Resolution :case Flashy Flashers Inc.

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Advantages of Databases:

1. is possible to reduce redundancy.
2. inconsistency can be avoided to some extent.
3. Data can be shared.
4. may enforce the rules.
5. is possible to apply security restrictions.
6. integrity can be maintained.
7. is possible to balance conflicting requirements.

Database Manager:

1. Define conceptual scheme.
2. Define the internal schema.
3. Liaise with users.
4. Define security and integrity checks.
5. Define backup and recovery procedures.
6. Monitor performance.

DBMS Features:

1. Data Definition.
2. Data Handling.
3. A planned application. Request
4. unplanned.
5. Security and Data Integrity.
6. Recovery and Data Concurrency.
7. Data Dictionary.
8. Performance.

Problem of Distributed Systems:

1. query processing.
2. Catalog Management. Spread
3. Updates.
4. Recovery Control.
5. Concurrency Control.

Cervixweek Before Period

Overview of Relational Algebra:

consists of a set of high level operators that operate on relations. Each of these operators take one or two relations as input and produces a new output ratio.

Codd defined a very specific set of eight operators of this type, in two groups:

Traditional Operations:

# Union: build a relationship consists of all tuples appear in any of the two relationships.

# Intersection: Build a relationship composed of those tuples that appear in both relationships.

# Difference: Make a connection formed by the tuples that appear in the first relationship that does not appear in the second of two specified relations.

Cartesian Product #: From two relationships, build a relationship that contains all possible combinations of tuples.

special relational operations:

# Restriction: extracts tuples specified in a given relationship. Extracts those tuples that satisfy the condition.

# Projection: extracts specified attributes of a given relationship.

# Meeting: From two relationships, build a relationship that contains all possible combinations of tuples, one from each of the two relationships.

# Division: It takes two relations, one binary and one unary, and build a relationship formed by all values \u200b\u200bof an attribute of the binary relation that match all the values \u200b\u200bof the unary relation.