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There are three major sets of files on disk that compose a DATABASE. All the files are binary. These are
1.) Database files
2.) Control files
3.) Redo LOGS
The most important of these are the database files where the actual data resides. The control files and the redo logs support the functioning of the architecture itself. All three sets of files must be present, open, and available to ORACLE for any data on the database to be useable. Without these files, you cannot ACCESS the database, and the database administrator might have to recover some or all of the database using a BACKUP, if there is one.

There are three major sets of files on disk that compose a database. All the files are binary. These are
1.) Database files
2.) Control files
3.) Redo logs
The most important of these are the database files where the actual data resides. The control files and the redo logs support the functioning of the architecture itself. All three sets of files must be present, open, and available to Oracle for any data on the database to be useable. Without these files, you cannot access the database, and the database administrator might have to recover some or all of the database using a backup, if there is one.

SQL is a nonprocedural language that is designed SPECIFICALLY for data access operations on normalized relational database STRUCTURES. The primary difference between SQL and other conventional programming LANGUAGES is that SQL STATEMENTS specify what data operations should be performed rather than how to perform them.

SQL is a nonprocedural language that is designed specifically for data access operations on normalized relational database structures. The primary difference between SQL and other conventional programming languages is that SQL statements specify what data operations should be performed rather than how to perform them.

You COMMUNICATE with an RDBMS using STRUCTURED QUERY Language (SQL).

You communicate with an RDBMS using Structured Query Language (SQL).

The information in the data DICTIONARY VALIDATES the existence of the objects, provides access to them, and maps the actual physical STORAGE location.

The information in the data dictionary validates the existence of the objects, provides access to them, and maps the actual physical storage location.

Data dictionary is a set of TABLES and DATABASE objects that is stored in a SPECIAL area of the database and maintained EXCLUSIVELY by the kernel.

Data dictionary is a set of tables and database objects that is stored in a special area of the database and maintained exclusively by the kernel.

I/O, SECURITY, Language Processing, Process CONTROL, Storage Management, Logging and Recovery, Distribution Control, TRANSACTION Control, Memory Management, LOCK Management.

I/O, Security, Language Processing, Process Control, Storage Management, Logging and Recovery, Distribution Control, Transaction Control, Memory Management, Lock Management.

Two important PIECES of RDBMS architecture are the KERNEL, which is the software, and the data dictionary, which consists of the system-level data structures used by the kernel to manage the database You might THINK of an RDBMS as an OPERATING system (or set of subsystems), designed specifically for controlling data access; its primary functions are storing, retrieving, and securing data. An RDBMS maintains its own list of authorized users and their associated privileges; manages memory caches and paging; controls locking for concurrent resource usage; dispatches and schedules user REQUESTS; and manages space usage within its table-space structures.

Two important pieces of RDBMS architecture are the kernel, which is the software, and the data dictionary, which consists of the system-level data structures used by the kernel to manage the database You might think of an RDBMS as an operating system (or set of subsystems), designed specifically for controlling data access; its primary functions are storing, retrieving, and securing data. An RDBMS maintains its own list of authorized users and their associated privileges; manages memory caches and paging; controls locking for concurrent resource usage; dispatches and schedules user requests; and manages space usage within its table-space structures.

No.
PRODUCT: Concatenation of EVERY ROW in ONE RELATION with every row in another.
JOIN: Concatenation of rows from one relation and related rows from another.

No.
PRODUCT: Concatenation of every row in one relation with every row in another.
JOIN: Concatenation of rows from one relation and related rows from another.

PROJECTION and SELECTION.

PROJECTION and SELECTION.

Subqueries, or nested queries, are used to bring back a set of rows to be used by the parent query. Depending on how the subquery is written, it can be executed once for the parent query or it can be executed once for each row returned by the parent query. If the subquery is executed for each row of the parent, this is called a CORRELATED subquery.

