## Database System ConceptsThis popular text in database systems is used in departments of computer science, computer engineering, and electrical engineering. The revision includes more material on SQL, relational models, logical databases, "QB" and "Datalog." |

### From inside the book

Results 1-3 of 96

Page 83

Find all customers who have an account at all branches located in Brooklyn: {<c

> I V x,y,z (—i (<x,y,z > e branch) \j z + "Brooklyn" v (3 a,n (<x,a,c,n > e deposit)))}

In English, we interpret the above

tuples <c > such that for all (branch-name, assets, branch-city) tuples, <x,y,z >, at

least one of the following is true": • <x,y,z > is not a tuple of the branch relation (

and, therefore, does not pertain to a branch in Brooklyn). • z does not have the

value ...

Find all customers who have an account at all branches located in Brooklyn: {<c

> I V x,y,z (—i (<x,y,z > e branch) \j z + "Brooklyn" v (3 a,n (<x,a,c,n > e deposit)))}

In English, we interpret the above

**expression**as "the set of all (customer- name)tuples <c > such that for all (branch-name, assets, branch-city) tuples, <x,y,z >, at

least one of the following is true": • <x,y,z > is not a tuple of the branch relation (

and, therefore, does not pertain to a branch in Brooklyn). • z does not have the

value ...

Page 84

We say that an

following hold: 1. All values that appear in tuples of the

from dom(P). 2. For every "there exists" subformula of the form 3 x (P1(x)), the

subformula is true if and only if there is a value x in dom(P{) such that P1(x) is true

. 3. For every "for all" subformula of the form V x (P,(x)), the subformula is true if

and only if P,(x) is true for all values x from dom(Px). The purpose of the

additional rules is ...

We say that an

**expression**{<*,, x2, . . . , xn> I P (x,, x2, . . . , x„)} is safe if all of thefollowing hold: 1. All values that appear in tuples of the

**expression**are valuesfrom dom(P). 2. For every "there exists" subformula of the form 3 x (P1(x)), the

subformula is true if and only if there is a value x in dom(P{) such that P1(x) is true

. 3. For every "for all" subformula of the form V x (P,(x)), the subformula is true if

and only if P,(x) is true for all values x from dom(Px). The purpose of the

additional rules is ...

Page 282

Since a relational query can be

without the use of a host language, it is possible to perform automatically a

substantial amount of query optimization. In this chapter, we present the most

useful techniques for efficient query processing. Before query processing can

begin, the system must translate the query into a usable form. A language such

as SQL is suitable for human use, but ill-suited to be the system's internal

representation of a ...

Since a relational query can be

**expressed**entirely in a relational query languagewithout the use of a host language, it is possible to perform automatically a

substantial amount of query optimization. In this chapter, we present the most

useful techniques for efficient query processing. Before query processing can

begin, the system must translate the query into a usable form. A language such

as SQL is suitable for human use, but ill-suited to be the system's internal

representation of a ...

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User Review - IvanIdris - LibraryThingThis book teaches about the inner workings, the nuts and bolts of databases without requiring a lot of prior knowledge: Data Models Relational Databases Object Based Databases and XML Data Storage and ... Read full review

### Contents

EntityRelationship Model | 23 |

Relational Commercial Languages | 97 |

Integrity Constraints | 149 |

Copyright | |

38 other sections not shown

### Other editions - View all

Database Systems Concepts with Oracle CD Abraham Silberschatz,Henry F. Korth,S. Sudarshan No preview available - 2001 |

### Common terms and phrases

account-number algorithm allows application programs attributes B+-tree balance bank BCNF block borrow branch-city branch-name bucket buffer candidate key cascading rollback Chapter commit compute concurrency control conflict serializable consider constraints contains corresponding CustAcct customer-city customer-name data item data model database design database management database system DBTG deadlock decomposition defined delete discussed disk domain domain relational calculus Downtown E-R diagram employees ensure entity set example execution expression functional dependencies hash function implementation insert join loan loan-number log records main memory modification multivalued dependencies node object-oriented Perryridge branch pointer primary key query language read(B record type recovery relation scheme relational algebra relational database relational model relationship set require result rollback rule schedule search-key value Section serializability set occurrence stable storage stored strategy structure superkey techniques timestamp transaction tree-structure diagram tuple relational calculus update wait-for graph weak entity write write(Q