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  • What is the difference between check and foreign key?

    - by GigaPr
    Hi, i am quite confused about the difference between a FOREIGN KEY and CHECK constraint. they appear to me to achieve the same result. I mean I could create a table and enforce a Foreign key on another table, but i could create a CHECK to ensure the value in in another table. What is the difference and when to use the one or the other? thanks

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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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  • check if sqlserver is installed on a machine thro C#

    - by Skun
    Hey ! I am making an application which is a user interface to access 2 types of databases - SQLite and MSSQL server. The thing is, SQLite doesnt need to be "installed" since its just a flatfile database, but on the other hand, SQLserver (Express/normal) need to be installed before use. My Question is simple: Is there a way by which i can find out if an instance of SQLserver has been installed on the local machine by using a C# program?

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  • Mysql query problem

    - by Lost_in_code
    Below is a sample table: fruits +-------+---------+ | id | type | +-------+---------+ | 1 | apple | | 2 | orange | | 3 | banana | | 4 | apple | | 5 | apple | | 6 | apple | | 7 | orange | | 8 | apple | | 9 | apple | | 10 | banana | +-------+---------+ Following are the two queries of interest: SELECT * FROM fruits WHERE type='apple' LIMIT 2; SELECT COUNT(*) AS total FROM fruits WHERE type='apple'; // output 6 I want to combine these two queries so that the results looks like this: +-------+---------+---------+ | id | type | total | +-------+---------+---------+ | 1 | apple | 6 | | 4 | apple | 6 | +-------+---------+---------+ The output has to be limited to 2 records but it should also contain the total number of records of the type apple. How can this be done with 1 query?

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  • excel quotes in formula question

    - by I__
    i have a column with this data: IT_AMPH IT_BARB IT_BENZ IT_BUP SOMA i want the column next to it to be literarely =like "*,IT_AMPH,*" =like "*,IT_BARB,*" =like "*,IT_BENZ,*" etc please note that i want the equal signed to be displayed, exactly as shown above what would be the formula for this?

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  • How can I find all records for a model without doing a long list of "OR" conditions?

    - by gomezuk
    I'm having trouble composing a CakePHP find() which returns the records I'm looking for. My associations go like this: User -(has many)- Friends , User -(has many)- Posts I'm trying to display a list of all a user's friends recent posts, in other words, list every post that was created by a friend of the current user logged in. The only way I can think of doing this is by putting all the user's friends' user_ids in a big array, and then looping through each one, so that the find() call would look something like: $posts = $this->Post->find('all',array( 'conditions' => array( 'Post.user_id' => array( 'OR' => array( $user_id_array[0],$user_id_array[1],$user_id_array[2] # .. etc ) ) ) )); I get the impression this isn't the best way of doing things as if that user is popular that's a lot of OR conditions. Can anyone suggest a better alternative?

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  • MySQL Delete Records Older Than X Minutes?

    - by sajanNOPPIX
    I've searched quite a bit and found a few solutions that didn't end up working for me and can't understand why. I have a table with a timestamp column. The MySQL type for this column is 'datetime'. I insert into this table the following from PHP. date('Y-m-d H:i:s') This enters, what looks like the correct value for the MySQL date time. 2012-06-28 15:31:46 I want to use this column to delete rows that are older than say 10 minutes. I'm running the following query, but it's not working. It affects 0 rows. DELETE FROM adminLoginLog WHERE timestamp < (NOW() - INTERVAL 10 MINUTE); Can anyone shed some light as to what I'm doing wrong and why it's not working properly? Thanks. Update: It looks like my first issue is that I'm using DATETIME when I should be using the TIMESTAMP data type. I'm updating my code to do that now. Thanks.

