types should be used to hold Ids?

    - by UpTheCreek
    I'm asking this from a c#/NHibnernate perspective, but it's generally applicable. The concern is that the HiLo strategy goes though id's pretty quickly, and for example a low record-count table (Such as Users) is sharing from the same set of id's as a high record-count table (Such as comments). So you can potentially get to high numbers quicker that with other strategies. So what do people recommend? Code side: int/uint/long/ulong? DBSide: int/bigint? My feeling is to go with longs and bigingts, but would like a sanity check :)

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