Max Data Code: 09. TCL COMMANDS And LITERALS

TCL COMMANDS:

TCL: Transaction control language.

Commit:

ü It makes temporary transaction permanent

ü It empties the buffer memory area

ü A SCN number get generated for each of the transaction (or) for every commit

ü It makes temporary piece of work as permanent

Roll Back

ü It cancels the transaction or piece of work

ü It also empties the buffer memory area permanently

ü Partial roll backing is also possible with the help of save point.

Save Point:

ü It is a mark which specifies teset of statements or piece of work.

Note:

ü It is not possible to nest the transactions directly but by using some other means (program autonomous transaction) it is possible.

ü A DDL command also makes the above temporary work permanent while becoming permanent.

LITERALS

Literals are predefined values or constants identified by oracle server

Types of literals:

1) Number literals:

USAGE: 1, 10,

EG: SELECT 1 FROM DUAL;

2) String literals: anything enclosed in quotes is considered string:

USAGE: ‘A’,’10’,’13-SEP-13’

EG: SELECT ‘A’,’10’,’13-SEP-13’ FROM DUAL;

3) Date literals:

USAGE: DATE ‘YYYY-MM-DD’

EG: SELECT DATE ’2013-09-13’ FROM DUAL;

EG: SELECT DATE ’2013-09-13’+1 FROM DUAL

4) Timestamp literal:

USAGE: TIMESTAMP ‘YYYY-MM-DD HH: MI: SS.FF’

EG: SELECT TIMESTAMP ‘2013-06-10 10:10:10.10 FROM DUAL;

5) Timestamp with time zone literal:

USAGE: TIMESTAMP ‘YYYY-MM-DD HH: MI: SS.FF +TZH: TZM’;

EG: SELECT TIMESTAMP '2012-09-10 10:10:10.000 +05:30' FROM DUAL;

6) Interval Literals:

a) Interval year to month literals:

USAGE: INTERVAL ‘YY-MM’ YEAR TO MONTH;

EG: SELECT INTERVAL '10-10' YEAR TO MONTH FROM DUAL;

b) Interval day to second:

USAGE: INTERVAL ‘DD HH: MI: SS.FF DAY TO SECOND;

EG: SELECT INTERVAL '10 10:10:10.1000' DAY TO SECOND FROM

DUAL;

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