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  • how can i set up a uniqueness constraint in mysql for columns that can be null?

    - by user299689
    I know that in MySQL, UNIQUE constraits don't treat NULL values as equal. So if I have a unique constraint on ColumnX, then two separate rows can have values of NULL for ColumnX and this wouldn't violate the constraint. How can I work around this? I can't just set the value to an arbitrary constant that I can flag, because ColumnX in my case is actually a foreign key to another table. What are my options here? Please note that this table also has an "id" column that is its primary key. Since I'm using Ruby on Rails, it's important to keep this id column as the primary key. Note 2: In reality, my unique key encompasses many columns, and some of them have to be null, because they are foreign keys, and only one of them should be non-null. What I'm actually trying to do is to "simulate" a polymorphic relationship in a way that keep referential integrity in the db, but using the technique outlined in the first part of the question asked here: http://stackoverflow.com/questions/922184/why-can-you-not-have-a-foreign-key-in-a-polymorphic-association

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  • JOIN (SELECT DISTINCT [..] substitute

    - by FRKT
    Hello, I'd like to find a substitute for using SELECT DISTINCT in a derived table. Let's say I have three tables: CREATE TABLE `trades` ( `tradeID` int(11) unsigned NOT NULL AUTO_INCREMENT, `employeeID` int(11) unsigned NOT NULL, `corporationID` int(11) unsigned NOT NULL, `profit` int(11) NOT NULL, KEY `tradeID` (`tradeID`), KEY `employeeID` (`employeeID`), KEY `corporationID` (`corporationID`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 CREATE TABLE `corporations` ( `corporationID` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL, PRIMARY KEY (`corporationID`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 CREATE TABLE `employees` ( `employeeID` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL, PRIMARY KEY (`employeeID`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 Let's say I'd like to find out how much profit a specific employee has generated. Simple: SELECT SUM(profit) FROM trades JOIN employees ON trades.employeeID = employees.employeeID AND employees.employeeID = 1; It gets trickier if I'd like to query how much revenue a specific corporation has, however. I cannot simply replicate the aforementioned query, because two or more employees from the same company might be involved in the same trade. This query should do the trick: SELECT SUM(profit) FROM trades JOIN (SELECT DISTINCT tradeID FROM trades WHERE trades.corporationID = 1) ... unfortunately, DISTINCT JOINs seem crazy ineffective. Is there any alternative I can use to determine how much revenue a corporation has, taking into account that a corporation might be listed several times with the same tradeID?

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  • Using - Instead of + in WordPress Search Permalink

    - by poer
    Options +FollowSymLinks RewriteEngine On RewriteCond %{THE_REQUEST} ^[A-Z]+ /(#[^?& ]*)??([^& ]*&)?s=([^& ]+)[^ ]* HTTP/ RewriteRule ^$ http://wordpressblog.com/search/%3? [R=301,L] Currently I use the above .htaccess mod_rewrite rule to convert default WordPress search permalink: http://wordpressblog.com/?s=key+word into nice permalink like this: http://wordpressblog.com/search/key+word My question is: What part of the mod_rewrite rule above that I need to change to get a nicer permalink like this one: http://wordpressblog.com/search/key-word.html Thanks.

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  • Modulus PHP Problem

    - by Eli
    I have a problem, I am trying to calculate what the lowest prime is of a number but I do not understand the result that PHP is giving me. If I have this number $number = 600851475143; Then I modulus it: $primes = array( 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97); foreach($primes as $key=>$value) { if($number % $value == 0 ) {echo $value; break; } } Why is it that $value = 3? If $value = 3, that means that 600851475143 / 3 should be an integer, but its not. So I do not understand why that if() evaluates to true?

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  • How to Detect an Event Coming from the Firefox History Dropdown Box

    - by banterCZ
    How to detect an event coming from the Firefox history dropdown box? I need to distinguish between the enter key simply pressed on input field or on item from his native history dropdown box. The reason is that I would like to call custom submit button (not first one, which is default) on the enter key pressed on any input field. But right now, the enter key pressed on history dropdown box unfortunately call submit as well.

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  • Verify p2p node

    - by mazzzzz
    Hey guys, I have been working on a p2p namespace for some of my programs. I created a system to encrypt/decrypt the packets send/received with the class. I was using the basic public private key system: 1) encrypt the data with Symmetric encryption 2) encrypt the symmetric key with RSA. Then do the opposite when you decrypted.. I was wondering though, how would you verify if the packet was coming from where it said it was. I was going to use a basic certificate system (where you encrypt with your private RSA key, then they decrypt it with your public key), but I don't know how to do this with C#. I am using the RSACryptoServiceProvider class. Does anyone know how do this? Thanks, Max

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  • OpenSSL compatible API for Scala?

