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  • How do I select a random record efficiently in MySQL?

    - by user198729
    mysql> EXPLAIN SELECT * FROM urls ORDER BY RAND() LIMIT 1; +----+-------------+-------+------+---------------+------+---------+------+-------+---------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+---------------+------+---------+------+-------+---------------------------------+ | 1 | SIMPLE | urls | ALL | NULL | NULL | NULL | NULL | 62228 | Using temporary; Using filesort | +----+-------------+-------+------+---------------+------+---------+------+-------+---------------------------------+ The above doesn't qualify as efficient,how should I do it properly?

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  • Select count() max() Date HELP!!! mysql oracle

    - by DAVID
    Hi guys i have a table with shifts history along with emp ids im using this code to retrieve a list of employees and their total shifts by specifying the range to count from: SELECT ope_id, count(ope_id) FROM operator_shift WHERE ope_shift_date >=to_date( '01-MAR-10','dd-mon-yy') and ope_shift_date <= to_date('31-MAR-10','dd-mon-yy') GROUP BY OPE_ID which gives OPE_ID COUNT(OPE_ID) 1 14 2 7 3 6 4 6 5 2 6 5 7 2 8 1 9 2 10 4 10 rows selected. NOW how do i choose the employee with the highest no of shifts under the specified range date, please this is really important

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  • writting an sql query

    - by Praveen Prasad
    iam having 2 tables table Items Table (this table holds all items iam having) itemId --------- Item1 Item2 Item3 Item4 Item5 table 2 users_item relation UserId || ItemId 1 || Item1 1 || Item2 userId one has stored 2 items Item1,Item2. Now i want to write a query on table1 (Items table) so that it displays all items which user1 has NOT chosen.

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  • Best .NET Solution for Frequently Changed Database

    - by sestocker
    I am currently architecting a small CRUD applicaton. Their database is a huge mess and will be changing frequently over the course of the next 6 months to a year. What would you recommend for my data layer: 1) ORM (if so, which one?) 2) Linq2Sql 3) Stored Procedures 4) Parametrized Queries I really need a solution that will be dynamic enough (both fast and easy) where I can replace tables and add/delete columns frequently. Note: I do not have much experience with ORM (only a little SubSonic) and generally tend to use stored procedures so maybe that would be the way to go. I would love to learn Ling2Sql or NHibernate if either would allow for the situation I've described above.

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  • my output parameters are always null when i use BeginExecuteNonQuery

    - by CharlesO
    I have a stored procedure that returns a varchar(160) as an output parameter of a stored procedure. Everything works fine when i use ExecuteNonQuery, i always get back the expected value. However, once i switch to use BeginExecuteNonQuery, i get a null value for the output. I am using connString + "Asynchronous Processing=true;" in both cases. Sadly the BeginExecuteNonQuery is about 1.5 times faster in my case...but i really need the output parameter. Thanks!

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  • Database design advice needed.

    - by user346271
    Hi all, I'm a lone developer for a telecoms company, and am after some database design advice from anyone with a bit of time to answer. I am inserting into one table ~2 million rows each day, these tables then get archived and compressed on a monthly basis. Each monthly table contains ~15,000,000 rows. Although this is increasing month on month. For every insert I do above I am combining the data from rows which belong together and creating another "correlated" table. This table is currently not being archived, as I need to make sure I never miss an update to the correlated table. (Hope that makes sense) Although in general this information should remain fairly static after a couple of days of processing. All of the above is working perfectly. However my company now wishes to perform some stats against this data, and these tables are getting too large to provide the results in what would be deemed a reasonable time. Even with the appropriate indexes set. So I guess after all the above my question is quite simple. Should I write a script which groups the data from my correlated table into smaller tables. Or should I store the queries result sets in something like memcache? I'm already using mysqls cache, but due to having limited control over how long the data is stored for, it's not working ideally. The main advantages I can see of using something like memcache: No blocking on my correlated table after the query has been cashed. Greater flexibility of sharing the collected data between the backend collector and front end processor. (i.e custom reports could be written in the backend and the results of these stored in the cache under a key which then gets shared with anyone who would want to see the data of this report) Redundancy and scalability if we start sharing this data with a large amount of customers. The main disadvantages I can see of using something like memcache: Data is not persistent if machine is rebooted / cache is flushed. The main advantages of using MySql Persistent data. Less code changes (although adding something like memcache is trivial anyway) The main disadvantages of using MySql Have to define table templates every time I want to store provide a new set of grouped data. Have to write a program which loops through the correlated data and fills these new tables. Potentially will still grow slower as the data continues to be filled. Apologies for quite a long question. It's helped me to write down these thoughts here anyway, and any advice/help/experience with dealing with this sort of problem would be greatly appreciated. Many thanks. Alan

