Does anyone know good Object Constraint Language (OCL) tutorial?
I came across couple of questions about OCL expressions. After reading some university slides and googling it I still cannot properly understand it.I wonder if any of you guys know any good resources...
View ArticleOCL (Object Constraint Language) select, use sum for attribute
I'm trying to find an OCL excpression (calculator), but I'm not sure how to get the sum of the attributes of a collection. I have a class Customer and a class Orders. I want to have the sum of all...
View ArticleMySQL INSERT query emits database error: "Cannot add or update a child row: a...
Below error message show up on data entry.Error Number: 1452Cannot add or update a child row: a foreign key constraint fails (`mail_sys_db`.`user_plan_original_item`, CONSTRAINT...
View ArticleHow to list all constraints of a table in PostgreSQL?
How to list all constraints (Primary key, Foreign Key, check, unique mutual exclusive, ..) of a table in PostgreSQL?
View ArticleNeed to return a value and its count as 0 when it does not exist with in a...
Below is my exact code as it sits. This query works excellent except for when the teamid does not exist inside the date range. If the teamid does not exist within the date range specified, I want SQL...
View ArticlePostgres caseinsensitive unique key constraint: What is the fast option?
I want to have a case-insensitive unique key on a large table.I'm looking for the fastest approach.I found two options: my_table_a with a generated column and my_table_b with a unique indexCREATE TABLE...
View ArticleEfficiently enumerating multinomials with constant sum - R
Let's say I have an N-side dice with non-uniform probabilities for each side and I throw it M times. Now instead of observing the individual outcomes, we only observe the sum.I have to code the...
View ArticleGo generics: self-referring interface constraint
I have a couple custom types that I need to process in the same way. It seems like a perfect use for generics. In the process, I need to call methods on instances of the types, and those methods return...
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Direct Collocation Oscillating Reconstructed State Trajectory
I am working with the DirectCollocation class and an often getting trajectory solutions with large oscillations (sometimes in the position, almost always in the velocity). These oscillations seem to...
View ArticleDisabling foreign key constraint, still can't truncate table? (SQL Server 2005)
I have a table called PX_Child that has a foreign key on PX_Parent. I'd like to temporarily disable this FK constraint so that I can truncate PX_Parent. I'm not sure how this goes however. I've tried...
View ArticlePostgres unique constraint vs index
As I can understand documentation the following definitions are equivalent:create table foo ( id serial primary key, code integer, label text, constraint foo_uq unique (code, label));create table foo (...
View ArticleOracle: Continuing Inserts with failing deferred constraints
Sorry for the long question, but I would prefer it to be complete.My goal is to create a process to populate an Oracle 11 Database with data created by (and from) an MS-SQL Server.I would like to load...
View ArticleOptaPlanner Constraint Streams: Can complement() use a derived groupBy key
I’m using OptaPlanner Constraint Streams (Java) and want to penalize employees who work less than their minimum required minutes per week, including weeks with zero shifts.I currently have this...
View ArticleSymfony 5 - Use Assert Expression in a form
I would like use Expression constraint from the form.Now, I've my Expression constraint in my entity, like this : /** * @ORM\Column(type="string", length=255) *...
View ArticleMySQL: Add constraint if not exists
In my create script for my database create script looking something like this:CREATE TABLE IF NOT EXISTS `rabbits`( `id` INT UNSIGNED NOT NULL AUTO_INCREMENT, `name` VARCHAR(255) NOT NULL,...
View ArticleInformation schema and Primary Keys
How do I just print out a 'primary key' for the column with the primary key? I get 'primary key' for all the columns if the table has a primary key, instead of the one column with the primary key and...
View ArticleWhy doesn't C++ allow virtual function overrides to be constrained by a...
I tried to write the following code and it was rejected by the compiler:#include <type_traits>struct Base { virtual void f() {}};template <typename T>struct Derived : Base { virtual void...
View ArticleC#: Enum.IsDefined on combined flags
I have this enum:[Flags]public enum ExportFormat{ None = 0, Csv = 1, Tsv = 2, Excel = 4, All = Excel | Csv | Tsv}I am trying to make a wrapper on this (or any, really) enum which notifies on change....
View ArticleIs there any way to enforce a unique constraint on DB from now onwards,...
I'm working with PostgreSQL and I want to enforce a particular column to be unique.But this table has some legacy data in which duplicate of the column are there and they have to be retained...
View ArticlePostgreSQL, unique on combination of two columns
In PostgreSQL, it is easy to set a uniqueness constraint for two columns using CONSTRAINT UNIQUE.For exampleCREATE TABLE someTable ( id serial PRIMARY KEY, col1 int NOT NULL, col2 int NOT NULL, UNIQUE...
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