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  • is NATURAL JOIN any better than SELECT FROM WHERE in terms of performance ?

    - by ashy_32bit
    Today I got into a debate with my project manager about Cartesian products. He says a 'natural join' is somehow much better than using 'select from where' because the later cause the db engine to internally perform a Cartesian product but the former uses another approach that prevents this. As far as I know, the natural join syntax is not any different in anyway than 'select from where' in terms of performance or meaning, I mean you can use either based on your taste. SELECT * FROM table1,table2 WHERE table1.id=table2.id SELECT * FROM table1 NATURAL JOIN table2 please elaborate about the first query causing a Cartesian product but the second one being somehow more smart

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  • Does the order of the columns in a SELECT statement make a difference?

    - by Frank Computer
    This question was inspired by a previous question posted on SO, "Does the order of the WHERE clause make a differnece?". Would it improve a SELECT statement's performance if the the columns used in the WHERE section are placed at the begining of the SELECT statement? example: SELECT customer.id, transaction.id, transaction.efective_date, transaction.a, [...] FROM customer, transaction WHERE customer.id = transaction.id; I do know that limiting the list of columns to only the needed ones in a SELECT statement improves performance as opposed to using SELECT * because the current list is smaller.

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  • Notification 7 Days Before Payment PHP No Error Message

    - by user1858672
    So I have PHP script running on cron daily. It is suppose to check the date and send an email if it is 7 days before any payments as a reminder. I haven't used PHP in a long time so sorry if the way I did it was ridiculous or something. Thanks a lot. I would say what the problem is but I don't get any error message or anything.. <?php mysqli_connect("xxxxxx", "xxxxxxx", "xxxxxxxxx") or die(mysqli_error()); mysqli_select_db("xxxxxxxxx") or die(mysqli_error()); //Retrieve original payment dates and enter them into an array $result = mysqli_query("SELECT DateCreated FROM UserTable"); $payment_dates = mysqli_fetch_array($result); //Puts original payment date into month-day format $md_payment_dates = substr($payment_dates, 5); //Gets todays date in m-d format and adds 7 days to it $due_date = mktime(0, 0, 0, date("m"), date("d")+7); //Checks if any payment days match today's date. If there are none it script will stop. if (count(preg_grep($due_date, $md_payment_dates)) > 0) { //Retrieves usernames of users that have an invoice due. $users_to_pay = mysqli_fetch_array("SELECT Username IN UserTable WHERE DateCreated = $date"); //Notifies you via email $to = "[email protected]"; $subject = "7 Day Payment Reminder"; $message = "Hi, <br /> The following owe a payment in 7 days : " + $users_to_pay ".<br/> Their payments are due on " + $md_payment_dates " of this year."; mail($to, $subject, $message); exit(); }else{ exit(); } ?>

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  • mysql count(*) left join group by - the number of files in a folder

    - by Flavius
    Hi I have the following tables CREATE TABLE `files` ( `fileid` int(11) NOT NULL AUTO_INCREMENT, `filename` varchar(255) NOT NULL, `filesize` int(11) NOT NULL, `folder` int(11) NOT NULL, PRIMARY KEY (`fileid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; CREATE TABLE `folders` ( `directoryid` int(11) NOT NULL AUTO_INCREMENT, `directoryname` varchar(255) NOT NULL, PRIMARY KEY (`directoryid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; How to get a list of all folders and the number of files they hold, including folders who have no (zero) files? Recursion must not be taken into account. Found it select folders.directoryid, folders.directoryname, count(files.fileid) as no_files from folders left join files on files.folder = folders.directoryid group by folders.directoryid, folders.directoryname I hope it will help someone.

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  • How to limit results by SUM

    - by superspace
    I have a table of events called event. For the purpose of this question it only has one field called date. The following query returns me a number of events that are happening on each date for the next 14 days: SELECT DATE_FORMAT( ev.date, '%Y-%m-%d' ) as short_date, count(*) as date_count FROM event ev WHERE ev.date >= NOW() GROUP BY short_date ORDER BY ev.start_date ASC LIMIT 14 The result could be as follows: +------------+------------+ | short_date | date_count | +------------+------------+ | 2010-03-14 | 1 | | 2010-03-15 | 2 | | 2010-03-16 | 9 | | 2010-03-17 | 8 | | 2010-03-18 | 11 | | 2010-03-19 | 14 | | 2010-03-20 | 13 | | 2010-03-21 | 7 | | 2010-03-22 | 2 | | 2010-03-23 | 3 | | 2010-03-24 | 3 | | 2010-03-25 | 6 | | 2010-03-26 | 23 | | 2010-03-27 | 14 | +------------+------------+ 14 rows in set (0.06 sec) Let's say I want to dislay these events by date. At the same time I only want to display a maximum of 10 at a time. How would I do this? Somehow I need to limit this result by the SUM of the date_count field but I do not know how. Anybody run into this problem before? Any help would be appreciated. Thanks

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  • filter by atributs php script

    - by cosy
    I have the table : id id_products id_atribut name value 1 13 8 autdio 2.1 2 13 9 hdd 200 Gb 3 13 10 cd-rom 2 4 20 8 audio 2.1 the problem is, how can i select from this table where id_products=13 and name="audio" and value="2.1" and name="hdd" and value="200 gb" .... How can i do this?

