Oracle Magazine, July/August 2017
Database Application Developer and DBA BEYOND SQL 101 ORACLE MAGAZINE JULY AUGUST 2017 119 old 3 where table_ name v_ table new 3 where table_ name EMPLOYEE TABLE_ NAME INDEX_ NAME COLUMN_ NAME COLUMN_ POSITION EMPLOYEE EMP_ HIRE_ DATE_ I HIRE_ DATE 1 EMPLOYEE DEP_ WAGE_ INCREASE_ I DEPARTMENT_ ID 1 EMPLOYEE DEP_ WAGE_ INCREASE_ I WAGE_ INCREASE_ WORTHINESS 2 EMPLOYEE EMPLOYEE_ PK EMPLOYEE_ ID 1 EMPLOYEE EMP_ DEPT_ FK DEPARTMENT_ ID 1 EMPLOYEE EMPLOYEE_ WAGE_ INC_ WORTH_ BMI WAGE_ INCREASE_ WORTHINESS 1 6 rows selected If you want to reset the value of your substitution variable when using double ampersand notation delete the current value with the UNDEFINE SQL Plus command For example to delete the current value of the v_ table substitution variable in SQL Plus use the command undefine v_ table CONCLUSION This article introduced you to the data dictionary from the USER_ ALL_ and DBA_ static data dictionary views to the dynamic performance views the V tables You saw database scripts combine multiple statements in a sequence into one file You learned what a substitution variable is and how it can help in reducing SQL state
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