Les002

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Copyright © Oracle Corporation, 2001. All rights reserved.
ORDER BY Clause
•
Sort rows with the ORDER BY clause
– – ASC: ascending order, default DESC: descending order
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Copyright © Oracle Corporation, 2001. All rights reserved.
Using the NULL Conditions
Test for nulls with the IS NULL operator.
SELECT last_name, manager_id FROM employees WHERE manager_id IS NULL;
Operator = > >= < <= <> Meaning Equal to Greater than Greater than or equal to Less than Less than or equal to Not equal to
2-7
Copyright © Oracle Corporation, 2001. All rights reserved.
Using Comparison Conditions
SELECT last_name, salary FROM employees WHERE salary <= 3000;
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Copyright © Oracle Corporation, 2001. All rights reserved.
• Limit the rows retrieved by a query • Sort the rows retrieved by a query
2-2
Copyright © Oracle Corporation, 2001. All rights reserved.
Limiting Rows Using a Selection
Character Strings and Dates
• • •
Character strings and date values are enclosed in single quotation marks. Character values are case sensitive, and date values are format sensitive. The default date format is DD-MON-RR.
NOT
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Copyright © Oracle Corporation, 2001. All rights reserved.
Using the AND Operator
AND requires both conditions to be true.
SELECT FROM WHERE AND employee_id, last_name, job_id, salary employees salary >=10000 job_id LIKE '%MAN%';
– % denotes zero or many characters. – _ denotes one character.
SELECT FROM WHERE
first_name employees first_name LIKE 'S%';
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Copyright © Oracle Corporation, 2001. All rights reserved.
2-16
Copyright © Oracle Corporation, 2001. All rights reserved.
Using the OR Operator
OR requires either condition to be true.
SELECT FROM WHERE OR employee_id, last_name, job_id, salary employees salary >= 10000 job_id LIKE '%MAN%';
Other Comparison Conditions
Operator BETWEEN ...AND... IN(set) LIKE IS NULL Meaning Between two values (inclusive),
Match any of a list of values Match a character pattern Is a null value
Using the WHERE Clause
SELECT employee_id, last_name, job_id, department_id FROM employees WHERE department_id = 90 ;
2-5
Copyright © Oracle Corporation, 2001. All rights reserved.
2-18
Copyright © Oracle Corporation, 2001. All rights reserved.
Rules of Precedence
Order Evaluated 1 2 3 4 5 6 7 8
Operator Arithmetic operators Concatenation operator Comparison conditions IS [NOT] NULL, LIKE, [NOT] IN [NOT] BETWEEN NOT logical condition AND logical condition OR logical condition
•
The ORDER BY clause comes last in the SELECT statement.
last_name, job_id, salary employees job_id = 'SA_REP' job_id = 'AD_PRES' salary > 15000;
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Copyright © Oracle Corporation, 2001. All rights reserved.
SELECT last_name, job_id, department_id FROM employees WHERE last_name = 'Whalen';
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Copyright © Oracle Corporation, 2001. All rights reserved.
Comparison Conditions
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Copyright © Oracle Corporation, 2001. All rights reserved.
Using the BETWEEN Condition
Use the BETWEEN condition to display rows based on a range of values.
Rules of Precedence
Use parentheses to force priority.
SELECT FROM WHERE OR AND last_name, job_id, salary employees (job_id = 'SA_REP' job_id = 'AD_PRES') salary > 15000;
Override rules of precedence by using parentheses.
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Copyright © Oracle Corporation, 2001. All rights reserved.
Rules of Precedence
SELECT FROM WHERE OR AND
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Copyright © Oracle Corporation, 2001. All rights reserved.
Using the NOT Operator
SELECT last_name, job_id FROM employees WHERE job_id NOT IN ('IT_PROG', 'ST_CLERK', 'SA_REP');
SELECT last_name, salary FROM employees WHERE salary BETWEEN 2500 AND 3500;
Lower limit
Upper limit
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Copyright © Oracle Corporation, 2001. All rights reserved.
Using the LIKE Condition
•
You can combine pattern-matching characters.
SELECT last_name FROM employees WHERE last_name LIKE '_o%';
•
You can use the ESCAPE identifier to search for the actual % and _ symbols.
Restricting and Sorting Data
Copyright © Oracle Corporation, 2001. All rights reserved.
Objectives