    - by pfleidi
    Hello, I'm working on a project with a friend. He's implementing his software in Ruby and I'm doing my stuff in Scala (with Lift). We're using some asynchronous encryption and he is using the ruby OpenSSL bindings for that: key = OpenSSL::PKey::RSA.generate(4096) self.public_key = key.public_key self.private_key = key What I'm looking for is a simple API which is compatible to OpenSSL and runs on the JVM. I need it to create key-pairs and to encrypt and sign our payload. Do you have any suggestions?

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  • Are C++ Reads and Writes of an int atomic

    - by theschmitzer
    I have two threads, one updating an int and one reading it. This value is a statistic where the order of the read and write is irrelevant. My question is, do I need to synchronize access to this multi-byte value anyway? Or, put another way, can part of the write be complete and get interrupted, and then the read happen. For example, think of value = ox0000FFFF increment value to 0x00010000 Is there a time where the value looks like 0x0001FFFF that I should be worried about? Certainly the larger the type, the more possible something like this is I've always synchronized these types of accesses, but was curious what the community thought.

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  • Foreign Keys and Primary Keys at the same time

    - by Bader
    hello , i am trying to create table (orderdetails) , the table has two FKs and PKs at the same keys here is my code create table OrderDetails2 ( PFOrder_ID Number(3) PFProduct_ID Number(3) CONSTRAINT PF PRIMARY KEY (PFOrder_ID,PFProduct_ID), CONSTRAINT FK_1 FOREIGN KEY (PFProudct_ID) REFERENCES Product(Product_ID), CONSTRAINT FK_2 FOREIGN KEY (PFOrder_ID) REFERENCES Orderr(Order_ID) ); i am using Oracle express , a problem pops when i run the code , here is it ORA-00907: missing right parenthesis what is the problem ?

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  • Localizing a plist with grouped data

    - by Robert Altman
    Is there a way to localize a plist that contain hierarchical or grouped data? For instance, if the plist contains: Book 1 (dictionary) Key (string) Name (string) Description (localizable string) Book 2 (dictionary) Key (string) Name (string) Description (localizable string) (etcetera...) For the sake of the example, the Key and Name should not be translated (and preferably should not be duplicated in multiple localized property lists). Is there a mechanism for providing localizations for the localizable Description field without localizing the entire property list? The only other strategy that came to my mind is to store a lookup key in the description field and than use that to retrieve the localized text via NSLocalizedString(...) Thanks.

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  • Using sscanf to parse two strings out

    - by Jessica
    I have a semi xml formatted file that contains line with the following format: <param name="Distance" value="1000Km" /> The first char in the string is usually a TAB or spaces. I've been using the following to try to parse the two strings out (from name and value): if(sscanf(lineread, "\t<param name=\"%s\" value=\"%s\" />", name, value) == 1) { //do something } name and value are char* Now, the result is always the same: name gets parse (I need to remove the quotes) and name is always empty. What am I doing wrong? Thanks, code is appreciated. Jess.

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  • how to copy char * into a string and vice-versa

    - by user295030
    If i pass a char * into a function. I want to then take that char * convert it to a std::string and once I get my result convert it back to char * from a std::string to show the result. I don't know how to do this for conversion ( I am not talking const char * but just char *) I am not sure how to manipulate the value of the pointer I send in. so steps i need to do take in a char * convert it into a string. take the result of that string and put it back in the form of a char * return the result such that the value should be available outside the function and not get destroyed. If possible can i see how it could be done via reference vs a pointer (whose address I pass in by value however I can still modify the value that pointer is pointing to. so even though the copy of the pointer address in the function gets destroyed i still see the changed value outside. thanks!

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  • Why is JSON outputting out of order?

