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  • MySQL - Join as zero if record Not IN

    - by Zurahn
    To explain by example, take two tables, A and B Table A id foo 1 x 2 y 3 z Table B id aid bar 1 3 50 2 1 100 An example join SELECT foo, bar FROM a, b WHERE a.id = b.aid; Garners a result of foo bar z 50 x 100 What I would like to do is get all values of foo and for any instances where there isn't a corresponding bar value, return 0 for that column. My best guess was something along the lines of SELECT foo, bar AS br FROM a, b WHERE a.id = b.aid OR a.id NOT IN (SELECT aid FROM b); But that returns duplicates and non-zero values for bar. Possible?

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  • Does introducing foreign keys to MySQL reduce performance

    - by Tam
    I'm building Ruby on Rails 2.3.5 app. By default, Ruby on Rails doesn't provide foreign key contraints so I have to do it manually. I was wondering if introducing foreign keys reduces query performance on the database side enough to make it not worth doing. Performance in this case is my first priority as I can check for data consistency with code. What is your recommendation in general? do you recommend using foreign keys? and how do you suggest I should measure this?

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  • How to 'insert if not exists' in MySQL?

    - by warren
    I started by googling, and found this article which talks about mutex tables. I have a table with ~14 million records. If I want to add more data in the same format, is there a way to ensure the record I want to insert does not already exist without using a pair of queries (ie, one query to check and one to insert is the result set is empty)? Does a unique constraint on a field guarantee the insert will fail if it's already there? It seems that with merely a constraint, when I issue the insert via php, the script croaks.

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  • PHP Code- How to check duplicate entries in Mysql Database

    - by yash bhavnani
    Hi guys, I am working on Google checkout API notification URL. I want to apply a check in my php code which will see if transaction ID present in transaction table of my DB, it will exit not process. I am struggling into applying here. Can somebody help? I want to check if trasaction ID exists in table of DB it will exit, it will not process: *case "new-order-notification": $sql = "update transactions set remote_trans_id=\"".$_REQUEST["google-order-number"]."\", updated=now() where id=".$_REQUEST["shopping-cart_items_item-1_merchant-item-id"]." "; execute($sql, $conn); break;* Regards

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  • mysql data being inserted twice via php

    - by Jascha
    I can't for the life of me figure out why this function is causing multiple entries into my database table... When I run the function I end up with two records stacked on top of each one second apart here is the function: function generate_signup_token(){ $connection = new DB_Connect(); // <--- my database connection class $ip = mysql_real_escape_string($_SERVER['REMOTE_ADDR']); $sign_up_token = uniqid(mt_rand(), true); $_SESSION['signup_token'] = $sign_up_token; $sign_up_token = mysql_real_escape_string($sign_up_token); $query = "INSERT INTO `token_manager` (`ip_address`, `signup_token`) VALUES ('$ip', '$sign_up_token')"; mysql_query($query); } generate_signup_token();

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  • How do i know if a mysql table is using myISAM or InnoDB Engine

    - by kamal
    I want to confirm if the statement below is indeed true: There is no way to specify a storage engine for a certain database, only for single tables, You can, however, specify a storage engine to be used during one session with: SET storage_engine=InnoDB; so you don't have to specify it for each table. How do i confirm, if indeed all the tables are using InnoDB All the tables were using myISAM.

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  • Mysql Avg function for recent 15 records by date (order date desc) in every symbol

    - by venkatesh
    i am trying to create a statement in sql (for a table which holds stock symbols and price on specified date) with avg of 5 day price and avg of 15 days price for each symbol. table description: symbol open high close date the average price is calculated from last 5 days and last 15 days. i tried this for getting 1 symbol: SELECT avg(close), avg(`trd_qty`) FROM (select * from cashmarket WHERE symbol = \'hdil\' order by `M_day` desc limit 0,15 ) s ...but I couldn't get the desired the list for showing avg values for all symbols.

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  • Partitioning a table in mysql after creation

    - by erik
    I have a table with a bunch of data already in it. I know how to create a partitioned table or alter an already existing partitioned table, but can I add partitions to a table after it has been created, has data in it, without losing the data? The other option is to dump all the data, recreate the table with the partitions and then insert it all back it. Is that the only way? Thanks.