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  • Simple aggregating query very slow in PostgreSql, any way to improve?

    - by Ash
    HI I have a table which holds files and their types such as CREATE TABLE files ( id SERIAL PRIMARY KEY, name VARCHAR(255), filetype VARCHAR(255), ... ); and another table for holding file properties such as CREATE TABLE properties ( id SERIAL PRIMARY KEY, file_id INTEGER CONSTRAINT fk_files REFERENCES files(id), size INTEGER, ... // other property fields ); The file_id field has an index. The file table has around 800k lines, and the properties table around 200k (not all files necessarily have/need a properties). I want to do aggregating queries, for example find the average size and standard deviation for all file types. But it's very slow - around 70 seconds for the latter query. I understand it needs a sequential scan, but still it seems too much. Here's the query SELECT f.filetype, avg(size), stddev(size) FROM files as f, properties as pr WHERE f.id = pr.file_id GROUP BY f.filetype; and the explain HashAggregate (cost=140292.20..140293.94 rows=116 width=13) (actual time=74013.621..74013.954 rows=110 loops=1) -> Hash Join (cost=6780.19..138945.47 rows=179564 width=13) (actual time=1520.104..73156.531 rows=179499 loops=1) Hash Cond: (f.id = pr.file_id) -> Seq Scan on files f (cost=0.00..108365.41 rows=1140941 width=9) (actual time=0.998..62569.628 rows=805270 loops=1) -> Hash (cost=3658.64..3658.64 rows=179564 width=12) (actual time=1131.053..1131.053 rows=179499 loops=1) -> Seq Scan on properties pr (cost=0.00..3658.64 rows=179564 width=12) (actual time=0.753..557.171 rows=179574 loops=1) Total runtime: 74014.520 ms Any ideas why it is so slow/how to make it faster?

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  • Query crashes MS Access

    - by user284651
    THE TASK: I am in the process of migrating a DB from MS Access to Maximizer. In order to do this I must take 64 tables in MS ACCESS and merge them into one. The output must be in the form of a TAB or CSV file. Which will then be imported into Maximizer. THE PROBLEM: Access is unable to perform a query that is so complex it seems, as it crashes any time I run the query. ALTERNATIVES: I have thought about a few alternatives, and would like to do the least time-consuming one, out of these, while also taking advantage of any opportunities to learn something new. Export each table into CSVs and import into SQLight and then make a query with it to do the same as what ACCESS fails to do (merge 64 tables). Export each table into CSVs and write a script to access each one and merge the CSVs into a single CSV. Somehow connect to the MS ACCESS DB (API), and write a script to pull data from each table and merge them into a CSV file. QUESTION: What do you recommend?

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  • Count total number of callers?

    - by Kristopher Ives
    I'm currently doing this query to find the guy who makes the most calls: SELECT `commenter_name`, COUNT(*) AS `calls` FROM `comments` GROUP BY `commenter_name` ORDER BY `calls` LIMIT 1 What I want now is to be able to find out how many total unique callers. I tried using DISTINCT but I didn't get anywhere.

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  • Has anyone ever successfully make index merge work for MySQL?

