unique

问题 My process runs multiple instances (processes) and multiple threads and all of them write to the same database. As soon as the request is placed, a unique req id is generated for the record to be added to the proprietary db. Here are our limitations: It cannot be more than 9 char length, needs to have hhmmss as the first 6 chars. We decided to use ms for the last 3 digits to complete the 9 chars and we are doing all this using gettimeofday() . However, with increased traffic, there are now

问题 I am creating a C wrapper that can read types of data structures stored in text files. The interface should be that I can generate a unique id mapped to a unique data structure and modify through wrapper functions via the unique id. The problem is that I need to be able to generate a unique id to map. I would like to not use any external library. Is there any way to do this without any large overhead? 回答1: I guess that you are wanting the id to be (practically speaking) world-wide unique (so

问题 I have the following challenge that I need to create unique object tuples out of object lists. The speical challenge is here how I can do it for dynamic list sizes (n-dimension)? It is easy in case you have a fixed dimension. I hope somebody knows a third party API or has some hints for me how I can reach this. The exampel below shows it for a 3 lists, so it is easier to explain. I have the objects sorted by its class in a list e.g. lista = {a1,a2} listb = {b1,b2,b3} listc = {c1,c2} I like to

问题 There doesn't seem to be a similar question anywhere. I need this to just loop through each unique value, and then kick out how many are the same but, somehow I'm using mysqli_num_rows wrong. Thank you in advance. //This portion fetches unique entries that aren't empty $query = "SELECT DISTINCT burger "; $query .= "FROM newbob "; $query .= "WHERE burger != '' "; $query .= "ORDER BY burger ASC "; $result = mysqli_query($dbc, $query); if (!$result){ die ("Database query failed."); } //and I

问题 I have a list of Invoices and all the Products on each Invoice. Each Invoice can have multiples of the same product class InvoiceProducts { public int InvoiceID { get; set; } public int ProductID { get; set; } } var list = new List<InvoiceProducts>(); list.Add(new { InvoiceID = 7000, ProductID=15}); list.Add(new { InvoiceID = 7000, ProductID=10}); list.Add(new { InvoiceID = 7000, ProductID=10}); list.Add(new { InvoiceID = 7000, ProductID=15}); list.Add(new { InvoiceID = 7010, ProductID=12});

问题 Im trying to find a statement for selecting unique values. Not like distinct/unique, cause these just remove duplicates. I want to get a list of all the values that are unique, only one entry. For instance: Values: 1, 2, 3, 4, 4, 5, 5, 6. I would like to get: 1, 2, 3, 6. EDIT: The problem is: What actors (name and number of movies) have played roles with a unique character name in more than 199 movies? These are my tables: Table "public.filmparticipation" Column | Type | Modifiers ----------+

问题 i have the same problem here :SQL select rows with only a certain value in them but the solution that i have found work only for one value given, i mean that i want it to work for a number of values {2 or +}, for example : Col 1 Col 2 Col 3 1 A 1 2 A 2 3 B 1 4 C 1 5 C 2 6 D 1 7 C 3 I want to get all rows that just contain cols3 = 1 and cols3 =2 ONLY , (just values 1 and 2) and the output will be : "A" for the table given, i dont want to have C because it has another values of cols 3 != of 1

问题 I have a json file(input.json) which looks like this : {"header1":"a","header2":1a, "header3":1a, "header4":"apple"}, {"header1":"b","header2":2a, "header3":2a, "header4":"orange"} {"header1":"c","header2":1a, "header3":2a, "header4":"banana"}, {"header1":"d","header2":2a, "header3":1a, "header4":"apple"}, {"header1":"a","header2":2a, "header3":1a, "header4":"banana"}, {"header1":"b","header2":1a, "header3":2a, "header4":"orange"}, {"header1":"b","header2":1a, "header3":1a, "header4":"orange"

问题 I don't want my database id's to be sequential, so I'm trying to generate uids with this code: $bin = openssl_random_pseudo_bytes(12); $hex = bin2hex($bin); return base_convert($hex, 16, 36); My question is: how many bytes would i need to make the ids unique enough to handle large amounts of records (like twitter)? 回答1: You might considering something like the way tinyurl and other shortening services work. I've used similar techniques, which guarantees uniqueness until all combinations are

问题 I need to pull from MYSQL a value , than change forward the value and insert in to the mysql. for example : $str = mysql_fetch_assoc(mysql_query('SELECT `str_id` FROM `ids` ORDER BY `num_id` DESC LIMIT 1 ')); // = aaa $str = $str++; // aaa -> aab // than check if "aab" key already exist // if not , insert as key as "aab" as for this algorithm there is a risk that this script runs from the two sides of the globe and two unique keys will be sign as "aab".. how can i do this without risk of sign