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  • How can I get the count of orders placed from my database?

    - by user1360564
    I am preparing a chart which will display the number of orders placed for a particular day in the current month and year. I wanted the count of orders placed for each day. I am showing the count of orders on the y-axis and the day on the x-axis. In my database, there is table called "order" in which order data is placed: order date, user_id, order_price, etc. For example, if on 4 July, 10 orders are placed, on 5 july, 20 orders are placed, and so on. How can I get the count of orders placed for day of the current month?

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  • Help doing a dynamic sort?

    - by Kevin
    I have a notifications table which contains different types of notifications for different events. Inside the table is a notifications_type:string column that contains the type of notification, i.e. "foo" or "bar" or "oof" I want the user to be able to select what notifications they want to display, so there are checkboxes below the result that correspond to prefs_display_foo:boolean, prefs_display_bar:boolean in the User model. What is an elegant way for me to set the :conditions in the find to properly display the sorted results? Also, currently I have it as a method in the user, but how would I do it as a has_many :notifications, :conditions = .....

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  • Cakephp Autoconvert find() fields?

    - by Razor Storm
    In cake php I can grab a model's fields by using the find() method. What if I wish to apply a transformation function to the fields? Is there a way to directly accomplish this task? Suppose I have a model called RaceTime with the fields racerId and timeMillis RaceTime +------------+ | Field | +------------+ | id | | racerId | | timeMillis | +------------+ timeMillis is an int specifying how long the race took in milliseconds. Obviously saying a race took 15651 milliseconds isn't very useful to a human reader, and I would wish to convert this to a human readable format. Is there a way to accomplish this directly in find()? Or is the only option to loop through the results after find() finishes?

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  • MYSQL: COUNT with GROUP BY, LEFT JOIN and WHERE clause doesn't return zero values

    - by Paul Norman
    Hi guys, thanks in advance for any help on this topic! I'm sure this has a very simply answer, but I can't seem to find it (not sure what to search on!). A standard count / group by query may look like this: SELECT COUNT(`t2`.`name`) FROM `table_1` `t1` LEFT JOIN `table_2` `t2` ON `t1`.`key_id` = `t2`.`key_id` GROUP BY `t1`.`any_col` and this works as expected, returning 0 if no rows are found. So does: SELECT COUNT(`t2`.`name`) FROM `table_1` `t1` LEFT JOIN `table_2` `t2` ON `t1`.`key_id` = `t2`.`key_id` WHERE `t1`.`another_column` = 123 However: SELECT COUNT(`t2`.`name`) FROM `table_1` `t1` LEFT JOIN `table_2` `t2` ON `t1`.`key_id` = `t2`.`key_id` WHERE `t1`.`another_column` = 123 GROUP BY `t1`.`any_col` only works if there is at least one row in table_1 and fails miserably returning an empty result set if there are zero rows. I would really like this to return 0! Anyone enlighten me on this? Beer can be provided in exchange if you are in London ;-)

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  • get index name within specific table name

    - by AmRoSH
    I need to check if this index not exist in specific table name not in all tables because this select statement select all indexes under this condition. IF NOT EXISTS (SELECT name from sysindexes WHERE name = 'IDX_InsuranceID') CREATE NONCLUSTERED INDEX [IDX_InsuranceID] ON [dbo].[QuoteInsurances] ( [InsuranceID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 80) ON [PRIMARY] GO Thanks,

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  • wanted to get all dates in mysql result

    - by PankajK
    I have mysql table called user(id, name, join_on) join on is a date field what I want is to show in each day how many uses has been created I can use group by but it will only give me the dates when users get added like if date 4/12/10 5 users added 4/13/10 2 users added 4/15/10 7 users added here date 4/14/10 is missing and I want listing of all dates in one month. I have one solution for it by creating another table only for adding date and that table will left join my users table on join_on and will give total result but I don't want to do that as for creating that I need to create and add entries in date table please suggest the different approach for doing so. Thank you.

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  • MSYQL ~ Why does this query only select a single row?

    - by Joe
    SELECT * FROM tbl_houses WHERE (SELECT HousesList FROM tbl_lists WHERE tbl_lists.ID = '123') LIKE CONCAT('% ', tbl_houses.ID, '#') ^ It only selects the row from tbl_houses of the last occuring "tbl_houses.ID" inside tbl_lists.HousesList I need it to select ALL the rows where any ID from tbl_houses exists within tbl_lists.HousesList

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  • Check for duplicate rows in 2 columns before update

    - by user3891378
    I have a table with 4 columns, and I need to check to see if a Column Pair exists before inserting a row into the database: INSERT INTO dbo.tblCallReport_Detail (fkCallReport, fkProductCategory, Discussion, Action) VALUES (?, ?, ?, ?) The pair in question is fkCallReport and fkProductCategory. For example if the row trying to be inserted has fkCallReport = 3 and fkProductCategory = 5, and the database already has both of those values together, it should display an error and ask if they would like to combine the Disuccsion and Action with the current record. Keep in mind I'm doing this in VBA Access 2010 and am still very new.

