I've got a dictionary, something like Dictionary<Foo,String> fooDict I step through everything in the dictionary, e.g. foreach (Foo foo in fooDict.Keys) MessageBox.show(fooDict[foo]); It does that in the order the foos were added to the dictionary, so the first item added is the first foo returned. How can I change the cardina...
Are there generally accepted computer science terms for one-to-one and one-to-many relationships? Something similar to the terms "aggregation", "generalization", and "association," but strictly pertaining to the cardinality of the relationship? ...
I have added a FULLTEXT index to one of my MySQL database tables as follows: ALTER TABLE members ADD FULLTEXT(about,fname,lname,job_title); The problem is that using phpmyadmin I can see the cardinality of my new index is only 1. Does this mean the index will never be used? I have run a analyze table command but it didn't seem to do ...
When collecting requirements from business users, I run into a point where I need to understand the cardinality between two concepts in the business user's domain. This is usually something I want to know early in the process, since it affects database design which is hard to change later. For example, the busines user may have a domai...
I have ran into some problems with MySQL that causes our index cardinality to show up as "NULL". I have noticed that for an index with multiple columns, only the Last column has an actual cardinality value. I have written this query but I want to confirm that there is nothing that I am missing: SELECT s.TABLE_SCHEMA, s.TABLE_NAM...
Is the MySQL cardinality number related to the auto-increment counter? ...
I'm mainly an Actionscript developer and by no means an expert in SQL, but from time to time I have to develop simple server side stuff. So, I thought I'd ask more experienced people about the question in the title. My understanding is that you don't gain much by setting an index in a column that will hold few distinct values. I have a ...
I am attempting to reverse engineer a Database that is in Oracle. I have been able to find the main keys and the referential integrity rules that correspond to the Foreign Keys but cannot locate where the modality/cardinality rules are stored. Any help regarding to which table to look in or a sample query would be greatly appreciated. ...
I have a general question about the way that database indexing works, particularly in mysql. Let's say I have a table with a million rows with a column "ClientID" that is distributed relatively equally among 30 values. Thus, this column is very low cardinality (30) relative to the primary key (1 million). Now, I understand that you ...
Hi, With the following entity relationship structure I'm struggling to figure out if the relationship between the LOAN and ITEM entities is valid? The weak entity of LOAN uses a partial key of 'loan_dateLeant' and the primary keys from CUSTOMER and ITEM to form LOANs primary key. However LOAN has a 'one to many' relationship with ITEM ...
Say you have a MySQL 5.0 MyISAM table with 100 million rows, with one index (other than primary key) on two integer columns. From my admittedly poor understanding of B-tree structure, I believe that a lower cardinality means the storage efficiency of the index is better, because there are less parent nodes. Whereas a higher cardinality ...
How does SQL Server determine whether a table column has low cardinality? The reason I ask is because query optimizer would most probably not use an index on a gender column (values 'm' and 'f'). However how would it determine the cardinality of the gender column to come to that decision? On top of this, if in the unlikely event that I...
I have a UML diagram of what I need my database schema to look like. This diagram includes roles and cardinality. How can I enforce cardinality in Postgres? ...
dear all i am using jena how can i get mincardinality of a property? thanks... ...
Hi, I am searching for a extensional definition for the following set: E := { m | m subset {a,b,c,d} and |m| = 2} My idea is E := {{a,b}, {a,c}, {a,d}, {b,c}, {b,d}, {c,d}, {a,a}, {b,b}, {c,c}, {d,d}} any ideas? ...