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Introduction

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GENERAL

  • SQL is 4GL
  • "" can be used to make case sensitive for column names
  • Schema is like a folder in a database. It is objects that can be owned by a user account

NORMAL FORM

  • 1NF --> No repeating groups 2-dimensional
  • 2NF --> Primary key that is not composite
  • 3NF --> No data that does not provide the intend of primary key
  • Boyce-Codd NF --> Remove certain rare logical inconsistencies
  • 4NF --> Every multivalued dependency is dependent on a super key
  • 5NF --> Every join dependency is a result of the candidate keys

NAMESPACE

  • USER, ROLES, PUBLIC SYNONYMNS System
  • TABLE, VIEW, SEQUENCE, PRIVATE SYNONYMNS, USER DEFINED TYPES Schema
  • INDEX Schema
  • CONSTRAINT Schema

DATATYPES

  • CHAR(n) Retrieved with spaces
  • VARCHAR2(n)
  • NUMBER(n, m) n is precision - total number in either side after scaling m is scale - total number on right side of decimal point. If a value has more significant digits to the left of the decimal place than are specified in the format, then pound signs (#) replace the value. If a positive value is extremely large and cannot be represented in the specified format, then the infinity sign (~) replaces the value. Likewise, if a negative value is extremely small and cannot be represented by the specified format, then the negative infinity sign replaces the value (-~)
  • DATE NLS_DATE_FORMAT NLS_TERRITORY
  • TIMESTAMP(n 1-9/6)
  • TIMESTAMP(n 1-9/6) WITH TIMEZONE
  • TIMESTAMP(n 1-9/6) WITH LOCAL TIMEZONE
  • INTERVAL YEAR(n 1-9/2) TO MONTH
  • INTERVAL DAY(n1 1-9/2) TO SECOND(n2 1-9/6)
  • BLOB
  • CLOB
  • NCLOB (UTF)

IT Notes

by VinodSebastian



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