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  • Lua : How to check if one of the values associated with the specified key of a table is nil, from ap

    - by felace
    In lua, it's legal to do this : table={} bar if(table[key]==nil) foo However, using C API, I couldn't find way to check if there's a nil value on the specified position. lua_getglobal(L,"table"); lua_gettable(L,key); If there's a nil value stored in table[key], lua_gettable would give me the "unprotected error in call to Lua API (attempt to index a nil value)" message. Is there any way to check if there's actually something associated with that key, before actually pushing the key to do so ?

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  • Processing a resultset to look up foriegn keys (and poulate a new table!)

    - by Gilly
    Hi, I've been handed a dataset that has some fairly basic table structures with no keys at all. eg {myRubishTable} - Area(varchar),AuthorityName(varchar),StartYear(varchar),StartMonth(varcha),EndYear(varchar),EndMonth(varchar),Amount(Money) there are other tables that use the Area and AuthorityName columns as well as a general use of Month and Years so I I figured a good first step was to pull Area and Authority into their own tables. I now want to process the data in the original table and lookup the key value to put into my new table with foreign keys which looks like this. (lookup Tables) {Area} - id (int, PK), name (varchar(50)) {AuthorityName} - id(int, PK), name(varchar(50) (TargetTable) {myBetterTable} - id (int,PK), area_id(int FK-Area),authority_name_id(int FK-AuthorityName),StartYear (varchar),StartMonth(varchar),EndYear(varchar),EndMonth(varchar),Amount(money) so row one in the old table read MYAREA, MYAUTHORITY,2009,Jan,2010,Feb,10000 and I want to populate the new table with 1,1,1,2009,Jan,2010,Feb,10000 where the first '1' is the primary key and the second two '1's are the ids in the lookup tables. Can anyone point me to the most efficient way of achieving this using just SQL? Thanks in advance Footnote:- I've achieved what I needed with some pretty simple WHERE clauses (I had left a rogue tablename in the FROM which was throwing me :o( ) but would be interested to know if this is the most efficient. ie SELECT [area].[area_id], [authority].[authority_name_id], [myRubishTable].[StartYear], [myRubishTable].[StartMonth], [myRubishTable].[EndYear], [myRubishTable].[EndMonth], [myRubishTable].[Amount] FROM [myRubishTable],[Area],[AuthorityName] WHERE [myRubishTable].[Area]=[Area].[name] AND [myRubishTable].[Authority Name]=[dim_AuthorityName].[name] TIA

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  • How can I get the contents of my table with dynamic row adding?

    - by user359706
    how to retrieve from the server-side contained a table html constructed this way: <table id="myTable"> <tr> <th> <input type="text"> name </th> <th> <input type="text"> quantity </th> </tr> <tr> <th> <input id="name_1"> phone </th> <th> <input id="quantity_1"> 15 </th> </tr> <tr> <th> <input ="name_2"> id mp3 </th> <th> <input id="quantity_2"> 26 <</th> </tr> ... I can not make use of <asp:Table> ... because for technical reasons I did not find a solution following this post: http://stackoverflow.com/questions/3003912/how-to-dynamic-adding-rows-into-asp-net-table How can retrieve the contents values of my table (dynamic) for each row. Rows will be added in client-side js Thank you.

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  • Java ME Runnable object takes up memory although not made an instance yet

    - by user1646684
    I am facing a strange problem with memory in Java ME. here is a part of my code: int variable=1; while (true) { if (variable==2) { display = Display.getDisplay(this); MyCanvas mc = new MyCanvas(this); // MyCanvas is a runnable object mcT = new Thread(mc); // new thread for MyCanvas mc.repaint(); display.setCurrent(mc); mcT.start(); // run thread } if (variable==1) { // Do some other stuff } } The problem is that although still the variable is set to 1, so it does not come through the if (variable==2) condition the program consumes 300kB more memory than when I delete the code after condition if (variable==2). As far as I know the code should by executed and the objects shall be created only when I set variable to value 2. But it consumes the memory also when the code after condition "if (variable==2)" is not executed. Why does this happen?

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  • Update table instantly or “Bulk” Update in database later? And is it advisable?

    - by Mestika
    Hi, I have a question regarding a semi-constant update in a database. In short it is regarding a checkout function on a web page, which each time the checkout function is evoked it do five steps. I want to try to optimize this function and have my eye on a step where I update a table each time the checkout is performed. I take the information retrieved from the shopping cart and then update the table in question. I do have some indexes on the table, the gain from those are greater than leaving them so this is a cost I’m willing to take. Now, my question is. Could it in some way regarding to performance be better to not update the table instantly but collect every checkout items and save them in some way (maybe in a file) and then at a specific time (or several times) at day take this file and then update the table with the new information. Then I started thinking about if there was a possibility to use some sort of Bulk Update to take a file, hashmap, array (or?) and then update it. And I’m using IBM DB2 version 9.7 Mestika

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  • How do I overflow text to the left in a table?

    - by remack
    I have a table with fixed layout. On overflow, the contents of cells should clip from the left instead of the right. That is, if the width of the TD is less than the width of the text, the cell below should display "67890" instead of "12345". This needs to work in IE7+ at minimum. Is there a way to do this in css without any JavaScript? <table style="table-layout:fixed"> <tr> <TD> 12334567890 </TD> </tr> </table>

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  • In Android, does _id have to be present in any table created?

