Oracle 10g SQL Fundamentals II--Les05

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Managing Data in Different Time Zones : 

Managing Data in Different Time Zones

Objectives : 

Objectives After completing this lesson, you should be able to use the following datetime functions: TZ_OFFSET FROM_TZ TO_TIMESTAMP TO_TIMESTAMP_TZ TO_YMINTERVAL TO_DSINTERVAL CURRENT_DATE CURRENT_TIMESTAMP LOCALTIMESTAMP DBTIMEZONE SESSIONTIMEZONE EXTRACT

Time Zones : 

Time Zones -08:00 The image represents the time for each time zone when Greenwich time is 12:00. -05:00 +02:00 +10:00 +07:00

TIME_ZONE Session Parameter : 

TIME_ZONE Session Parameter TIME_ZONE may be set to: An absolute offset Database time zone OS local time zone A named region ALTER SESSION SET TIME_ZONE = '-05:00'; ALTER SESSION SET TIME_ZONE = dbtimezone; ALTER SESSION SET TIME_ZONE = local; ALTER SESSION SET TIME_ZONE = 'America/New_York';

CURRENT_DATE, CURRENT_TIMESTAMP,and LOCALTIMESTAMP : 

CURRENT_DATE, CURRENT_TIMESTAMP,and LOCALTIMESTAMP CURRENT_DATE Returns the current date from the system Has a data type of DATE CURRENT_TIMESTAMP Returns the current timestamp from the system Has a data type of TIMESTAMP WITH TIME ZONE LOCALTIMESTAMP Returns the current timestamp from user session Has a data type of TIMESTAMP

CURRENT_DATE : 

CURRENT_DATE Display the current date and time in the session’s time zone. ALTER SESSION SET TIME_ZONE = '-8:0';SELECT SESSIONTIMEZONE, CURRENT_DATE FROM DUAL; ALTER SESSION SET TIME_ZONE = '-5:0'; SELECT SESSIONTIMEZONE, CURRENT_DATE FROM DUAL; ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';

CURRENT_TIMESTAMP : 

CURRENT_TIMESTAMP Display the current date and fractional time in the session’s time zone. ALTER SESSION SET TIME_ZONE = '-8:0'; SELECT SESSIONTIMEZONE, CURRENT_TIMESTAMP FROM DUAL; ALTER SESSION SET TIME_ZONE = '-5:0'; SELECT SESSIONTIMEZONE, CURRENT_TIMESTAMP FROM DUAL;

LOCALTIMESTAMP : 

LOCALTIMESTAMP Display the current date and time in the session’s time zone in a value of TIMESTAMP data type. LOCALTIMESTAMP returns a TIMESTAMP value, whereas CURRENT_TIMESTAMP returns a TIMESTAMP WITH TIME ZONE value. ALTER SESSION SET TIME_ZONE = '-5:0';SELECT CURRENT_TIMESTAMP, LOCALTIMESTAMP FROM DUAL; ALTER SESSION SET TIME_ZONE = '-8:0'; SELECT CURRENT_TIMESTAMP, LOCALTIMESTAMP FROM DUAL;

DBTIMEZONE and SESSIONTIMEZONE : 

DBTIMEZONE and SESSIONTIMEZONE Display the value of the database time zone. Display the value of the session’s time zone. SELECT DBTIMEZONE FROM DUAL; SELECT SESSIONTIMEZONE FROM DUAL;

TIMESTAMP Data Type : 

TIMESTAMP Data Type The TIMESTAMP data type is an extension of the DATE data type. It stores the year, month, and day of the DATE data type, plus hour, minute, and second values,as well as the fractional second value. Variations in TIMESTAMP are: TIMESTAMP[(fractional_seconds_precision)]_ TIMESTAMP [(fractional_seconds_precision)]_ WITH TIME ZONE TIMESTAMP [(fractional_seconds_precision)]_ WITH LOCAL TIME ZONE

TIMESTAMP Data Types : 

TIMESTAMP Data Types

TIMESTAMP Fields : 

TIMESTAMP Fields

Difference between DATE and TIMESTAMP : 

