database and relative
  • Introduction
  • database
  • SQL
  • different kinds of Database
  • JDBC
  • oracle
  • MySQL
  • hibernate1
  • JavaPersistence:HibernateandJPAFundamentals0
  • keys
  • NoSQL DB
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  • 2. Clob vs Blob
  • 3. Truncate VS delete
  • 4. View vs Materalized View vs Table

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Last updated 5 years ago

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The CRUD cycle describes the elemental functions of a persistent database. CRUD stands for Create, Read, Update and Delete. (Retrieve may occasionally be substituted for Read.) These functions are also descriptive of the .

2. Clob vs Blob

LOB stands for large object, a stream of data stored in a database. Maximum capacity of a LOB is (4 gigabytes-1) bytes. In Oracle three kinds of LOB data type exist:

  • BLOB datetype stores unstructured binary large objects. BLOB objects can be thought of as bitstreams with no character set semantics.

  • The CLOB datatype stores single-byte and multibyte character data. Both fixed-width and variable-width character sets are supported, and both use the database character set.

  • The NCLOB datatype stores Unicode data.

3. Truncate VS delete

Truncate: removes all data from a table, typically bypassing a number of integrity enforcing mechanisms.

delete: delete existing records in a table.

4. View vs Materalized View vs Table

Materalized view: disk based and are updated periodidcally based upon the query definition.

view: virtual only and run the query definition each time they are accessed.

data life cycle