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  • help with sql query - in access 2007

    - by Gold
    hi i have 2 tables table items has 144602 records table A has 27721 records code in items = BAR8 in A i want to show all records that equal i try this: SELECT Items.Code, A.BAR8 FROM Items INNER JOIN A ON Items.Code = A.BAR8; and i get 28048 records !!! i need to get 27721 , how to do it ? thank's in advance

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  • Entity diagram with tables that have foreign keys that point to a non-PK column do not show relation

    - by Jason Coyne
    I have two tables parent and child. If I make a foreign key on child that points to the primary key of parent, and then make an entity diagram, the relationship is shown correctly. If I make the foreign key point to a different column, the relationship is not shown. I have tried adding indexes to the column, but it does not have an effect. The database is sqlite, but I am not sure if that has an effect since its all hidden behind ADO.net. How do I get the relationship to work correctly?

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  • Removing part of a string in PHP

    - by Nik
    I'm trying to take a query: SHOW TABLES; which will display a bunch of tables with the chat_ prefix. I want to remove the chat_ prefix from the string, format the variable (with a link), and display it. How is this accomplished?

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  • MySql Query to return number of photos in each album

    - by GivenPie
    MY table is set up like this, all I need to do is call a query to my Photos table. I have PhotoID as the primary key and GalleryID as the foreign key to Gallery. How can I could the number of unique PhotoID's for each multiple GalleryIDs. So to speak there are may duplicate GalleryIDs because there are many photos in a gallery. So I just need to could the number of unique PhotoIDs associated with that GalleryID. Can it be done in one query?

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  • MYSQL to UPDATE table if row with 2 specific columns exist or INSERT new row if it does not exist

    - by user2509541
    I have a MYSQL table that looks as follows: id id_jugador id_partido team1 team2 1 2 1 5 2 2 2 2 1 1 3 1 2 0 0 I need to create a query to either INSERT new rows in the table or UPDATE the table. The condition is based on id_jugador and id_partido, meaning that if I wanted to insert id_jugador = 2 and id_partido = 1, then it should just UPDATE the existing row with the new team1 and team2 values I am sending. And dont duplicate the row. However, if I have an entry id_jugador=2 and id_partido=3, since this combination does not exist yet, it should add the new row. I read about the REPLACE INTO but it seems to be unable to check combination of UNIQUE KEYS.

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  • Inserting data into a Database

    - by Erebus
    SO I'm making a "basic" login file where a person logs in and the data that person entered on that form gets transfered to another form aka my database/table. I think the problems is here but I'll post the rest of the code. CREATE FUNCTION dbo.Function4 ( parameter1 int = 5, parameter2 datatype ) RETURNS Table1 TABLE (UserName, Password, Password_Confirmation, Assets) AS BEGIN INSERT INTO Table1 (UserName, Password, Password_Confirmation, Assets) VALUES (a,b,c,d); /*SELECT ... FROM ...*/ RETURN END This is the Login Form using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace Login_Basic { public partial class Form2 : Form { public Form2() { InitializeComponent(); } Form3 Delta = new Form3(); private void label3_Click(object sender, EventArgs e) { } private void Form2_Load(object sender, EventArgs e) { this.Hide(); } private void textBox6_TextChanged(object sender, EventArgs e) { } private void textBox6_KeyPress(object sender, KeyPressEventArgs e) { int i = Convert.ToInt32(e.KeyChar); if (!(Char.IsDigit(e.KeyChar) || Char.IsControl(e.KeyChar) || (e.KeyChar == '.' && this.Text.Contains(".") == false))) e.Handled = true; } private void button1_Click(object sender, EventArgs e) { Delta.Show(); //if (textBox3.Text.Equals("")) //{ // MessageBox.Show("Please enter your username"); //} //else //{ // this.Hide(); //} // if (textBox4.Text.Equals("")) //{ // MessageBox.Show("Please enter your password"); // } // else //{ // this.Hide(); // } // if (textBox5.Text.Equals("")) // { // MessageBox.Show("Please re-enter your password"); // } // else // { // this.Hide(); // } //if (textBox6.Text.Equals("")) //{ // MessageBox.Show("Please enter your amount"); // // } // else // { // this.Hide(); // } } private void button3_Click(object sender, EventArgs e) { this.Hide(); } private void textBox3_TextChanged(object sender, EventArgs e) { } private void textBox4_TextChanged(object sender, EventArgs e) { } private void textBox5_TextChanged(object sender, EventArgs e) { } private void panel2_Paint(object sender, PaintEventArgs e) { /*if (textBox3.Text.Equals("") && textBox4.Text.Equals("") && textBox5.Text.Equals("") && textBox6.Text.Equals("")) { button1.Enabled = false; } else { button1.Enabled = true; }*/ } } } Here's a "Pic" of my database http://s299.photobucket.com/albums/mm305/krsimms123/Code.jpg Thanks in advance (I'll try and check this every few hours so I can help explain anything)

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