A correlated subquery can be easily identified if it contains any REFERENCES to the parent subquery columns in its WHERE clause. Columns from the subquery cannot be referenced anywhere else in the parent query. The following example DEMONSTRATES a non-correlated subquery.

Example:

SELECT’ From CUST Where ‘10/03/1990’ IN (Select ODATE From ORDER Where CUST.CNUM = ORDER.CNUM)

Subqueries, or nested queries, are used to bring back a set of rows to be used by the parent query. Depending on how the subquery is written, it can be executed once for the parent query or it can be executed once for each row returned by the parent query. If the subquery is executed for each row of the parent, this is called a correlated subquery.

A correlated subquery can be easily identified if it contains any references to the parent subquery columns in its WHERE clause. Columns from the subquery cannot be referenced anywhere else in the parent query. The following example demonstrates a non-correlated subquery.

Example:

Select’ From CUST Where ‘10/03/1990’ IN (Select ODATE From ORDER Where CUST.CNUM = ORDER.CNUM)

A query with RESPECT to DBMS RELATES to user commands that are used to interact with a data base. The query LANGUAGE can be classified into data DEFINITION language and data manipulation language.

A query with respect to DBMS relates to user commands that are used to interact with a data base. The query language can be classified into data definition language and data manipulation language.

It is one, which KEEPS its Physical STRUCTURE hidden from USER.

It is one, which keeps its Physical Structure hidden from user.

It is a database in which there are no programs or USER access languages. It has no cross-file CAPABILITIES but is user-friendly and PROVIDES user-interface management.

It is a database in which there are no programs or user access languages. It has no cross-file capabilities but is user-friendly and provides user-interface management.

DIFFERENT PHASES are
1.) Analysis phase,
2.) Redo Phase,
3.) Undo phase.

Different phases are
1.) Analysis phase,
2.) Redo Phase,
3.) Undo phase.

A Checkpoint is LIKE a snapshot of the DBMS STATE. By TAKING checkpoints, the DBMS can reduce the amount of WORK to be DONE during restart in the event of subsequent crashes.

A Checkpoint is like a snapshot of the DBMS state. By taking checkpoints, the DBMS can reduce the amount of work to be done during restart in the event of subsequent crashes.

In DISTRIBUTED deadlock DETECTION, the DELAY in propagating local information might cause the deadlock detection algorithms to identify deadlocks that do not really exist. Such situations are called phantom deadlocks and they lead to unnecessary ABORTS.

In distributed deadlock detection, the delay in propagating local information might cause the deadlock detection algorithms to identify deadlocks that do not really exist. Such situations are called phantom deadlocks and they lead to unnecessary aborts.

1. Atomicity: Either all actions are carried out or none are. Users should not have to worry about the effect of INCOMPLETE transactions. DBMS ensures this by undoing the actions of incomplete transactions.
2. AGGREGATION: A concept which is used to model a RELATIONSHIP between a collection of entities and relationships. It is used when we need to express a relationship AMONG relationships.

1. Atomicity: Either all actions are carried out or none are. Users should not have to worry about the effect of incomplete transactions. DBMS ensures this by undoing the actions of incomplete transactions.
2. Aggregation: A concept which is used to model a relationship between a collection of entities and relationships. It is used when we need to express a relationship among relationships.

Once the DBMS informs the user that a transaction has successfully COMPLETED, its EFFECTS should persist EVEN if the system crashes before all its changes are reflected on DISK. This PROPERTY is called durability.

Once the DBMS informs the user that a transaction has successfully completed, its effects should persist even if the system crashes before all its changes are reflected on disk. This property is called durability.

The PHASE that identifies an efficient execution PLAN for EVALUATING a query that has the least estimated cost is REFERRED to as query OPTIMIZATION.

The phase that identifies an efficient execution plan for evaluating a query that has the least estimated cost is referred to as query optimization.