    - by user198729
    Setup: mysql> create table t(a integer unsigned,b integer unsigned); mysql> insert into t(a,b) values (1,2),(1,3),(2,4); mysql> create index i_t_a on t(a); mysql> create index i_t_b on t(b); mysql> explain select * from t where a=1 or b=4; +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | 1 | SIMPLE | t | ALL | i_t_a,i_t_b | NULL | NULL | NULL | 3 | Using where | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ Is there something I'm missing? Update mysql> explain select * from t where a=1 or b=4; +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ | 1 | SIMPLE | t | ALL | i_t_a,i_t_b | NULL | NULL | NULL | 1863 | Using where | +----+-------------+-------+------+---------------+------+---------+------+------+-------------+ Version: mysql> select version(); +----------------------+ | version() | +----------------------+ | 5.1.36-community-log | +----------------------+ Has anyone ever successfully make index merge work for MySQL? I'll be glad to see successful stories here:)

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  • MySQL - Find entries that refer to a specified index.

    - by Conor H
    Hi, So I have a booking system where I have a 'lesson_type' table with 'lesson_type_id' as PK. I have a constraint in place here so I can't delete a lesson_type if there are bookings made for that lesson_type. I would like to be able to determine if this lesson_type_id is being referred to by any entries in the bookings table (or any other table for that matter) so I can notify the user gracefully. i.e. not have a mysql error be thrown when they try and delete a record. What kind of query would I use for this? Thanks.

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  • How to get common field in ten tables with different field name

    - by Fero
    Hi all, I am having a common field in ten tables with different field name. example: table1: t1_id     t1_location 1         india 2         china 3         america table2: t2_id     t2_location 4         london 5         australia 6         america Now my o/p should be: location india china america london australia How should i get that using mysql query. thanks in advance

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  • Running an application from an USB device...

    - by Workshop Alex
    I'm working on a proof-of-concept application, containing a WCF service with console host and client, both on a single USB device. On the same device I will also have the client application which will connect to this service. The service uses the entity framework to connect to the database, which in this POC will just return a list of names. If it works, it will be used for a larger project. Creating the client and service was easy and this works well from USB. But getting the service to connect to the database isn't. I've found this site, suggesting that I should modify machine.config but that stops the XCopy deployment. This project cannot change any setting of the PC, so this suggestion is bad. I cannot create a deployment setup either. The whole thing just needs to run from USB disk. So, how do I get it to run? (The service just selects a list of names from the database, which it returns to the client. If this POC works, it will do far more complex things!)

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  • how do I integrate the aspnet_users table that comes with asp.net membership into my existing databa

    - by ooo
    i have a database that already has a users table COLUMNS: userID - int loginName - string First - string Last - string i just installed the asp.net membership table. Right now all of my tables are joined into my users table foreign keyed into the "userId" field How do i integrate asp.net_users table into my schema? here are the ideas i thought of: Add a membership_id field to my users table and on new inserts, include that new field in my users table. This seems like the cleanest way as i dont need to break any existing relationships. break all existing relationship and move all of the fields in my user table into the asp.net_users table. This seems like a pain but ultimately will lead to the most simple, normalized solution any thoughts?

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  • how to reverse the order of words in query or c#

    - by Ranjana
    i have stored in the database as location India,Tamilnadu,Chennai,Annanagar while i bind in the grid view it ll be displaying as 'India,Tamilnadu,Chennai,Annanagar' this format. but i need to be displayed as 'Annanagar,Chennai,Tamilnadu,India' in this format. how to perform this reverse order in query or in c#

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  • Databinding in combo box

