relational

I have a SQL table like so: Update: I'm changing the example table as the existing hierarchical nature of the original data (State, Cities, Schools) is overshadowing the fact that a simple relationship is needed between the items. entities id name 1 Apple 2 Orange 3 Banana 4 Carrot 5 Mushroom I want to define two-way relationships between these entities so a user viewing one entity can see a list of all related entities. The relationships are defined by an end user. What is the best way to represent these relationships in the database and subsequently query and update them? One way as I see it

Duplicates Why should I use document based database instead of relational database? Pros/Cons of document based database vs relational database I don't know much about Google's Bigtable but am wondering what the difference between Google's Bigtable and relational databases like MySQL is. What are the limitations of both? tylerl Bigtable is Google's invention to deal with the massive amounts of information that the company regularly deals in. A Bigtable dataset can grow to immense size (many petabytes) with storage distributed across a large number of servers. The systems using Bigtable include

I need some help with the JPA Framework. I've read some answers "kind of" about this topic but I couldn't reach any conclusion. First heres an examplo of the design i'm wooking with. @BusinessObject public class ClassA { @Column(name = "ID", nullable = false) private Long id; @OneToMany(mappedBy = "classAAttr") private Collection<ClassAB> classABCollection; //STUFF AND OTHER COLUMNS..... } public class ClassAB { @Column(name = "ID", nullable = false) private Long id; @JoinColumn(name = "TABLE_A_ID", referencedColumnName = "ID") @ManyToOne private ClassA classAAttr; @JoinColumn(name = "TABLE_B

What is the BCNF decomposition for these dependencies? A->BCD BC->DE B->D D->A What is the process to get to the answer? We can first convert the relation R to 3NF and then to BCNF. To convert a relation R and a set of functional dependencies( FD's ) into 3NF you can use Bernstein's Synthesis . To apply Bernstein's Synthesis - First we make sure the given set of FD's is a minimal cover Second we take each FD and make it its own sub-schema. Third we try to combine those sub-schemas For example in your case: R = {A,B,C,D,E} FD's = {A->BCD,BC->DE,B->D,D->A} First we check whether the FD's is a

I have a relational database with three tables. The first containts id's that relate to the second. The second contains id's that relate to the third. The third contains the results I am after. Is it possible with a single query to query an id in the first table which gives all results from the third table that relate to it? Sorry I am new to mySQL. Mysql Join Try this select * from table1 t1 join table2 t2 on t1.t2ref = t2.id join table3 t3 on t2.t3ref = t3.id Add a where clause to search for certain rows in table1 where t1.field = 'value' Rik Heywood yes SELECT t3.* FROM t1, t2, t3 WHERE t1