[29/07/2008 21:33:45 ]

L1. Retrieving data using SELECT statement
1.Tips for writing SQL statement
    a.Clauses are usually placed on separate lines.
    b.In SQL Developer, SQL statements can optionally be terminated by a semicolon. Semicolons are required when you execute multiple SQL statements.
    c.In SQL*Plus, you are required to end each SQL statement with a semicolon.
    
2.Arithmetic expressions in the SELECT statement
    Example:SELECT last_name, salary, 12*(salary+100) FROM employees;
   
3.Column aliases
    Example:SELECT last_name "Name" , salary*12 "Annual Salary" FROM employees;
   
4.Use of concatenation operator, literal character strings, alternative quote operator, and the DISTINCT keyword
    a.Concatenation operator(||)
      Example:SELECT last_name||job_id AS "Employees" FROM employees;
    b.Literal Character Strings(')
      Example:SELECT last_name ||' is a '||job_id AS "Employee Details" FROM employees;
    c.Alternative Quote (q) Operator
      Example:SELECT department_name || ' Department' || q'['s Manager Id: ]' || manager_id AS "Department and Manager" FROM departments;
    d.Duplicate Rows
      Example:SELECT DISTINCT department_id FROM employees;