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  • MYSQL, Subquery Reference in Union

    - by christian
    Is there any way to reference a subquery in a union? I am trying to do something like the following, and would like to avoid a temporary table, but the subquery will be drawn from a much larger dataset so it makes sense to only do it once.. SELECT * FROM (SELECT * FROM ads WHERE state='FL' AND city='Maitland' AND page='home' ORDER BY RAND()) AS sq WHERE spot = 'full-banner' LIMIT 1 UNION SELECT * FROM sq WHERE spot = 'leaderboard' LIMIT 1 UNION SELECT * FROM sq WHERE spot = 'rectangle1' LIMIT 1 UNION SELECT * FROM sq WHERE spot = 'rectangle2' LIMIT 1 .... etc,, It's a shame that DISTINCT can't be specified for a single column of a result set.

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  • MySQL - Selecting the top occurring entries

    - by RC
    Hi, Should be a simple one. Database is mydb. One of the columns is mydata. What SELECT query do I need in order to select the top 3 occurring results from mydata, but sorted alphabetically? For example, if my data is this: mydata ====== kilo (x 1 occurrence) lima (x 9 occurrences) golf (x 5 occurrences) echo (x 9 occurrences) zulu (x 8 occurrences) How do I get it to return "echo, lima, zulu", which are the top three frequently occurring entries sorted alphabetically? Thanks! EDIT: Just to add, they need to be distinct entries. Thanks!

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  • mysql data read returning 0 rows from class

    - by Neo
    I am implementing a database manager class within my app, mainly because there are 3 databases to connect to one being a local one. However the return function isn't working, I know the query brings back rows but when it is returned by the class it has 0. What am I missing? public MySqlDataReader localfetchrows(string query, List<MySqlParameter> dbparams = null) { using (var conn = connectLocal()) { Console.WriteLine("Connecting local : " + conn.ServerVersion); MySqlCommand sql = conn.CreateCommand(); sql.CommandText = query; if (dbparams != null) { if (dbparams.Count > 0) { sql.Parameters.AddRange(dbparams.ToArray()); } } MySqlDataReader reader = sql.ExecuteReader(); Console.WriteLine("Reading data : " + reader.HasRows + reader.FieldCount); return reader; /* using (MySqlCommand sql = conn.CreateCommand()) { sql.CommandText = query; if (dbparams != null) { if (dbparams.Count > 0) { sql.Parameters.AddRange(dbparams.ToArray()); } } MySqlDataReader reader = sql.ExecuteReader(); Console.WriteLine("Reading data : " + reader.HasRows + reader.FieldCount); sql.Parameters.Clear(); return reader; }*/ } } And the code to get the results query = @"SELECT jobtypeid, title FROM jobtypes WHERE active = 'Y' ORDER BY title ASC"; //parentfrm.jobtypes = db.localfetchrows(query); var rows = db.localfetchrows(query); Console.WriteLine("Reading data : " + rows.HasRows + rows.FieldCount); while (rows.Read()){ } These scripts return the following : Connecting local : 5.5.16 Reading data : True2 Reading data : False0

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  • mysql conditional query - complicated!

    - by emre
    i want to get distinct values for a field, let say: field1... ok this needs a query like: "select distint(field1) from table" however for some records, field1 is empty and there is another column that is an alternative to field1, which is field2. now; for the records where field1 is empty i need to use the value of field2. i think i need sort of a conditional select statement with if control something like: "select distinct( (if(field1!='') field1 else field2) ) from table" but i have no idea on how to write it. any help is appricated...

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  • mysql: get all rows into 1 column

    - by andufo
    hi, i have 3 tables: post (id_post, title) tag (id_tag, name) post_tag (id_post_tag, id_post, id_tag) Lets suppose that id_post 3 has 4 linked tags 1,2,3,4 (soccer, basket, tennis and golf). Is there a way to return something like this in ONE row? col 1 id_post = 3 col 2 tags = soccer basket tennis golf Thanks

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  • MySQL Update query with left join and group by

    - by Rob
    I am trying to create an update query and making little progress in getting the right syntax. The following query is working: SELECT t.Index1, t.Index2, COUNT( m.EventType ) FROM Table t LEFT JOIN MEvents m ON (m.Index1 = t.Index1 AND m.Index2 = t.Index2 AND (m.EventType = 'A' OR m.EventType = 'B') ) WHERE (t.SpecialEventCount IS NULL) GROUP BY t.Index1, t.Index2 It creates a list of triplets Index1,Index2,EventCounts. It only does this for case where t.SpecialEventCount is NULL. The update query I am trying to write should set this SpecialEventCount to that count, i.e. COUNT(m.EventType) in the query above. This number could be 0 or any positive number (hence the left join). Index1 and Index2 together are unique in Table t and they are used to identify events in MEvent. How do I have to modify the select query to become an update query? I.e. something like UPDATE Table SET SpecialEventCount=COUNT(m.EventType)..... but I am confused what to put where and have failed with numerous different guesses.

