Answer / saraswathi muthuraman

TO apply business rule we are using Constraints and trigger.

If we have any computation and validation over the
calculated value we have choose "trigger".


Direct validation like the column should not contain null
values then you can choose Constraints.

Constraints : NOT NULL,UNIQUE,PRIMARY KEY,CHECK,REFERENCE

Trigger effected only those row after which trigger applied
but constraint effected all row of table .

Answer / mohanbabu

Constraints are used to limit the type of data that can go
into a table.
Constraints can be specified when a table is created or
after the table is created.

A trigger is a fragment of code that you tell Oracle to run
before or after table is modified.

Answer / shekar

Triggers: It checks the condition and Performs some action
eg: it checks and fires before or after insert or update
or delete

Constriants: it checks the condition
eg: suppose NotNull constraint.It jst doesn't allow null
values.

Answer / manoranan sethy

Constraints are restrict the invalid data before invoke into the database whereas trigger restrict the invalid transaction.

How to convert lowercase letters to uppercase and uppercase letters to lowercase in a string. (ex, AbcdEfG should convert as aBCDeFg)

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Hi Guys, I have a situation where I need to access the column values from rowtype variable. However, the column names are dynamic. below is sample code: declare Cursor c1 is select * from emp; Cursor c2 is select column_name from xyztable; v_c2 c2%rowtype; v_str varchar2 v_value varchar2(200); begin for rec in c1 loop open c2;---this cursor has column names like EMPLOYEE_ID, FIRST_NAME, LAST_NAME etc. loop fetch c2 into v_c2; exit when c2%notfound; /* now lets say i want to access value of LAST_NAME from cursor c1, so I am writing below code, however it does not work as expected */ v_str:= 'rec.'|| v_c2.column_name; -- this will give me string like "rec.EMPLOYEE_ID" v_value:=v_str; end loop; end loop; end; / Plz help ASAP.Thanks.

2 Answers  

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