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Prevent auto increment on MySQL duplicate insert

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Using MySQL 5.1.49, I'm trying to implement a tagging system the problem I have is with a table with two columns: id(autoincrement) , tag(unique varchar) (InnoDB) When using query, INSERT IGNORE INTO tablename SET tag="whatever" , the auto increment id value increases even if the insert was ignored. Normally this wouldn't be a problem, but I expect a lot of possible attempts to insert duplicates for this particular table which means that my next value for id field of a new row will be jumping way too much. For example I'll end up with a table with say 3 rows but bad id 's 1 | test 8 | testtext

How do I use SELECT GROUP BY in DataTable.Select(Expression)?

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问题 I try to remove the duplicate rows by select a first row from every group. For Example PK Col1 Col2 1 A B 2 A B 3 C C 4 C C I want a return: PK Col1 Col2 1 A B 3 C C I tried following code but it didn't work: DataTable dt = GetSampleDataTable(); //Get the table above. dt = dt.Select("SELECT MIN(PK), Col1, Col2 GROUP BY Col1, Col2); 回答1: DataTable 's Select method only supports simple filtering expressions like {field} = {value} . It does not support complex expressions, let alone SQL/Linq

How to persist @ManyToMany relation - duplicate entry or detached entity

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问题 I want to persist my entity with ManyToMany relation. But i have some problem during persisting process. My entities : @Entity @Table(name = "USER") public class User implements Serializable { private static final long serialVersionUID = 1L; @Id @Column(name = "ID") @GeneratedValue(strategy = GenerationType.IDENTITY) Long userId; @Column(name = "NAME", unique = true, nullable = false) String userName; @Column(name = "FORNAME") String userForname; @Column(name = "EMAIL") String userEmail;

What's the most Pythonic way to identify consecutive duplicates in a list?

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I've got a list of integers and I want to be able to identify contiguous blocks of duplicates: that is, I want to produce an order-preserving list of duples where each duples contains (int_in_question, number of occurrences). For example, if I have a list like: [0, 0, 0, 3, 3, 2, 5, 2, 6, 6] I want the result to be: [(0, 3), (3, 2), (2, 1), (5, 1), (2, 1), (6, 2)] I have a fairly simple way of doing this with a for-loop, a temp, and a counter: result_list = [] current = source_list[0] count = 0 for value in source_list: if value == current: count += 1 else: result_list.append((current, count))

Is there a no-duplicate List implementation out there?

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问题 I know about SortedSet, but in my case I need something that implements List , and not Set . So is there an implementation out there, in the API or elsewhere? It shouldn\'t be hard to implement myself, but I figured why not ask people here first? 回答1: There's no Java collection in the standard library to do this. LinkedHashSet<E> preserves ordering similarly to a List , though, so if you wrap your set in a List when you want to use it as a List you'll get the semantics you want. Alternatively

Will copy-on-write prevent data duplication on arrays?

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问题 I am programming a web API client in PHP that parses CSV data into associative arrays and I want to protect my users from data-duplication when using these arrays. My users will never be writing to these arrays (theoretically they could but it makes no sense in practice). Now my question is... if my users pass these arrays around as arguments to methods, will PHP\'s copy-on-write mechanism prevent data-duplication or will any method that doesn\'t explicitly accept a reference to an array

How to remove duplicates only if consecutive in a string? [duplicate]

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问题 This question already has an answer here: Removing elements that have consecutive duplicates 4 answers For a string such as \'12233322155552\' , by removing the duplicates, I can get \'1235\' . But what I want to keep is \'1232152\' , only removing the consecutive duplicates. 回答1: Microsoft / Amazon job interview type of question: This is the pseudocode, the actual code is left as exercise. for each char in the string do: if the current char is equal to the next char: delete next char else

Get the keys for duplicate values in an array

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问题 I have the following array: $myarray = Array(\"2011-06-21\", \"2011-06-22\", \"2011-06-22\", \"2011-06-23\", \"2011-06-23\", \"2011-06-24\", \"2011-06-24\", \"2011-06-25\", \"2011-06-25\", \"2011-06-26\"); var_dump($myarray); Result: Array ( [0] => 2011-06-21 [1] => 2011-06-22 [2] => 2011-06-22 [3] => 2011-06-23 [4] => 2011-06-23 [5] => 2011-06-24 [6] => 2011-06-24 [7] => 2011-06-25 [8] => 2011-06-25 [9] => 2011-06-26 ) Now how can I display the keys with duplicate values? Here the function

IntegrityError duplicate key value violates unique constraint - django/postgres

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问题 I\'m following up in regards to a question that I asked earlier in which I sought to seek a conversion from a goofy/poorly written mysql query to postgresql. I believe I succeeded with that. Anyways, I\'m using data that was manually moved from a mysql database to a postgres database. I\'m using a query that looks like so: \"\"\" UPDATE krypdos_coderound cru set is_correct = case when t.kv_values1 = t.kv_values2 then True else False end from (select cr.id, array_agg( case when kv1.code_round

Oracle Equivalent to MySQL INSERT IGNORE?

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问题 I need to update a query so that it checks that a duplicate entry does not exist before insertion. In MySQL I can just use INSERT IGNORE so that if a duplicate record is found it just skips the insert, but I can\'t seem to find an equivalent option for Oracle. Any suggestions? 回答1: Check out the MERGE statement. This should do what you want - it's the WHEN NOT MATCHED clause that will do this. Do to Oracle's lack of support for a true VALUES() clause the syntax for a single record with fixed