    - by dcp3450
    I'm am trying to get a list of weather information for 8 locations. I'm using a weather API that accepts longitude and latitude and spits back json output with the weather info for that location. I feed the coords in order 0-7 but when json processes the data it comes back in a seemingly random order. I assume it's because some process faster than others and json is outputing what it gets back as it gets it. The output is correct, only the order is wrong. var loc = null; var body = ""; var campuses = new Array(8); campuses[0] = "34.47242,-84.42489,1"; campuses[1] = "33.81488,-84.62048,2"; campuses[2] = "34.27502,-84.46976,3"; campuses[3] = "33.92987,-84.55065,4"; campuses[4] = "34.03433,-84.46723,5"; campuses[5] = "34.08362,-84.67115,6"; campuses[6] = "33.91124,-84.82634,7"; campuses[7] = "34.10409,-84.51804,8"; function getWeather(campusArray) { body += '<p class="topTitle">Campus Weather</p>'; var cSplit = new Array(); cSplit = campusArray.split(','); var loc = "http://www.worldweatheronline.com/feed/weather.ashx?q="+cSplit[0]+","+cSplit[1]+"&format=json&num_of_days=2&key=0a05fff921162948110401&callback=?"; $('#content').html('asdf'); $.getJSON(loc,function(js) { var data = js.data; var humidity = data.current_condition[0].humidity; var tempF = data.current_condition[0].temp_F; var iconDESC = data.current_condition[0].weatherDesc[0].value; var iconURL = data.current_condition[0].weatherIconUrl[0].value; var windDir = data.current_condition[0].winddir16Point; var windSpeed = data.current_condition[0].windspeedMiles; var tempMaxF = data.weather[0].tempMaxF; var tempMinF = data.weather[0].tempMinF; body += '<p class="title">'+cSplit[2]+'</p>'+ '<span class="body">'+tempF+ ' '+windSpeed+ '<img src="'+iconURL+'" /></span>'; $('#content').html(body); }); } getWeather(campuses[0]); getWeather(campuses[1]); getWeather(campuses[2]); getWeather(campuses[3]); getWeather(campuses[4]); getWeather(campuses[5]); getWeather(campuses[6]); getWeather(campuses[7]); I have also tried it as $.ajax var loc = null; var body = ""; var campuses = new Array(8); campuses[0] = "34.47242,-84.42489,1"; campuses[1] = "33.81488,-84.62048,2"; campuses[2] = "34.27502,-84.46976,3"; campuses[3] = "33.92987,-84.55065,4"; campuses[4] = "34.03433,-84.46723,5"; campuses[5] = "34.08362,-84.67115,6"; campuses[6] = "33.91124,-84.82634,7"; campuses[7] = "34.10409,-84.51804,8"; function getWeather(campusArray) { body += '<p class="topTitle">Campus Weather</p>'; var cSplit = new Array(); cSplit = campusArray.split(','); var loc = "http://www.worldweatheronline.com/feed/weather.ashx?q="+cSplit[0]+","+cSplit[1]+"&format=json&num_of_days=2&key=0a05fff921162948110401&callback=?"; $.ajax({ url: loc, async: true, dataType: "json", success: function(js) { var data = js.data; var humidity = data.current_condition[0].humidity; var tempF = data.current_condition[0].temp_F; var iconDESC = data.current_condition[0].weatherDesc[0].value; var iconURL = data.current_condition[0].weatherIconUrl[0].value; var windDir = data.current_condition[0].winddir16Point; var windSpeed = data.current_condition[0].windspeedMiles; var tempMaxF = data.weather[0].tempMaxF; var tempMinF = data.weather[0].tempMinF; body += '<p class="title">'+cSplit[2]+'</p>'+ '<span class="body">'+tempF+ ' '+windSpeed+ '<img src="'+iconURL+'" /></span>'; $('#content').html(body); } }); } getWeather(campuses[0]); getWeather(campuses[1]); getWeather(campuses[2]); getWeather(campuses[3]); getWeather(campuses[4]); getWeather(campuses[5]); getWeather(campuses[6]); getWeather(campuses[7]); EDIT: example of json output: { "data": { "current_condition": [ {"cloudcover": "100", "humidity": "93", "observation_time": "04:04 PM", "precipMM": "0.0", "pressure": "1009", "temp_C": "2", "temp_F": "36", "visibility": "8", "weatherCode": "116", "weatherDesc": [ {"value": "Mist" } ], "weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0006_mist.png" } ], "winddir16Point": "WNW", "winddirDegree": "290", "windspeedKmph": "7", "windspeedMiles": "4" } ], "request": [ {"query": "Lat 34.47 and Lon -84.42", "type": "LatLon" } ], "weather": [ {"date": "2011-01-06", "precipMM": "9.3", "tempMaxC": "7", "tempMaxF": "45", "tempMinC": "2", "tempMinF": "35", "weatherCode": "113", "weatherDesc": [ {"value": "Sunny" } ], "weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0001_sunny.png" } ], "winddir16Point": "WNW", "winddirDegree": "293", "winddirection": "WNW", "windspeedKmph": "20", "windspeedMiles": "13" }, {"date": "2011-01-07", "precipMM": "0.0", "tempMaxC": "6", "tempMaxF": "44", "tempMinC": "0", "tempMinF": "31", "weatherCode": "116", "weatherDesc": [ {"value": "Partly Cloudy" } ], "weatherIconUrl": [ {"value": "http:\/\/www.worldweatheronline.com\/images\/wsymbols01_png_64\/wsymbol_0002_sunny_intervals.png" } ], "winddir16Point": "WNW", "winddirDegree": "286", "winddirection": "WNW", "windspeedKmph": "25", "windspeedMiles": "16" } ] }}