    - by muralekarthick
    Hi I have two forms, and a class, queries return in Stored procedure. Stored Procedure: ALTER PROCEDURE [dbo].[Payment_Join] @reference nvarchar(20) AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; -- Insert statements for procedure here SELECT p.iPaymentID,p.nvReference,pt.nvPaymentType,p.iAmount,m.nvMethod,u.nvUsers,p.tUpdateTime FROM Payment p, tblPaymentType pt, tblPaymentMethod m, tblUsers u WHERE p.nvReference = @reference and p.iPaymentTypeID = pt.iPaymentTypeID and p.iMethodID = m.iMethodID and p.iUsersID = u.iUsersID END payment.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; using System.Data.SqlClient; using System.Windows.Forms; namespace Finance { class payment { string connection = global::Finance.Properties.Settings.Default.PaymentConnectionString; #region Fields int _paymentid = 0; string _reference = string.Empty; string _paymenttype; double _amount = 0; string _paymentmethod; string _employeename; DateTime _updatetime = DateTime.Now; #endregion #region Properties public int paymentid { get { return _paymentid; } set { _paymentid = value; } } public string reference { get { return _reference; } set { _reference = value; } } public string paymenttype { get { return _paymenttype; } set { _paymenttype = value; } } public string paymentmethod { get { return _paymentmethod; } set { _paymentmethod = value; } } public double amount { get { return _amount;} set { _amount = value; } } public string employeename { get { return _employeename; } set { _employeename = value; } } public DateTime updatetime { get { return _updatetime; } set { _updatetime = value; } } #endregion #region Constructor public payment() { } public payment(string refer) { reference = refer; } public payment(int paymentID, string Reference, string Paymenttype, double Amount, string Paymentmethod, string Employeename, DateTime Time) { paymentid = paymentID; reference = Reference; paymenttype = Paymenttype; amount = Amount; paymentmethod = Paymentmethod; employeename = Employeename; updatetime = Time; } #endregion #region Methods public void Save() { try { SqlConnection connect = new SqlConnection(connection); SqlCommand command = new SqlCommand("payment_create", connect); command.CommandType = CommandType.StoredProcedure; command.Parameters.Add(new SqlParameter("@reference", reference)); command.Parameters.Add(new SqlParameter("@paymenttype", paymenttype)); command.Parameters.Add(new SqlParameter("@amount", amount)); command.Parameters.Add(new SqlParameter("@paymentmethod", paymentmethod)); command.Parameters.Add(new SqlParameter("@employeename", employeename)); command.Parameters.Add(new SqlParameter("@updatetime", updatetime)); connect.Open(); command.ExecuteScalar(); connect.Close(); } catch { } } public void Load(string reference) { try { SqlConnection connect = new SqlConnection(connection); SqlCommand command = new SqlCommand("Payment_Join", connect); command.CommandType = CommandType.StoredProcedure; command.Parameters.Add(new SqlParameter("@Reference", reference)); //MessageBox.Show("ref = " + reference); connect.Open(); SqlDataReader reader = command.ExecuteReader(); while (reader.Read()) { this.reference = Convert.ToString(reader["nvReference"]); // MessageBox.Show(reference); // MessageBox.Show("here"); // MessageBox.Show("payment type id = " + reader["nvPaymentType"]); // MessageBox.Show("here1"); this.paymenttype = Convert.ToString(reader["nvPaymentType"]); // MessageBox.Show(paymenttype.ToString()); this.amount = Convert.ToDouble(reader["iAmount"]); this.paymentmethod = Convert.ToString(reader["nvMethod"]); this.employeename = Convert.ToString(reader["nvUsers"]); this.updatetime = Convert.ToDateTime(reader["tUpdateTime"]); } reader.Close(); } catch (Exception ex) { MessageBox.Show("Check it again" + ex); } } #endregion } } i have already binded the combo box items through designer, When i run the application i just get the reference populated in form 2 and combo box just populated not the particular value which is fetched. New to c# so help me to get familiar

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  • move data from one table to another, postgresql edition

    - by IggShaman
    Hi All, I'd like to move some data from one table to another (with a possibly different schema). Straightforward solution that comes into mind is - start a transaction with serializable isolation level; INSERT INTO dest_table SELECT data FROM orig_table,other-tables WHERE <condition>; DELETE FROM orig_table USING other-tables WHERE <condition>; COMMIT; Now what if the amount of data is rather big, and the <condition> is expensive to compute? In PostgreSQL, a RULE or a stored procedure can be used to delete data on the fly, evaluating condition only once. Which solution is better? Are there other options?