Difference between DATE and TIMESTAMP -- when hire_date is of type DATE SELECT hire_date FROM emp5; ALTER TABLE emp5 MODIFY hire_date TIMESTAMP; SELECT hire_date FROM emp5; B A … …

TIMESTAMP WITH TIME ZONE Data Type : 

TIMESTAMP WITH TIME ZONE Data Type TIMESTAMP WITH TIME ZONE is a variant of TIMESTAMP that includes a time zone displacement in its value. The time zone displacement is the difference,in hours and minutes, between local time and UTC. It is specified as: TIMESTAMP[(fractional_seconds_precision)] WITH TIME ZONE

TIMESTAMP WITH TIMEZONE: Example : 

TIMESTAMP WITH TIMEZONE: Example CREATE TABLE web_orders (ord_id number primary key, order_date TIMESTAMP WITH TIME ZONE); INSERT INTO web_orders values (ord_seq.nextval, current_date); SELECT * FROM web_orders;

TIMESTAMP WITH LOCAL TIMEZONE : 

TIMESTAMP WITH LOCAL TIMEZONE TIMESTAMP WITH LOCAL TIME ZONE is another variant of TIMESTAMP that includes a time zone displacement in its value. Data stored in the database is normalized to the database time zone. The time zone displacement is not stored as part of the column data. The Oracle database returns the data in the user’s local session time zone. The TIMESTAMP WITH LOCAL TIME ZONE data type is specified as follows: TIMESTAMP[(fractional_seconds_precision)] WITH LOCAL TIME ZONE

TIMESTAMP WITH LOCAL TIMEZONE: Example : 

TIMESTAMP WITH LOCAL TIMEZONE: Example CREATE TABLE shipping (delivery_time TIMESTAMP WITH LOCAL TIME ZONE); INSERT INTO shipping VALUES(current_timestamp + 2); SELECT * FROM shipping; ALTER SESSION SET TIME_ZONE = 'EUROPE/LONDON'; SELECT * FROM shipping;

INTERVAL Data Types : 

INTERVAL Data Types INTERVAL data types are used to store the difference between two datetime values. There are two classes of intervals: Year-month Day-time The precision of the interval is: The actual subset of fields that constitutes an interval Specified in the interval qualifier

INTERVAL Fields : 

INTERVAL Fields

INTERVAL YEAR TO MONTH Data Type : 

INTERVAL YEAR TO MONTH Data Type INTERVAL YEAR TO MONTH stores a period of time using the YEAR and MONTH datetime fields. For example: INTERVAL YEAR [(year_precision)] TO MONTH '312-2' assigned to INTERVAL YEAR(3) TO MONTH Indicates an interval of 312 years and 2 months '312-0' assigned to INTERVAL YEAR(3) TO MONTH Indicates 312 years and 0 months '0-3' assigned to INTERVAL YEAR TO MONTH Indicates an interval of 3 months

INTERVAL YEAR TO MONTH: Example : 

INTERVAL YEAR TO MONTH: Example CREATE TABLE warranty (prod_id number, warranty_time INTERVAL YEAR(3) TO MONTH); INSERT INTO warranty VALUES (123, INTERVAL '8' MONTH); INSERT INTO warranty VALUES (155, INTERVAL '200' YEAR(3)); INSERT INTO warranty VALUES (678, '200-11'); SELECT * FROM warranty;

INTERVAL DAY TO SECOND Data Type : 

INTERVAL DAY TO SECOND Data Type INTERVAL DAY TO SECOND (fractional_seconds_precision)stores a period of time in days, hours, minutes, and seconds. For example: INTERVAL DAY[(day_precision)] TO Second INTERVAL '6 03:30:16' DAY TO SECOND Indicates an interval of 6 days 3 hours 30 minutes and 16 seconds INTERVAL '6 00:00:00' DAY TO SECOND Indicates an interval of 6 days and 0 hours, 0 minutes and 0 seconds

INTERVAL DAY TO SECOND Data Type: Example : 

INTERVAL DAY TO SECOND Data Type: Example CREATE TABLE lab ( exp_id number, test_time INTERVAL DAY(2) TO SECOND); INSERT INTO lab VALUES (100012, '90 00:00:00'); INSERT INTO lab VALUES (56098, INTERVAL '6 03:30:16' DAY TO SECOND); SELECT * FROM lab;

