Oracle PL/SQL Quick Reference
PL/SQL Block Structure
DECLARE --Optional --Variables, Cursors, User-defined exceptions BEGIN --Mandatory --SQL statements --PL/SQL statements EXCEPTION --Optional --Actions to perform when errors occur END; --Mandatory Read more...
consideration when writing an SQL statement is that it returns a correct result. The second is that it be the most efficient for a given situation. You can use many different SQL statements to achieve the same result. It is often the case that only one statement will be the most efficient choice in a given situation.
Remember that processing SQL is a sequence of Parse (syntax check and object resolution), Execution (required reads and writes), and Fetch (row results retrieved, listed, sorted, and returned). SQL “tuning” consists, quite simply, of reducing one or more of them.
Note: generally Parse is the greatest time and resource hog. Parse overhead can be minimized by the use of Procedures, Functions, Packages, Views, etc.
Inadequate performance can have a significant cost impact on your business. A poor performing system and application can result in customer dissatisfaction, reduced productivity, and high costs. It is absolutely critical that the system’s performance is operating at its peak levels.
Following are some general tips that often increase SQL statement efficiency. Being general they may not apply to a particular scenario. Read more…
SQL*Plus is a command-line tool that provides access to the Oracle RDBMS.
SQL*Plus enables you to:
SQL*Plus is available on several platforms. In addition, it has a web-based user
interface, iSQL*Plus.
SQL*Plus is a client terminal software allowing users to interact with Oracle server to manipulate data and data structures. Users type in SQL statements in SQL*Plus that send statements to Oracle server. Oracle server then validates and executes the statements on its databases. The query results are returned to SQL*Plus and displayed to the user. Besides sending SQL statements to the server, SQL*Plus also saves them into a local buffer and allow users to view and change the statements. The following figure illustrates the process. Read more…