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  • Sorting nested set by name while keep depth integrity

    - by wb
    I'm using the nested set model that'll later be used to build a sitemap for my web site. This is my table structure. create table departments ( id int identity(0, 1) primary key , lft int , rgt int , name nvarchar(60) ); insert into departments (lft, rgt, name) values (1, 10, 'departments'); insert into departments (lft, rgt, name) values (2, 3, 'd'); insert into departments (lft, rgt, name) values (4, 9, 'a'); insert into departments (lft, rgt, name) values (5, 6, 'b'); insert into departments (lft, rgt, name) values (7, 8, 'c'); How can I sort by depth as well as name? I can do select replicate('----', count(parent.name) - 1) + ' ' + node.name , count(parent.name) - 1 as depth , node.lft from departments node , departments parent where node.lft between parent.lft and parent.rgt group by node.name, node.lft order by depth asc, node.name asc; However, that does not match children with their parent for some reason. department lft rgt --------------------------- departments 0 1 ---- a 1 4 ---- d 1 2 -------- b 2 5 -------- c 2 7 As you can see, department 'd' has department 'a's children! Thank you.

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  • Improving performance for WRITE operation on Oracle DB in Java

    - by Lucky
    I've a typical scenario & need to understand best possible way to handle this, so here it goes - I'm developing a solution that will retrieve data from a remote SOAP based web service & will then push this data to an Oracle database on network. Also, this will be a scheduled task that will execute every 15 minutes. I've event queues on remote service that contains the INSERT/UPDATE/DELETE operations that have been done since last retrieval, & once I retrieve the events for last 15 minutes, it again add events for next retrieval. Now, its just pushing data to Oracle so all my interactions are INSERT & UPDATE statements. There are around 60 tables on Oracle with some of them having 100+ columns. Moreover, for every 15 minutes cycle there would be around 60-70 Inserts, 100+ Updates & 10-20 Deletes. This will be an executable jar file that will terminate after operation & will again start on next 15 minutes cycle. So, I need to understand how should I handle WRITE operations (best practices) to improve performance for this application as whole ? Current Test Code (on every cycle) - Connects to remote service to get events. Creates a connection with DB (single connection object). Identifies the type of operation (INSERT/UPDATE/DELETE) & table on which it is done. After above, calls the respective method based on type of operation & table. Uses Preparedstatement with positional parameters, & retrieves each column value from remote service & assigns that to statement parameters. Commits the statement & returns to get event class to process next event. Above is repeated till all the retrieved events are processed after which program closes & then starts on next cycle & everything repeats again. Thanks for help !

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  • Cursor loops; How to perform something at start/end of loop 1 time only?

    - by James.Elsey
    I've got the following in one of my Oracle procedures, I'm using it to generate XML -- v_client_addons is set to '' to avoid null error OPEN C_CLIENT_ADDONS; LOOP FETCH C_CLIENT_ADDONS INTO CLIENT_ADDONS; EXIT WHEN C_CLIENT_ADDONS%NOTFOUND; BEGIN v_client_addons := v_client_addons || CLIENT_ADDONS.XML_DATA; END; END LOOP; CLOSE C_CLIENT_ADDONS; -- Do something later with v_client_addons The loop should go through my cursor and pick out all of the XML values to display, such as : <add-on name="some addon"/> <add-on name="another addon"/> What I would like to achieve is to have an XML start/end tag inside this loop, so I would have the following output <addons> <add-on name="some addon"/> <add-on name="another addon"/> </addons> How can I do this without having the <addons> tag after every line? If there are no addons in the cursor (cursor is empty), then I would like to skip this part enitrely

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  • Join with table and sub query in oracle

    - by Amandeep
    I dont understand what is wrong with this query it is giving me compile time error of command not ended properly.The inner query is giving me 4 records can any body help me out. select WGN3EVENTPARTICIPANT.EVENTUID from (Select WGN_V_ADDRESS_1.ADDRESSUID1 as add1, WGN_V_ADDRESS_1.ADDRESSUID2 as add2 from WGN3USER inner join WGN_V_ADDRESS_1 on WGN_V_ADDRESS_1.USERID=wgn3user.USERID where WGN3USER.USERNAME='FIRMWIDE\khuraj' ) as ta ,WGN3EVENTPARTICIPANT where (ta.ADDRESSUID1=WGN3EVENTPARTICIPANT.ADDRESSUID1) AND (ta.ADDRESSUID2=WGN3EVENTPARTICIPANT.ADDRESSUID2) I am running it in oracle. Thanks Amandeep

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  • How do I specify a default value in a MS Access query?