A RDBMS maintains a description of all the data that it contains, INFORMATION about EVERY relation and INDEX that it contains. This information is stored in a COLLECTION of relations maintained by the system called METADATA. It is also called data dictionary.

A RDBMS maintains a description of all the data that it contains, information about every relation and index that it contains. This information is stored in a collection of relations maintained by the system called metadata. It is also called data dictionary.

A RELATION is said to be in DKNF if all constraints and DEPENDENCIES that should hold on the the constraint can be ENFORCED by simply enforcing the domain constraint and KEY constraint on the relation.

A relation is said to be in DKNF if all constraints and dependencies that should hold on the the constraint can be enforced by simply enforcing the domain constraint and key constraint on the relation.

A RELATION schema R is said to be 5NF if for EVERY join dependency {R1, R2, ..., RN} that holds R, ONE the following is TRUE 1.) Ri = R for some i.

A Relation schema R is said to be 5NF if for every join dependency {R1, R2, ..., Rn} that holds R, one the following is true 1.) Ri = R for some i.

A relation schema R is said to be in 4NF if for EVERY Multivalued dependency X Y that holds over R, one of following is TRUE.
1.) X is subset or EQUAL to (or) XY = R.
2.) X is a super key.

A relation schema R is said to be in 4NF if for every Multivalued dependency X Y that holds over R, one of following is true.
1.) X is subset or equal to (or) XY = R.
2.) X is a super key.

A relation schema R is in BCNF if it is in 3NF and satisfls an ADDITIONAL constraint that for every FD X A, X MUST be a candidate KEY.

A relation schema R is in BCNF if it is in 3NF and satisfls an additional constraint that for every FD X A, X must be a candidate key.

A relation schema R is in 3NF if it is in 2NF and for every FD X A either of the following is true
1. X is a Super-key of R.
2. A is a prime ATTRIBUTE of R.
In other WORDS, if every NON prime attribute is non-transitively dependent on PRIMARY key.

A relation schema R is in 3NF if it is in 2NF and for every FD X A either of the following is true
1. X is a Super-key of R.
2. A is a prime attribute of R.
In other words, if every non prime attribute is non-transitively dependent on primary key.

A relation SCHEMA R is in 2NF if it is in 1NF and every non-prime attribute A in R is fully functionally DEPENDENT on primary key.

A relation schema R is in 2NF if it is in 1NF and every non-prime attribute A in R is fully functionally dependent on primary key.

It is based on CONCEPT of full FUNCTIONAL dependency. A functional dependency X Y is full functional dependency if removal of any attribute A from X MEANS that the dependency does not HOLD any more.

It is based on concept of full functional dependency. A functional dependency X Y is full functional dependency if removal of any attribute A from X means that the dependency does not hold any more.

The DOMAIN of ATTRIBUTE MUST include only atomic (SIMPLE, indivisible) values.

The domain of attribute must include only atomic (simple, indivisible) values.

It GUARANTEES that the spurious tuple generation does not occur with respect to RELATION schemas after DECOMPOSITION.

It guarantees that the spurious tuple generation does not occur with respect to relation schemas after decomposition.

A Functional DEPENDENCY is denoted by X Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can FORM a relation STATE r of R. The constraint is for any two tuples TI and T2 in r if tl[XJ = t2[Xj then they have tl[Y] = t2[Y]. This means the value of X component of a tuple uniquely determines the value of component V.

A Functional dependency is denoted by X Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can form a relation state r of R. The constraint is for any two tuples ti and t2 in r if tl[XJ = t2[Xj then they have tl[Y] = t2[Y]. This means the value of X component of a tuple uniquely determines the value of component V.

1. The TUPLE-oriented calculus uses a tuple variables i.e., variable whose only permitted values are tuples of that relation. E.g. QUEL
2. The DOMAIN-oriented calculus has domain variables i.e., variables that range over the UNDERLYING domains instead of over relation. E.g. ILL, DEDUCE.

