Let's say I have a database which has the names of all the ships.
If I wish to select all the ships which have minimum of 10 guns, I'd do.
SELECT Class AS Class,Country.
FROM Classes
WHERE numGuns >=10;
However, I wish to select all ships and print them out who have numGuns >= 10, I've tried googling myself out of this however I haven't found something simple to work with and work from there.
Any help is appreciated.
This is just to get the question out of the list of unanswered questions
(and close-voting did not help).
The problem is caused by the simple mistake of trying to list the ship attributes "class" and "country", according to the attribute "numGuns" from a class table (which at least does not have all of these attributes) instead of from a ship table (where they exist).
Related
I have a table called Items with a column called Name. How can I do a query to get only items that start with a certain letter?
For example if I wanted all items that start with words R2. I tried the code below but its wrong :
Future<List<Item>> getFilteredItems() => (select(items)..where((t) => t.Name.like('R2'))).get();
What is the proper to write the query?
All aspects of your questions beyond simple SQLite are beyond my knowledge.
But turns out (confirmed by OP) that my first doubt solved the problem:
Use 'R2%' instead of 'R2'. I.e. use the proper SQLite wildcard.
I'm new to programming, so bear with me as I try to explain what I"m needing to do. This is in ASP.net iwth VB. I have a quiz project that I've been assigned for work. This quiz project contains two main SQL Databases it pulls the info from.
First is a Quiz table, which contains three columns: QuizID (Pri Key), Title, Description. This is where I declare the quizzes, indicated by the QuizID (1, 2, 3....etc)
The second table is the Questions table, containing the following columns: QuestionsID (Pri Key), Title, Answer1, Answer2, Answer3, Answer4, Answer5, CorrectAnswer, QuestionOrder, QuizID
The QuizID in the Quesitons table matches the QuizID in the Quiz table. Thus for QuizID = 1, it consists of all the questions with the matching QuizID in the Questions table. The CorrectAnswer I want to assign a simple value (1, 2, 3...etc).
I need a way to take a set of questions (based on the QuizID) put them in some sort of table and randomize them (or rather shuffle them) so that each time this quiz is taken, it pulls all questions randomly, but not repeating any)
I then want the code to pull the question and coorepsonding answers to pick from in a radiobuttonlist. However, It only needs to pull the number of answers. Example, a True/False will only have Answer1 and Answer2. The other Answers will have the NULL value in it.
There needs to then be a way to go through each one of these questions that have been placed in the table (in that random order) using a "next" button. When a question and possible answwers are displayed, I alaready have code to keep the answers in the session to grade it at the end (using correctAnswer and selected answer.
I have no specific way to bind the data to the Database. I have used SQLDataSource to make other connections before, but I don't know if this is the best way.
Thanks in advance for any advice. As I said, I'm a noob, so providing all the code will be helpful.
Can you provide any sample code to demonstrate the approach that you wish to take. I am willing to help you learn and fix bugs, but I wont write all your code for you.
It is easy to calculate a sum, an average or a maximum accross set of fields using built-in xpath functions.
But is it possible to calculate a product?
Assuming I have repeating elements like
<my:table>
<my:row>
<my:value>10</my:value>
</my:row>
<my:row>
<my:value>20</my:value>
</my:row>
<my:row>
<my:value>30</my:value>
<my:row>
</my:table>
(the number of my:rows may vary).
i need to have a formula multiplying all my:values: 10*20*30 (and working with any number of rows).
Any ideas?
Please do not suggest code solutions, I need this for a restricted form.
Using conditional hack described here, I finally assembled the solution.
Inside my:row, create a running product field my:valueCumul, populated using a formula to refer to previous row, and leveraging the conditional hack to override NaN for the first row:
../my:value *
concat(
(count(../preceding-sibling::my:row[1]) = 0) * 1,
substring(../preceding-sibling::my:row[1]/my:valueCumul, 1, (count(../preceding-sibling::my:row[1]) = 1) * string-length(../preceding-sibling::my:row[1]/my:valueCumul))
)
Outside the table you can easily refer to my:valueCumul in the last row to get total product:
../my:row[count(../my:row)]/my:valueCumul
The nice features of this solution are:
Works in a browser form in any sharepoint environment
Is not impacted by "16 calculations" threshold
The formula is robust to row removal and shifts
You can't with the built in functions in InfoPath.
However, don't write off a code solution so fast. If you only access data elements in the form itself (nothing EXTERNAL) then you can leave the form as restricted security and the code will run with no problems - the user doesn't know the difference.
It is fairly trivial to attach to the right event, grab the nodes, and loop through them while multiplying. You don't even have to use managed code - use one of the script options. Comment back (or update your original post) if you run into any troubles and we can help resolve them.
I'm using the Feeds module to import lots of Feed Item nodes. Due to a malformed feed file, I'm getting lots of duplicates. I'm using a View to display these nodes, and need to be able to add a DISTINCT filter on the "Node: Post Date" field, so I only get 1 result for each post-date.
I will also look into tackling the problem at the source so to speak (I don't want to have all those duplicates in the first place), but this is an interesting issue in itself - I can't find a way to add a DISTINCT filter on a field other than the Node ID (which has it's own option in the View's Basic Settings box).
I found a great article on a good way to alter the SQL queries that are generated from views before they get executed: http://echodittolabs.org/blog/2010/06/group-views. I used this to basically suffix a GROUP BY clause to the end of the query (in a really nice, clean and versatile way).
As an aside, I also found a way to tackle the issue of importing lots of duplicate feed items, the details of which are here: http://drupal.org/node/661314#comment-3667228. It adopts quite an extreme approach (deleting all items before each update), but this is the only solution for some nasty malformed feeds.
I was holding out for some undiscovered feature of Views that let you do this, but I don't think there is one - maybe in the next version ;)
There are two option to solve this:\
apply this patch
OR
hook_views_query_alter => just paste
$query->distinct = 1;
$query->no_distinct = 'views_groupby';
I guess you have two options: either put some logic in the view template file to skip the duplicate items or implement hook_views_query_alter() to change the query used by the view, adding the DISTINCT clause.
We found this issue in drupal 6.x view - had 7 of 150 items duplicated one or twice. No idea why. Issue only appeared for anonymous users. Luckily, views 6.x.2.16 provides a 'distinct' setting under the basic settings, I set it to Yes and got rid of the duplicates.
I'm using Drupal's Views 2, and need to retrieve min values from fields in a custom table. The query for this is easy if I were writing it by hand--something like, "SELECT foo, min(bar) FROM table GROUP BY foo." But how would I do this using Views? I've already defined the table in a views.info file, so there's no trouble getting views to see the table. It's the Min() part of the query I just don't understand. My next stop will be the Views API documentation, but if someone can just provide the outline for how to do this quickly, I would greatly appreciate it.
New answer to an old question, but something like this will work. You need to create a custom field handler and then wrap the field as follows:
class views_handler_custom_field extends views_handler_field {
function query() {
$this->ensure_my_table();
$this->field_alias = $this->query->add_field("MAX({$this->table_alias}", "{$this->real_field})",$this->table_alias . "_" . $this->real_field);
}
}
Use aggregation from advanced configuration of views. After this is set
yes you can select max, min or any other selector to fields.
Test your results but it should work well
Alternatively in some cases you can sort your data ascending or
descending and then just pick one to be shown on the view. Can be
problematic when displaying multiple fields or so.
After testing first one seems to be faster at least on small scale.
One could consider the modules groupby and views_calc, but I assume they are not acceptable for you.
Additionally, you can accomplish this with a custom module.