    - by jheddings
    I have three tables similar to the following: tblInvoices: Number | Date | Customer tblInvDetails: Invoice | Quantity | Rate | Description tblPayments: Invoice | Date | Amount I have created a query called exInvDetails that adds an Amount column to tblInvDetails: SELECT tblInvDetails.*, [tblInvDetails.Quantity]*[tblInvDetails.Rate]* AS Amount FROM tblInvDetails; I then created a query exInvoices to add Total and Balance columns to tblInvoices: SELECT tblInvoices.*, (SELECT Sum(exInvDetails.Amount) FROM exInvDetails WHERE exInvDetails.Invoice = tblInvoices.Number) AS Total, (SELECT Sum(tblPayments.Amount) FROM tblPayments WHERE tblPayments.Invoice = tblInvoices.Number) AS Payments, (Total-Payments) AS Balance FROM tblInvoices; If there are no corresponding payments in tblPayments, the fields are null instead of 0. Is there a way to force the resulting query to put a 0 in this column?

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  • MSSQL. Compare columns in two tables.

    - by maxt3r
    Hi, i've recently done a migration from a really old version of some application to the current version and i faced some problems while migrating databases. I need a query that could help me to compare columns in two tables. I mean not the data in rows, i need to compare the columns itself to figure out, what changes in table structure i've missed.

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  • Create an index only on certain rows in mysql

    - by dhruvbird
    So, I have this funny requirement of creating an index on a table only on a certain set of rows. This is what my table looks like: USER: userid, friendid, created, blah0, blah1, ..., blahN Now, I'd like to create an index on: (userid, friendid, created) but only on those rows where userid = friendid. The reason being that this index is only going to be used to satisfy queries where the WHERE clause contains "userid = friendid". There will be many rows where this is NOT the case, and I really don't want to waste all that extra space on the index. Another option would be to create a table (query table) which is populated on insert/update of this table and create a trigger to do so, but again I am guessing an index on that table would mean that the data would be stored twice. How does mysql store Primary Keys? I mean is the table ordered on the Primary Key or is it ordered by insert order and the PK is like a normal unique index? I checked up on clustered indexes (http://dev.mysql.com/doc/refman/5.0/en/innodb-index-types.html), but it seems only InnoDB supports them. I am using MyISAM (I mention this because then I could have created a clustered index on these 3 fields in the query table). I am basically looking for something like this: ALTER TABLE USERS ADD INDEX (userid, friendid, created) WHERE userid=friendid

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  • How to use php variables (arrays) in mysql select statements?

    - by davidconn
    Hi everybody, How do you use a php variable (array) inside a mysql select statement? I am designing an auction site and currently working on a page that lets people view a list of all the current bids for an item. I want to display 3 columns: amountbid - the amount each bidder has bid for the item (held in tblbid) bidderid - the id of each bidder who has bid (found in tbluser) total_positivity_feedback - how many users have left positive feedback for the bidder (calculated from tblfeedback) To find the 'amount' and the 'bidderid' columns i pass the essayid URL parameter from the previous page. This works fine. Despite this, i can't display the total_positivity_feedback column for the various users who have made each bid. My mysql query looks like this: select tblbid.bidderid, tblbid.amount, (select count(tblfeedback.feedbackid) from tblfeedback WHERE tblfeedback.writerid = "ARRAY VARIABLE GOES HERE") AS total_positivity_feedback FROM tblbid WHERE tblbid.essayid = $essayid_bids I assume that the only way to accomplish this is to make the variable contain the bidderid's of those people who bid for that particular essay? I can't seem to work out how to do this tho?!? Many thanks for your help

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