    - by Andy
    I am trying to create a table to only has a foreign key, not a primary key. I am getting this error: java.lang.IllegalArgumentException: column '_id' does not exist I read a tutorial that the primary key must be _id, with no explanation. And that is fine. But what if I do not want a primary key! What if I only want a foreign key. I am assuming this is where my problem lies. The schemas below are what I have. But the third one is where I assume this is coming from. database.execSQL("CREATE TABLE events (" + "_id INTEGER PRIMARY KEY, event_name TEXT" + ")"); database.execSQL("CREATE TABLE reminders(_id INTEGER PRIMARY KEY, event_name TEXT" + ")"); database.execSQL("CREATE TABLE events_info (_id INTEGER, event_name TEXT, all_day INTEGER, " + "start_date INTEGER, start_time INTEGER, end_date INTEGER, end_time INTEGER," + " location TEXT, reminder_id INTEGER, notes TEXT, repeat TEXT," + "FOREIGN KEY(_id) REFERENCES events(_id), FOREIGN KEY(reminder_id) REFERENCES reminders(_id))" );

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  • How to make a staging table in ms sql 2005?

    - by chobo2
    Hi I heard about doing staging tables and I am wondering how you actually do it. I want to do a sqlbulk copy into a staging table. Then then update the real table. I heard in mssql 2008 that you can use something called merge but I am using ms sql 2005 so I heard I have to use a update inner join? I am not sure how that would look like(I am guessing best way would be to write it in SP). Also the staging table needs to be able to handle concurrent updates. I was thinking of putting another column in the staged as GUID so that way I know which records belong to which group and when it is time to delete the records from the staged table I can just use that. So can anyone show me any examples or tutorials on how to do it? Also how fast is this way? Say if your updating 50,000 records how long would that take(a guesstimate is fine)

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  • Please explain this delete top 100 SQL syntax

    - by Patrick
    Basically I want to do this: delete top( 100 ) from table order by id asc but MS SQL doesn't allow order in this position The common solution seems to be this: DELETE table WHERE id IN(SELECT TOP (100) id FROM table ORDER BY id asc) But I also found this method here: delete table from (select top (100) * from table order by id asc) table which has a much better estimated execution plan (74:26). Unfortunately I don't really understand the syntax, please can some one explain it to me? Always interested in any other methods to achieve the same result as well. EDIT: I'm still not getting it I'm afraid, I want to be able to read the query as I read the first two which are practically English. The above queries to me are: delete the top 100 records from table, with the records ordered by id ascending delete the top 100 records from table where id is anyone of (this lot of ids) delete table from (this lot of records) table I can't change the third one into a logical English sentence... I guess what I'm trying to get at is how does this turn into "delete from table (this lot of records)". The 'from' seems to be in an illogical position and the second mention of 'table' is logically superfluous (to me).

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  • how do i use @var on a function variable?

    - by fayer
    i've got a variable $user that is of data type User (a class). i've got it in a class method so i can't just type: /** * @var User */ $user = Factory::getInstance('User'); because that will work only with class properties, not method variables like in this case. how could i tell netbeans that that variable is of data type User in a method? Thanks!

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  • How to design a database where the main entity table has 25+ columns but a single entity's columns g

    - by thenextwebguy
    The entities to be stored have 25+ properties (table columns). The entities are pretty diverse, meaning that, most of the columns are empty. On average, I'd say, less than 20% (<5) properties have a value in any particular item. So, I have a lot of redundant empty columns for most of the table rows. Almost all of the columns are decimal numbers. Given this scenario, would you suggest serializing the columns instead, or perhaps, create another table named "Property", which would contain all the possible properties and then creating yet another table "EntityProperty" which would map an property to an entity using foreign keys? Or would you leave it as it is?

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  • In Windows Vista and 7, I can't access the %DEFAULTUSERPROFILE% system variable - it shows as not fo

    - by shifuimam
    If I try to access this system variable from the Run... dialog, Windows tells me the directory doesn't exist. Some system variables, like %SYSTEMROOT% and %USERPROFILE%, do work. Consequently, if I try to use a supposedly nonexistent variable like %DEFAULTUSERPROFILE% or %PROFILESFOLDER% in C#, I get nothing in return. Is there something special I need to do to get access to these variables?

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  • MySQL – Introduction to User Defined Variables

    - by Pinal Dave
    MySQL supports user defined variables to have some data that can be used later part of your query. You can save a value to a variable using a SELECT statement and later you can access its value. Unlike other RDBMSs, you do not need to declare the data type for a variable. The data type is automatically assumed when you assign a value. A value can be assigned to a variable using a SET command as shown below SET @server_type:='MySQL'; When you above command is executed, the value, MySQL is assigned to the variable called @server_type. Now you can use this variable in the later part of the code. Suppose if you want to display the value, you can use SELECT statement. SELECT @server_type; The result is MySQL. Once the value is assigned it remains for the entire session until changed by the later statements. So unlike SQL Server, you do not need to have this as part the execution code every time. (Because in SQL Server, the variables are execution scoped and dropped after the execution). You can give column name as below SELECT @server_type AS server_type; You can also SELECT statement to DECLARE and SELECT the values for a variable. SELECT @message:='Welcome to MySQL' AS MESSAGE; The result is Message -------- Welcome to MySQL You can make use of variables to effectively apply many logics. One of the useful method is to generate the row number as shown in this post MySQL – Generating Row Number for Each Row using Variable. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Tips and Tricks, T SQL

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