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  • Spring MVC JSP Parameters

    - by zpinter
    I'm looking to turn off try blocks for a specific JSP page (though turning it off globally would be OK as well). From what I've gathered, it looks something like this: <jsp-param> <param-name>noTryBlocks</param-name> <param-value>true</param-value> </jsp-param> However, everywhere I see that sample it's for a weblogic.xml file. Does anybody know how I can set this JSP parameters for a Spring MVC application? web.xml? Perhaps somewhere near here?: <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/> <property name="prefix" value="/WEB-INF/jsp/"/> <property name="suffix" value=".jsp"/> </bean>

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  • REST authentication S3 like hmac sha1 signature vs symetric data encryption.

    - by coulix
    Hello stackers, I was arguing about an S3 like aproach using authorization hash with a secret key as the seed and some data on the request as the message signed with hmac sha1 (Amazon S3 way) vs an other developer supporting symetric encryption of the data with a secret key known by the emiter and the server. What are the advantage of using signed data with hmac sha1 vs symetric key other than the fact that with the former, we do not need to encrypt the username or password. What would be the hardest to break ? symetric encryption or sha1 hashing at la S3 ? If all big players are using oauth and similar without symetric key it is sure that there are obvious advantages, what are those ?

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  • Right way to access the Google Cloud Storage bucket via Public API

    - by SyBer
    I'm trying the following request to access the bucket by using curl, via the public API: curl -X POST -H 'Content-Type: image/jpeg' -d @xxx.jpeg 'https://www.googleapis.com/upload/storage/v1/b/clips.eyecam.com/o?uploadType=media&name=x.jpeg&key=XXX' With XXX being the generated key in the Public API. However I'm getting an authorization failure: { "error": { "errors": [ { "domain": "global", "reason": "required", "message": "Login Required", "locationType": "header", "location": "Authorization" } ], "code": 401, "message": "Login Required" } } Seems the request is incorrect and does not pass the authorization key, any idea what would be the right form of the request?

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  • Quantity in amazon cart?

    - by user201140
    Hi I'd like to change the quantity in an AWS order. I've used the form below and that works fine for adding 1 item to the cart, but when I try to change it to a quantity of 2 it says there are no items in my cart. What am I doing wrong? Thanks. <form method="GET" action="http://www.amazon.com/gp/aws/cart/add.html" id="Quantity"> <input type="hidden" name="AWSAccessKeyId" value="Access Key ID" /> <input type="hidden" name="AssociateTag" value="Associate Tag" /> <?php echo "<input type='hidden' name='ASIN.1' value='".$itemid."'/>"; ?> <input type="hidden" name="Quantity.1" value="1"/><br/> <input type="image" src="buynow.gif" value="Submit" alt="Submit"> </form>

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  • PHP Magic methods not working

    - by user991047
    I am trying to create a registry class with magic __set and __get my class looks like class Registry { private $vars = array(); public function __set($key, $value) { $this->vars[$key] = $value; dump($key, $value); } public function __get($index) { $this->vars[$index]; } } but if i try to save some variable in registry class in gets only the $key the $value is alway NULL. here is the sample code how I am try to call this class $registry = new registry; $registry->router = $router; $registry->title = "Welcome ";

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  • Please help me in creating an update query

    - by Rajesh Rolen- DotNet Developer
    I have got a table which contains 5 column and query requirements: update row no 8 (or id=8) set its column 2, column 3's value from id 9th column 2, column 3 value. means all value of column 2, 3 should be shifted to column 2, 3 of upper row (start from row no 8) and value of last row's 2, 3 will be null For example, with just 3 rows, the first row is untouched, the second to N-1th rows are shifted once, and the Nth row has nulls. id math science sst hindi english 1 11 12 13 14 15 2 21 22 23 24 25 3 31 32 33 34 35 The result of query of id=2 should be: id math science sst hindi english 1 11 12 13 14 15 2 31 32 23 24 25 //value of 3rd row (col 2,3) shifted to row 2 3 null null 33 34 35 This process should run for all rows whose id 2 Please help me to create this update query I am using MS sqlserver 2005

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  • Entity Framework one-to-one relationship mapping flattened in code