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  • .tpl files and website problem

    - by whitstone86
    Apologies if the title is in lowercase but it's describing an extension format. I've started using Dwoo as my template engine for PHP, and am not sure how to convert my PHP files into .tpl templates. My site is similar to, but not the same as, http://library.digiguide.com/lib/programme/Medium-319648/Drama/ with its design (except colour scheme and site name are different, plus it's in PHP - so copyright issues are avoided here, the design arguably could be seen as parody even though the content is different. The database is called tvguide, and it has these tables: Programmes House M.D. Medium Police Stop! American Dad! The tablenames of the above programmes are: housemdonair mediumonair policestopair americandad1 Episodes The tablenames for the above programmes' episode guides are: housemdepidata mediumepidata policestopepidata americandad1epidata All of them have the following rows: id (not an auto-increment, since I wish to dynamically generate a page from this) episodename seriesnumber episodenumber episodesynopsis (the above four after id do exactly as stated) I have a pagination script that works, it displays 20 records per page as I want it to. This is called pmcPagination.php - but I won't post it in full since it would take up too much space. However, I'm trying to get it so that variables are filled in like this: (ok, so the examples below are ASP.NET, but if there's a PHP/MySQL equivalent I would gratefully appreciate this!!): http://library.digiguide.com/lib/episode/741168 http://library.digiguide.com/lib/episode/714829 with the episode detail and data. My site works, but it's fairly basic, and it's not online yet until my bugs are fixed. Mod_rewrite is enabled so my site reads as http://mytvguide.com/episode/123456 or http://mytvguide.com/programme/123456 http://mytvguide.com/WorldInAction/123456/Documentary/ I've tried looking on Google, but am not sure how to get this TV guide script to work at its best - but I think .tpl, and .php/MySQL is the way to go. Any advice anyone has on making this project into a fully workable, ready to use site would be much appreciated, I've spent months refining this project! P.S. Apologies for the length of this, hope it describes my project well.

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  • I want to do a sql update loop statement, by using the do--while in php

    - by Jean
    Hello, I want to loop the update statement, but it only loops once. Here is the code I am using: do { mysql_select_db($database_ll, $ll); $query_query= "update table set ex='$71[1]' where field='val'"; $query = mysql_query($query_query, $ll) or die(mysql_error()); $row_domain_all = mysql_fetch_assoc($query); } while ($row_query = mysql_fetch_assoc($query)); Thanks Jean

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  • 2-column table with two foreign keys. Performance/design question.

    - by Emanuel
    Hello everyone! I recently ran into a quite complex problem and after looking around a lot I couldn't find a solution to it. I've found answers to my questions many times before on stackoverflow.com, so I decided to post here. So I'm making a user/group managment system for a web-based project, and I'm storing all related data into a postgreSQL database. This system relies on three tables: USERS GROUPS GROUP_USERS The two first tables simply define all the users and all the groups on the site, and the last table, GROUP_USERS, stores the groups every user is part of. It only has two columns: USER_ID GROUP_ID Since every user can be a member of several groups, I decided to make a separate table for this purpose, rather than storing a comma separated column in the USERS-table. Now, both columns are foreign keys, and I want to make them both primary keys as well, this since each combination of USER_ID and GROUP_ID has to be unique, and if I give them the constraint UNIQUE pgAdmin tells me that each table should have at least one Primary key. But now I am stuck with what seems to be a lot of indexes and relations to a very small table only containing numbers. In the end, I want this table to be as fast as possible, even if containing tens of thousands of rows. Size on disk shouldn't be a problem since its just all numbers anyway, but it feels quite stupid to have a full-sized index refering to a smaller table. Should I stick with my current solution, store comma-separated values in a column in the USERS-table or is there any other solution I should be aware of. PS. I don't want to use an array-column, even if they are supported by postgreSQL. I want to be as generic as possible so I can switch database later on, if necessary. EDIT: I other words, will using a compound primary key and two foreign keys in one table with only two columns have a negative impact on performance rather than the opposite due to the size of the generated index? Thank you!