1. The tuple-oriented calculus uses a tuple variables i.e., variable whose only permitted values are tuples of that relation. E.g. QUEL
2. The domain-oriented calculus has domain variables i.e., variables that range over the underlying domains instead of over relation. E.g. ILL, DEDUCE.

It is an applied predicate calculus specifically TAILORED for RELATIONAL DATABASES proposed by E.F. Codd. E.g. of languages based on it are DSL ALPHA, QUEL.

It is an applied predicate calculus specifically tailored for relational databases proposed by E.F. Codd. E.g. of languages based on it are DSL ALPHA, QUEL.

It is procedural QUERY LANGUAGE. It consists of a set of operations that take one or two RELATIONS as input and produce a NEW RELATION.

It is procedural query language. It consists of a set of operations that take one or two relations as input and produce a new relation.

The High level or Non-procedural DML can specify and RETRIEVE MANY RECORDS in a single DML STATEMENT. This retrieve of a RECORD is said to be Set-at-a-time or Set-oriented.

The High level or Non-procedural DML can specify and retrieve many records in a single DML statement. This retrieve of a record is said to be Set-at-a-time or Set-oriented.

The Low level or PROCEDURAL DML can specify and retrieve each record from a set of RECORDS. This retrieve of a record is SAID to be Record-at-a-time.

The Low level or Procedural DML can specify and retrieve each record from a set of records. This retrieve of a record is said to be Record-at-a-time.

It INTERPRETS DDL statements and record them in TABLES CONTAINING metadata.

It interprets DDL statements and record them in tables containing metadata.

It EXECUTES low-level INSTRUCTION GENERATED by COMPILER.

It executes low-level instruction generated by compiler.

It translates DML statements in a query language into low-level instruction that the query evaluation ENGINE can UNDERSTAND.

It translates DML statements in a query language into low-level instruction that the query evaluation engine can understand.

This language that enable USER to access or manipulate DATA as organised by appropriate data model.
1. Procedural DML or Low level: DML requires a user to SPECIFY what data are NEEDED and how to get those data.
2. Non-Procedural DML or High level: DML requires a user to specify what data are needed without specifying how to get those data.

This language that enable user to access or manipulate data as organised by appropriate data model.
1. Procedural DML or Low level: DML requires a user to specify what data are needed and how to get those data.
2. Non-Procedural DML or High level: DML requires a user to specify what data are needed without specifying how to get those data.

The storage structures and ACCESS methods USED by DATABASE system are SPECIFIED by a set of definition in a special TYPE of DDL called data storage-definition language.

The storage structures and access methods used by database system are specified by a set of definition in a special type of DDL called data storage-definition language.

This language is to SPECIFY the internal schema. This language may specify the MAPPING between TWO schemas.

This language is to specify the internal schema. This language may specify the mapping between two schemas.

It SPECIFIES user VIEWS and their MAPPINGS to the CONCEPTUAL SCHEMA.

It specifies user views and their mappings to the conceptual schema.

A DATA base schema is specifies by a set of DEFINITIONS expressed by a special LANGUAGE called DDL.

A data base schema is specifies by a set of definitions expressed by a special language called DDL.

It is the NUMBER of ENTITY TYPE PARTICIPATING.

It is the number of entity type participating.

Relationship TYPE DEFINES a SET of associations or a relationship set among a given set of ENTITY TYPES.

Relationship type defines a set of associations or a relationship set among a given set of entity types.

The COLLECTION (or SET) of SIMILAR RELATIONSHIPS.

The collection (or set) of similar relationships.

DBMS stands for Database Management System. A DBMS RECEIVES requests from applications and TRANSLATES those requests into actions on a specific database. A DBMS processes SQL statements or uses other functionality to create process and ADMINISTER databases.

DBMS stands for Database Management System. A DBMS receives requests from applications and translates those requests into actions on a specific database. A DBMS processes SQL statements or uses other functionality to create process and administer databases.