constraints

问题 I am having trouble creating a unique index respecting null -values in MySQL v5.6.20. I checked similar answers here. but couldn't solve my problem with them. Desired behavior I want a table which has references to three other table ( date_list_assignment ). The purpose of the table is the mapping of date_list -entries to course categories and/or date_list categories. The first column is therefore mandatory, while the latter two are not. If the latter two are null the date list entries is

问题 There's been a lot of questions about how to make dynamic cell height using Autolayout and TextView inside it. Here's the story I follow this article iOS dynamic table view cells with varying row height and Autolayout. In this case, we replace the 2nd label in the article with a TextView, with the same set of constraints The TextView does not have intrinsic content size as the Label. So we must use sizeThatFits and creating height constraint on the TextView, like this. This height constraint

问题 According to the DBUnit docs link it should support using a CLEAN_INSERT when using a DatabaseSequenceFilter. I get the following exception when attempting this com.sybase.jdbc2.jdbc.SybSQLException: Dependent foreign key constraint violation in a referential integrity constraint. dbname = 'my_db', table name = 'tbl_child', constraint name = 'fk_tbl_child_parentid'. My tables look like this: CREATE TABLE dbo.tbl_parent ( parent_id numeric(19,0) IDENTITY, ... ) CREATE TABLE dbo.tbl_child (

问题 According to the DBUnit docs link it should support using a CLEAN_INSERT when using a DatabaseSequenceFilter. I get the following exception when attempting this com.sybase.jdbc2.jdbc.SybSQLException: Dependent foreign key constraint violation in a referential integrity constraint. dbname = 'my_db', table name = 'tbl_child', constraint name = 'fk_tbl_child_parentid'. My tables look like this: CREATE TABLE dbo.tbl_parent ( parent_id numeric(19,0) IDENTITY, ... ) CREATE TABLE dbo.tbl_child (

问题 I have these two tables Table: Guards ID int Name varchar Rank int Table: Squads SquadId Leader SquadName The Leader column points to the ID column in the Guard table and I'm trying to create a constraint that checks if the Rank column linked to the guard id provided as the leader is a specific value (in this case 1) Is this possible or do I have to use a trigger? 回答1: You need to add a CHECK constraint. I'd wrap the constraint into a function since you need to check another table's value.

问题 How can I use 'Check' statement to validate field value in mysql? look at this page, in the manual didn't discussed about check keyword In MySql Workbench and Navicat for mysql , there is not exists any options to set constraints or check. 回答1: MySQL does not enforce CHECK constraints. It parses the check constraint clause, but silently ignores it. You'd have to use a trigger to validate data. 来源： https://stackoverflow.com/questions/5131971/how-can-i-use-check-statement-to-validate-field

问题 Is there a possibility to tell MiniZinc to project solutions on a subset of the set of variables? Or is there any other way to enumerate all solutions that are unique wrt to evaluation of some subset of variables? I have tried to use FlatZinc annotations directly in MiniZinc, but it does not work, since the flattening process adds more defines_var annotations and my annotations are ignored. 回答1: I tried the following model in MiniZinc 2.0 (https://www.minizinc.org/2.0/index.html) and this

问题 I have a prototype tableview cell, with a custom view inside of the tableview cell. The view controller that contains the tableview will only be displayed in landscape mode. The goal is for the UIView that is inside of the tableview cell to resize it's width based on the form factor. So for example there might be a 20pt spacing on the left and right and then the uiview resizes it's width to fill the rest of the space. I'm hoping to do this with storyboard and autolayout. In 3.5 inch form

问题 The question Given a MiniZinc array of strings: int: numStats; set of int: Stats = 1..numStats; array[Stats] of string: statNames; ... with data loaded from a MiniZinc data file: numStats = 3; statNames = ["HEALTH", "ARMOR", "MANA"]; How can one look up the index of a specific string in the array? For example, that ARMOR is located at position 2. The context I need to find an optimal selection of items with regard to some constraints on their stats. This information is stored in a 2D array

问题 Note: This is the two-multipliers variation of this problem Given a set A , consisting of floats between 0.0 and 1.0, find a smallest set B such that for each a in A , there is either a value where a == B[x] , or there is a pair of unique values where a == B[x] * B[y] . For example, given $ A = [0.125, 0.25, 0.5, 0.75, 0.9] A possible (but probably not smallest) solution for B is $ B = solve(A) $ print(B) [0.25, 0.5, 0.75, 0.9] This satisfies the initial problem, because A[0] == B[0] * B[1] ,