unique

问题 I want to create a table structure like this in MySQL: id | area | name ----+----------+------------ 1 | name-1 | test | | 1 | name-1 | value2 | | 2 | name-2 | test-value | | 3 | name-3 | test | | 3 | name-3 | test ie. the primary key will be: primary_key( id, area ) and the id will be auto_increment , but i only want the id to increment for every new unique area is this possible? 回答1: What you want is not possible. You want id and area to be the primary key but in your example they are not

问题 I am working on a project which shows rss feeds from different sites. I keep them in the database, every 3 hours my program fetches and inserts them into sql database. I want unique records for providers not to show duplicate content. But problem is some providers do not give GUID field, and some others gives GUID field but not pubdate.. And some others does not even give GUID or PubDate just title and link. So to keep rss feeds uniqe in sql server what would be the best way? Should I check

问题 I have 2 tables: pages and menu I want to have a pointer into menu table as foreign key to pages.id. The problem is that some menu rows don't have a link to page. When someone clicks in the link opens a submenu. How i do this in phpmyadmin? The match i want is 1 to 1 or 1 to 0 Thanks Maybe if i have a row to pages that has id=some_id with pages.body=null and all the menus that i want to have no submenu would have menu.pages_id=some_id Is this the right way to do that i want? 回答1: Using some

问题 Yii2 Unique Validation not working for combination of employee id and company id Below are my model code. public function rules() { return [ [['company_id', 'role_id'], 'required'], [['company_id', 'role_id', 'status'], 'integer'], [['employee_id'], 'string', 'max' => 15], [['report_to'], 'string', 'max' => 16], [['id',],'safe'], ['employee_id', 'unique', 'targetAttribute' => ['company_id', 'employee_id'], 'message' => 'The combination of Company ID and Employee ID has already been taken.'] /

问题 I have an existing table with records in it and I've just added a new column ver which I would like to be unique. create table foo ( bar text, ver integer ); select * from foo; bar ver --- --- one null two null three null I'm struggling with how to do this for some reason. I want to do something like: update foo set ver = ( select generate_series(1, 1000) ); or maybe update foo set ver = v from (select generate_series(1, 1000) as v ); ...but of course neither of those work. Can anyone point

问题 Using this code: from itertools import product list1 = ['Gabe', 'Taylor', 'Kyle', 'Jay'] list2 = ['Gabe', 'Taylor', 'Kyle', 'Jay', 'James', 'John', 'Tyde','Chris', 'Bruno', 'David'] list3 = ['Gabe', 'Taylor', 'Kyle', 'Jay', 'James', 'John', 'Tyde','Chris', 'Bruno', 'David'] list4 = ['Kyle', 'James', 'John', 'Tyde','Bruno', 'Drew', 'Chris'] list5 = ['James', 'John', 'Brendan','Tim', 'Drew' ] FinalList = [] for x in product(list1, list2, list3, list4, list5): # check for duplicates if len(set(x

问题 I have a collection of addresses. Let's simplify and say the only fields are postcode , city , street , streetnumber and name . I'd like to be able to suggest a list of streets when the user enters a postcode, a city and some query for the street. For example, if the user, in a HTML form, enters: postcode: 75010 city: Paris street: rue des I'd like to get a list of streets like 'rue des petites écuries' 'rue des messageries' ... 'rue du faubourg poissonnière' ... that I could suggest to the

问题 I'm using following peace of code to output an array: echo "======output without array_unique====="; var_dump($selected); echo "=====output with array_unique====="; var_dump(array_unique($selected));die; And the output is: ======output without array_unique===== array 0 => array 'uri' => string 'http://localhost/conferences/tags/0caf4c990e0a385156b33fee58e7e3fb' (length=63) 'tag' => string '1' (length=1) 'weight' => float 4 'selected' => string 'select' (length=6) 1 => array 'uri' => string

问题 in reference to the excel screen capture below, I'm looking for a formula solution that counts the number of unique values in Column B (Colour) for each ID number in Column A. I've imputed the desired result in Column C. So, for instance, ID 1 (A2) has only one unique colour, Grey (B2), which would return a 1 in C2. ID 2 has only one unique colour, yellow (B3, B4), and returns 1 in C3 and C4. ID 3, has two unique colours, Blue and Purple, thus returning a 2 in C5 through C8. Etc. Because this

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Generating random numbers effectively I need to generate random numbers in my C++ application. I know from reading these two articles -- http://www.cprogramming.com/tutorial/random.html write a c function that generates one random number, or a pair of random numbers, or a triplet of random numbers given the particular ranges -- that random numbers can be generated using srand() and rand() but in both cases the