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  • How to refactor this MySQL code?

    - by Jader Dias
    SELECT * ( SELECT * FROM `table1` WHERE `id` NOT IN ( SELECT `id` FROM `table2` WHERE `col4` = 5 ) group by `col2` having sum(`col3`) > 0 UNION SELECT * FROM `table1` WHERE `id` NOT IN ( SELECT `id` FROM `table2` WHERE `col4` = 5 ) group by `col2` having sum(`col3`) = 0 ) t1; For readability and performance reasons, I think this code could be refactored. But how?

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  • block write access to table from an application in mysql

    - by hoberion
    Hello, We have a CMS plugin that writes statistics to 1 table, this creates performance issues on the entire platform. We decided to use another statistics plugin which can connect to a different database server (the first plugin couldn't!) however we need parts of the first plugin. I want to lock the statistics table to prevent misusage (not allowed to drop it by the developer) So I was wondering if a lock table could do this or if I can implement some sort of read only table

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  • Add results from MySQL?

    - by NardCake
    Not quite sure how descriptive that title was but this is what I want to do. I scripted a URL shortener today and it's working fine, I just want to add some stats on the bottom of it saying how many links there are and how many clicks there are. Now everytime a user clicks one of the links it +1 the column in the database then it redirects the user. I want to query that and add all of those numbers together from each row. I attempted a while loop which im not surprised didn't work: while($rows = mysql_fetch_assoc($check_count)){ $clicks = $rows['clicks']; $clicks = $clicks+$clicks; } If you don't understand please ask and if you do understand it means alot for any response!

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  • mysql left join

    - by user1019538
    I have two table one is index and another is the price structure as under table : index : column : trandate ,indexcode Table : price : Column: trandate,symbol,price i want to know the missing price. I issue the query select i.trandate,i.indexcode,p.trandate,p.price from index i left join price p on i.trandate = p.trandate where p.symbol='ABC' and indexcode="New" the above query does not show the null date even though various price in missing in price table. Only reason i understand is that the index table does not have the symbol field that's why...but as per theory if you want to show all the rows of one table and only the match value of another table then use the left or right join query...please anybody can help

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  • Table for each region in MySQL

    - by King Wu
    There are four regions with more than one million records total. Should I create a table with a region column or a table for each region and combine them to get the top ranks? If I combine all four regions, none of my columns will be unique so I will need to also add an id column for my primary key. Otherwise, name, accountId & characterId would be candidate keys or should I just add an id column anyways. Table: ---------------------------------------------------------------- | name | accountId | iconId | level | characterId | updateDate | ----------------------------------------------------------------

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  • Need help optimizing MYSQL query with join

    - by makeee
    I'm doing a join between the "favorites" table (3 million rows) the "items" table (600k rows). The query is taking anywhere from .3 seconds to 2 seconds, and I'm hoping I can optimize it some. Favorites.faver_profile_id and Items.id are indexed. Instead of using the faver_profile_id index I created a new index on (faver_profile_id,id), which eliminated the filesort needed when sorting by id. Unfortunately this index doesn't help at all and I'll probably remove it (yay, 3 more hours of downtime to drop the index..) Any ideas on how I can optimize this query? In case it helps: Favorite.removed and Item.removed are "0" 98% of the time. Favorite.collection_id is NULL about 80% of the time. SELECT `Item`.`id`, `Item`.`source_image`, `Item`.`cached_image`, `Item`.`source_title`, `Item`.`source_url`, `Item`.`width`, `Item`.`height`, `Item`.`fave_count`, `Item`.`created` FROM `favorites` AS `Favorite` LEFT JOIN `items` AS `Item` ON (`Item`.`removed` = 0 AND `Favorite`.`notice_id` = `Item`.`id`) WHERE ((`faver_profile_id` = 1) AND (`collection_id` IS NULL) AND (`Favorite`.`removed` = 0) AND (`Item`.`removed` = '0')) ORDER BY `Favorite`.`id` desc LIMIT 50;

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