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  • form not showing for empty records

    - by Chris Hodges
    I have a relatively simple PHP page called editcustomers with 3 columns. The problem I'm having is that the form will show when there is a record in the database and the fields will be populated with that info. When no such records exists, the form is not even shown, eliminating the possibility to insert a record. My page layout is as follows: Column 1 shows a form containing customer information, allowing it to be edited. Column 2 allows ordering of products and showing how many products were ordered Column 3 shows the total paid so far, and the total owing. The code for the page I have at present: <html> <?php $id = $_GET['id']; require_once('connect.php'); $sth = $dbh->query("SELECT * FROM users where id = '$id';"); $sth->setFetchMode(PDO::FETCH_ASSOC); $eth = $dbh->query("SELECT * FROM purchases where id = '$id';"); $eth->setFetchMode(PDO::FETCH_ASSOC); ?> <div id="main"> <div id="left"> <form name="custInfo" action ="process.php" method ="post" > <input type = "hidden" name ="formType" value="custInfo"/> <?php while($row = $sth->fetch()){ ?> <p><input type = "hidden" name ="id" value="<?php echo $row["id"] ?>"/> <p><input type = "text" name ="firstName" size ="30" value=" <?php echo $row["firstName"]?>"/> <p><input type = "text" name ="lastName" size ="30" value="<?php echo $row["lastName"]?>"/> <p><input type = "text" name ="country" size ="30" value="<?php echo $row["country"]?>"/> <p></p> <input type="submit" value="Update" /> <?php }?> </div> <div id="mid"> <form name="custCosts" action ="process.php" method ="post" > <input type = "hidden" name ="formType" value="custCosts"/> <?php while($row = $eth->fetch()){ ?> <p><input type = "hidden" name ="id" value="<?php echo $row["id"] ?>"/> <p><input type = "text" name ="amountOwed" size ="30" value=" <?php echo $row["amountOwed"]?>"/> <p><input type = "text" name ="numAaa" size ="30" value="<?php echo $row["numAaa"]?>"/> <p><input type = "text" name ="numBbb" size ="30" value="<?php echo $row["numBbb"]?>"/> <p></p> <input type="submit" value="Update" /> <?php }?> </div> <div id="right"> <b>Total Balance</b> <p> Money owed: </p> <p> aaa total: </p> <p> bbb total: </p> <p> Total: </p> <input type = "text" name ="pay" size ="20" /></p> <input type="submit" value="Make Payment" /> </div> <?php $dbh =null; ?> </body> </html> And the code for all the database trickery: <?php require_once 'connect.php'; $formType = $_POST['formType']; $id = $_POST['id']; $firstName = $_POST['firstName']; $lastName = $_POST['lastName']; $country = $_POST['country']; $amountOwed = $_POST['amountOwed ']; $numAaa = $_POST['numAaa']; $numBbb = $_POST['numBbb']; if(empty($_POST['id'])) { $sth = $dbh->prepare("INSERT INTO customers (firstName, lastName, country) VALUES ('$firstName', '$lastName', '$country')"); $sth->execute(); } elseif(!empty($_POST['id']) && !isset($_POST['stayCost']) && $_POST['formType'] == 'guestInfo'){ $sth = $dbh->prepare("UPDATE customers SET firstName = '$firstName', lastName = '$lastName', country = '$country' WHERE id = '$id'"); $sth->execute(); }elseif(!empty($_POST['id']) && isset($_POST['stayCost']) && $_POST['formType'] == 'guestInfo'){ $sth = $dbh->prepare("INSERT INTO purchases (id, amountOwed, numAaa, numBbb) VALUES ('$id', '$amountOwed', '$numAaa', '$numBbb'"); $sth->execute(); }elseif(!empty($_POST['id']) && $_POST['formType'] == 'guestCosts'){ $sth = $dbh->prepare("UPDATE purchases SET amountOwed= '$amountOwed', numAaa = '$numAaa', numBbb= '$numBbb' WHERE id = '$id'"); $sth->execute(); } $dbh =null; ?> Why does the form not even display if there is no record? An error or something I might understand....but the form is still in the HTML and should still be being output, from what I can see. Why is this not the case?

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