NOT NULL Constraint - Disallows Nulls in a table's column.UNIQUE Constraint - Disallows duplicate values in a column or set of columns.PRIMARY KEY Constraint - Disallows duplicate values and Nulls in a column or set of columns.FOREIGN KEY Constrain - Require each value in a column or set of columns match a value in a related table's UNIQUE or PRIMARY KEY.CHECK Constraint - Disallows values that do...

Schema objects are the logical structures that directly refer to the database's data. Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and database links.

Yes.

Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.Hide data complexity.Simplify commands for the user.Present the data in a different perspective from that of the base table.Store complex queries.

There are two types of Synonyms Private and Public.

A Private Synonyms can be accessed only by the owner.

Public synonyms can be accessed by any user on the database.

An Index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.

A Cluster with an index on the Cluster Key.

Hash clusters are better choice when a table is often queried with equality queries. For such queries the specified cluster key value is hashed. The resulting hash key value points directly to the area on disk that stores the specified rows.

Private Database Link, Public Database Link & Network Database Link.

Network database link is created and managed by a network domain service. A network database link can be used when any user of any database in the network specifies a global object name in a SQL statement or object definition.

If a foreign key reference a parent key of the same table is called self-referential integrity constraint.

samiksc

 Profile Answers by samiksc Questions by samiksc

• Jan 19th, 2006

Self referential integrity constraint refers to two columns related by referential integrity which belong to the same table.For example ManagerId column in employees table is a foreign key which refers to EmployeeId in the same table.

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The condition must be a Boolean expression evaluated using the values in the row being inserted or updated and can't contain sub queries, sequence, the SYSDATE,UID,USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.

fancyoracle

 Profile Answers by fancyoracle Questions by fancyoracle

• Aug 16th, 2007

A check constraint allows you to specify a condition on each row in a table. Note: A check constraint can NOT be defined on a VIEW. The check constraint defined on a table must refer to only columns i...

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A synonym is an alias for a table, view, sequence or program unit.

thumatinagaraju

 Profile Answers by thumatinagaraju Questions by thumatinagaraju

• Oct 24th, 2006

Ya synonym is used to rename or to create alias for the data base object ..

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Clusters are groups of one or more tables physically stores together to share common columns and are often used together.

partho sarathi konar

• Oct 1st, 2006

Clusters are groups of one or more tables physically stored together because they share common columns and are often used together. This improves disk access time.The related columns of the tables in ...

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A row is stored in a hash cluster based on the result of applying a hash function to the row's cluster key value. All rows with the same hash key value are stores together on disk.

partho sarathi konar

• Oct 1st, 2006

Hash Clusters cluster table data in a manner similar to normal, index clusters. To find or store a row in a hash cluster, Oracle applies a hash function to the row's cluster key value. The resulting h...

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In Circumstances, all of the data for a row in a table may not be able to fit in the same data block. When this occurs , the data for the row is stored in a chain of data block (one or more) reserved for that segment.

feroz

• Aug 29th, 2006

If a row is too large to fit into a single database block row chaining happens. For example, if you use a 4KB blocksize for your database, and you need to insert a row of 8KB into it, Oracle will...

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An integrity constraint is a declarative way to define a business rule for a column of a table.

simakas

• Oct 5th, 2007

Special requirements for table data:1) allow NULL value2) uniqueness of value3) primary key4) foreign key5) special value size/text/length etc requirementsAll information is stored in Data Dictionary.

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