Oracle Key Concepts - Make Sure You Know All!
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Title: Oracle Database Administration Concepts &
Implementation Made Simple
ISBN: 0-9770739-0-4
Author: Asim Abbasi
Oracle Key Concepts - Make Sure You Know All!
61. PMON frees up the resources from a failed user process.
62. SMON is responsible for Instance recovery, if necessary.
63. Oracle running under Dedicated Server mode works the same as Shared
Server mode except that a new server process gets created to serve the
new logged in user.
64. Idle Time of Server process(es) will be more compared to Shared
Server environment.
65. For unlimited resources, always go with Dedicated Server Mode
otherwise stick with Shared Server Mode.
66. Understanding the difference between three terms: SQL, PL/SQL,
SQL*Plus
67. Horizontal goes the Records/Rows and vertical goes the
Fields/Columns.
68. We will write SQL commands in SQL*Plus software.
69. SELECT statement used for retrieval of information from Oracle
Database through Oracle Instance.
70. Oracle Instance receives these commands from connected users.
71. Operators help in filtering the number of records
72. Use parenthesis rather than utilizing “order of precedence” among
operators.
73. Single Row functions will result in same number of records as were
there in the output of the query without them e.g. TOCHAR, INITCAP etc.
74. Group functions will usually result in lesser number of records as
were there in the output of the query without them e.g., AVG, SUM, COUNT
etc.
75. Sole purpose of Join statement is to extract data from more than one
table based on some condition specified in the WHERE clause.
76. Primary/Foreign key relationship needs not to be present among
tables for making SELECT statement containing “joins” to run.
77. Only those records will be displayed from either of the two tables
where there is an exact match between the columns used in the WHERE
clause.
78. Primary & Foreign Key has nothing to do with Joins statements.
79. All different forms Joins are at the query level. The output exists
in the RAM and is volatile.
80. We can run Join queries on tables having Primary & Foreign Key
relationship established or not having this relationship.
Oracle Key Concepts - Make Sure You Know All!
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