Database Fundamentals
... means that the values present in some individual attribute (or set of attributes) must always provide enough information to allow a unique identification of every tuple in the relation. In a relational database, these identifying values are known as key values or just as the key. Sometimes more than ...
... means that the values present in some individual attribute (or set of attributes) must always provide enough information to allow a unique identification of every tuple in the relation. In a relational database, these identifying values are known as key values or just as the key. Sometimes more than ...
MYCH3
... A foreign key must point to a primary key. In logic, we can introduce names to denote entities. In object-oriented models, we can have object IDs. In the relational model, primary keys play the role of names of entities. Base tables define names for entities. E.g. student ids in Students. Foreign ...
... A foreign key must point to a primary key. In logic, we can introduce names to denote entities. In object-oriented models, we can have object IDs. In the relational model, primary keys play the role of names of entities. Base tables define names for entities. E.g. student ids in Students. Foreign ...
Databases: storing and retrieving information
... Choosing A Primary Key •A primary key must be unique to each record because it is the one thing that distinguishes them. •If there’s at least one instance where the attributes of two records can take on the same value then that attribute cannot be a primary key. (When in doubt verify with your user ...
... Choosing A Primary Key •A primary key must be unique to each record because it is the one thing that distinguishes them. •If there’s at least one instance where the attributes of two records can take on the same value then that attribute cannot be a primary key. (When in doubt verify with your user ...
Relational Database Design
... • What normalization is and what role it plays in database design • About the normal forms 1NF, 2NF, 3NF, BCNF, and 4NF • How normal forms can be transformed from lower normal forms to higher normal forms • That normalization and E-R modeling are used concurrently to produce a good database design • ...
... • What normalization is and what role it plays in database design • About the normal forms 1NF, 2NF, 3NF, BCNF, and 4NF • How normal forms can be transformed from lower normal forms to higher normal forms • That normalization and E-R modeling are used concurrently to produce a good database design • ...
21SCS157BL6FDSQL
... X is a proper subset of some key K. Such a dependency is sometimes called a partial dependency. In this case, we store (X,A) pairs redundantly. X is not a proper subset of any key. Such a dependency is sometimes called a transitive dependency, because it means we have a chain of dependencies K ...
... X is a proper subset of some key K. Such a dependency is sometimes called a partial dependency. In this case, we store (X,A) pairs redundantly. X is not a proper subset of any key. Such a dependency is sometimes called a transitive dependency, because it means we have a chain of dependencies K ...
09 - SQL basics, including scripts and CGI
... MySQL is a particular version of a relational SQL-compatible database known for its efficiency. It is widely used and free for non-commercial applications. See http://www.mysql.com/ for details, in particular for downloading the free community edition. Other widely used SQL databases are Oracle, Mic ...
... MySQL is a particular version of a relational SQL-compatible database known for its efficiency. It is widely used and free for non-commercial applications. See http://www.mysql.com/ for details, in particular for downloading the free community edition. Other widely used SQL databases are Oracle, Mic ...
Combining SQL and Conventional Programming Languages
... Shortcomings of SQL Relational data model doesn't match well with data model of conventional programming languages (e.g., data structure mismatch) No pointers, loops or branches in SQL No convenient input and output (e.g., formatting) ...
... Shortcomings of SQL Relational data model doesn't match well with data model of conventional programming languages (e.g., data structure mismatch) No pointers, loops or branches in SQL No convenient input and output (e.g., formatting) ...
select
... The SQL standard defines embeddings of SQL in a variety of programming languages such as C, Java, and Cobol. A language to which SQL queries are embedded is referred to as a host language, and the SQL structures permitted in the host language comprise embedded SQL. The basic form of these languages ...
... The SQL standard defines embeddings of SQL in a variety of programming languages such as C, Java, and Cobol. A language to which SQL queries are embedded is referred to as a host language, and the SQL structures permitted in the host language comprise embedded SQL. The basic form of these languages ...
PPT - Computer Science, NMSU
... Domain of a Type • domain(T) is the set of all objects that conform to type T. Namely: – domain(Integer) = set of all integers, domain(String) = set of all strings, etc. – domain(T), where T is reference type is the extent of T, ie, oids of all objects in class T – domain([A1: T1, …, An: Tn]) is th ...
... Domain of a Type • domain(T) is the set of all objects that conform to type T. Namely: – domain(Integer) = set of all integers, domain(String) = set of all strings, etc. – domain(T), where T is reference type is the extent of T, ie, oids of all objects in class T – domain([A1: T1, …, An: Tn]) is th ...
Select * from - anuradhasrinivas
... SQL:1999 supports functions and procedures Functions/procedures can be written in SQL itself, or in an external programming language Functions are particularly useful with specialized data types such as images and geometric objects Example: functions to check if polygons overlap, or to compare ...
... SQL:1999 supports functions and procedures Functions/procedures can be written in SQL itself, or in an external programming language Functions are particularly useful with specialized data types such as images and geometric objects Example: functions to check if polygons overlap, or to compare ...
SQL Queries - subqueries and joining
... MovieInformation database, we get a result with 49 rows… • 49 = 7 x 7. All combinations of Movie records (7) and Actor records (7) • All fields from both tables are included • This is rarely what we want… RHS – SOC ...
... MovieInformation database, we get a result with 49 rows… • 49 = 7 x 7. All combinations of Movie records (7) and Actor records (7) • All fields from both tables are included • This is rarely what we want… RHS – SOC ...
SQL Server and SQL
... We will use SQL server because it is very popular in the industry today, and we can use it for free via the Microsoft DreamSpark Premium Subscription – which is available for the students and staff at Telemark University College, or use the Express version which is available for free for everybo ...
... We will use SQL server because it is very popular in the industry today, and we can use it for free via the Microsoft DreamSpark Premium Subscription – which is available for the students and staff at Telemark University College, or use the Express version which is available for free for everybo ...
lecture27
... Size Estimation Estimating the size of a natural join, R ⋈A S • When the set of A values are disjoint, then T(R ⋈A S) = 0 • When A is a key in S and a foreign key in R, then T(R ⋈A S) = T(R) • When A has a unique value, the same in R and S, then T(R ⋈A S) = T(R) T(S) ...
... Size Estimation Estimating the size of a natural join, R ⋈A S • When the set of A values are disjoint, then T(R ⋈A S) = 0 • When A is a key in S and a foreign key in R, then T(R ⋈A S) = T(R) • When A has a unique value, the same in R and S, then T(R ⋈A S) = T(R) T(S) ...
PHP Bible – Chapter 16: Displaying Queries in Tables
... columns have no independent existence – each row has some number of table data items () which will produce a nice
rectangular array only if there are the same number of TDs for
every TR within a TABLE
By contrast, fields (aka columns) in database tables are the more
primary entity – defining a t ...
... columns have no independent existence – each row has some number of table data items (
MCQ Of SQL Server Set-2
... 14) The collection of information stored in a database at a particular moment is called as ...... A. schema B. instance of the database C. data domain D. independence ...
... 14) The collection of information stored in a database at a particular moment is called as ...... A. schema B. instance of the database C. data domain D. independence ...
A Methodology for Database System Performance Evaluation
... each query type. We hypothesized that selecting 1 tuple via a clustered index or hashing would be a type I query and that selecting a small number (100 out of 10,000) tuples using a non-clustered index would be a type II query. We had no solid leads about what queries would correspond to query types ...
... each query type. We hypothesized that selecting 1 tuple via a clustered index or hashing would be a type I query and that selecting a small number (100 out of 10,000) tuples using a non-clustered index would be a type II query. We had no solid leads about what queries would correspond to query types ...