    - by Josh Close
    I have a table structure like so. Address: AddressId int not null primary key identity ...more columns AddressContinental: AddressId int not null primary key identity foreign key to pk of Address County State AddressInternational: AddressId int not null primary key identity foreign key to pk of Address ProvinceRegion I don't have control over schema, this is just the way it is. Now, what I want to do is have a single Address object. public class Address { public int AddressId { get; set; } public County County { get; set; } public State State { get; set } public ProvinceRegion { get; set; } } I want to have EF pull it out of the database as a single entity. When saving, I want to save the single entity and have EF know to split it into the three tables. How would I map this in EF 4.1 Code First? I've been searching around and haven't found anything that meets my case yet. UPDATE An address record will have a record in Address and one in either AddressContinental or AddressInternational, but not both.

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  • How do i translate this to "simpler" JavaScript?

    - by Julian Weimer
    Since i'm working with Titanium i realzed that its current JavaScript Interpreter doesn't accept specific coding-styles. So for for-loops and if-statements i have to have braces, even though i only want to span one line. Furthermore there is more i have to change if i want to use a Javascript Library like underscore.js. This is what Titanium doesn't want to see: if (!(result = result && iterator.call(context, value, index, list))) {_.breakLoop();} if (nativeSome && obj.some === nativeSome) {return obj.some(iterator, context);} var computed = iterator ? iterator.call(context, value, index, list) : value; computed >= result.computed && (result = {value : value, computed : computed}); Can i use a simpler syntax to describe the logic behind those lines of code?

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  • Parameter attributes in c#

    - by ng
    How can I do the following with c# attributes. Below is a snippet of Java that annotates parameters in a constructor. public class Factory { private final String name; private final String value; public Factory(@Inject("name") String name, @Inject("value") String value) { this.name = name; this.value = value; } } From looking at c# annotations it does not look like I can annotate parameters. Is this possible?

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  • How to unregister a specific hotkey using c#

    - by srk
    I am using the below code to register a HotKey : RegisterGlobalHotKey(Keys.F4, USE_ALT); private void RegisterGlobalHotKey(Keys hotkey, int modifiers) { try { // increment the hot key value - we are just identifying // them with a sequential number since we have multiples mHotKeyId++; if (mHotKeyId > 0) { // register the hot key combination if (RegisterHotKey(this.Handle, mHotKeyId, modifiers, Convert.ToInt16(hotkey)) == 0) { // tell the user which combination failed to register - // this is useful to you, not an end user; the end user // should never see this application run MessageBox.Show("Error: " + mHotKeyId.ToString() + " - " + Marshal.GetLastWin32Error().ToString(), "Hot Key Registration"); } } } catch { // clean up if hotkey registration failed - // nothing works if it fails UnregisterGlobalHotKey(); } } private void UnregisterGlobalHotKey() { // loop through each hotkey id and // disable it for (int i = 0; i < mHotKeyId; i++) { UnregisterHotKey(this.Handle, i); } } How can i unregister the Hot key and Make Alt+ F4 keep working again ?

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  • MySQL query problem

    - by Luke
    Ok, I have the following problem. I have two InnoDB tables: 'places' and 'events'. One place can have many events, but event can be created without entering place. In this case event's foreign key is NULL. Simplified structure of the tables looks as follows: CREATE TABLE IF NOT EXISTS `events` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, `places_id` int(9) unsigned DEFAULT NULL, PRIMARY KEY (`id`), KEY `fk_events_places` (`places_id`), ) ENGINE=InnoDB; ALTER TABLE `events` ADD CONSTRAINT `events_ibfk_1` FOREIGN KEY (`places_id`) REFERENCES `places` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION; CREATE TABLE IF NOT EXISTS `places` ( `id` int(9) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, PRIMARY KEY (`id`), ) ENGINE=InnoDB; Question is, how to construct query which contains name of the event and name of the corresponding place (or no value, in case there is no place assigned?). I am able to do it with two queries, but then I am visibly separating events which have place assigned from the ones that are without place. Help really appreciated.

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  • Right design to validate attributes of a class instance

    - by systempuntoout
    Having a simple Python class like this: class Spam(object): __init__(self, description, value): self.description = description self.value = value Which is the correct approach to check these constraints: "description cannot be empty" "value must be greater than zero" Should i: 1.validate data before creating spam object ? 2.check data on __init__ method ? 3.create an is_valid method on Spam class and call it with spam.isValid() ? 4.create an is_valid static method on Spam class and call it with Spam.isValid(description, value) ? 5.check data on setters? 6.... Could you recommend a well designed\Pythonic\not verbose (on class with many attributes)\elegant approach?

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