EXTRACT : 

EXTRACT Display the YEAR component from the SYSDATE. Display the MONTH component from the HIRE_DATE for those employees whose MANAGER_ID is 100. SELECT EXTRACT (YEAR FROM SYSDATE) FROM DUAL; SELECT last_name, hire_date, EXTRACT (MONTH FROM HIRE_DATE) FROM employees WHERE manager_id = 100;

TZ_OFFSET : 

TZ_OFFSET Display the time zone offset for the time zone 'US/Eastern'. Display the time zone offset for the time zone 'Canada/Yukon'. Display the time zone offset for the time zone 'Europe/London'. SELECT TZ_OFFSET('US/Eastern') FROM DUAL; SELECT TZ_OFFSET('Canada/Yukon') FROM DUAL; SELECT TZ_OFFSET('Europe/London') FROM DUAL;

Notes Only : 

Notes Only

TIMESTAMP Conversion Using FROM_TZ : 

TIMESTAMP Conversion Using FROM_TZ Display the TIMESTAMP value '2000-03-28 08:00:00' as a TIMESTAMP WITH TIME ZONE value. Display the TIMESTAMP value '2000-03-28 08:00:00' as a TIMESTAMP WITH TIME ZONE value for the time zone region 'Australia/North'. SELECT FROM_TZ(TIMESTAMP '2000-03-28 08:00:00','3:00') FROM DUAL; SELECT FROM_TZ(TIMESTAMP '2000-03-28 08:00:00', 'Australia/North') FROM DUAL;

Converting to TIMESTAMP Using TO_TIMESTAMP and TO_TIMESTAMP_TZ : 

SELECT TO_TIMESTAMP_TZ('1999-12-01 11:00:00 -8:00', 'YYYY-MM-DD HH:MI:SS TZH:TZM')FROM DUAL; Converting to TIMESTAMP Using TO_TIMESTAMP and TO_TIMESTAMP_TZ Display the character string '2000-12-01 11:00:00'as a TIMESTAMP value. Display the character string '1999-12-01 11:00:00 -8:00' as a TIMESTAMP WITH TIME ZONE value. SELECT TO_TIMESTAMP ('2000-12-01 11:00:00', 'YYYY-MM-DD HH:MI:SS') FROM DUAL;

Time Interval Conversion with TO_YMINTERVAL : 

Time Interval Conversion with TO_YMINTERVAL Display a date that is one year, two months after the hire date for the employees working in the department with the DEPARTMENT_ID 20. SELECT hire_date, hire_date + TO_YMINTERVAL('01-02') AS HIRE_DATE_YMININTERVAL FROM employeesWHERE department_id = 20;

Using TO_DSINTERVAL: Example : 

Using TO_DSINTERVAL: Example TO_DSINTERVAL: Converts a character string to an INTERVAL DAY TO SECOND data type SELECT last_name, TO_CHAR(hire_date, 'mm-dd-yy:hh:mi:ss') hire_date, TO_CHAR(hire_date + TO_DSINTERVAL('100 10:00:00'), 'mm-dd-yy:hh:mi:ss') hiredate2 FROM employees; …

Daylight Saving Time : 

Daylight Saving Time First Sunday in April Time jumps from 01:59:59 a.m. to 03:00:00 a.m. Values from 02:00:00 a.m. to 02:59:59 a.m. are not valid. Last Sunday in October Time jumps from 02:00:00 a.m. to 01:00:01 a.m. Values from 01:00:01 a.m. to 02:00:00 a.m. are ambiguous because they are visited twice.

Notes Only : 

Notes Only

Summary : 

Summary In this lesson, you should have learned how to use the following functions: TZ_OFFSET FROM_TZ TO_TIMESTAMP TO_TIMESTAMP_TZ TO_YMINTERVAL CURRENT_DATE CURRENT_TIMESTAMP LOCALTIMESTAMP DBTIMEZONE SESSIONTIMEZONE EXTRACT

Practice 5: Overview : 

Practice 5: Overview This practice covers using the datetime functions.

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