Ritu

• Apr 25th, 2006

 

Purity level defines what type of datastructure function reads and modify.

Threre are 4 types of purity level

1)WNDS(Write No Database State)

2) RNDS(Read No Database State)

3)WNPS(Write No Package State)

2) RNPS(Read No Package State)

For package function , PRAGMA RESTRIC_REFRENCES is required.

Ex.    PRAGMA RESTRICT_REFRENCES(functionname,WNPS,RNPS)

pari

• Mar 14th, 2007

 

pragma_restrict_references is a compiler directive to check the purity level of functions used in packages.
The restriction on a function that it cannot do update, insert or delete when used in select statement does not stop it from compiling the err is given only at run time.
So the compiler directive provides hints to the compiler to avoid any such problem.
The four states are given above are absolutely correct 

asrafpa

 Profile Answers by asrafpa 

• Sep 26th, 2010

 

The function purity level defines what structures the function reads or modifies.

Following are the purity levels

1) WNDS - Writes No Database State i.e. Function does not modify any database tables (No DML)
2) RNDS - Reads No Database State i.e. Function does not read any tables (No select)
3) WNPS - Writes No Package State i.e. Function does not modify any packaged variables (packaged variables are variables declared in a package specification)
4) RNPS - Reads No Package State i.e. Function does not read any packaged variables

You can write the following in your package specification

CREATE PACKAGE loans AS
   FUNCTION credit_ok RETURN BOOLEAN;
   PRAGMA RESTRICT_REFERENCES (credit_ok, WNDS, RNPS);
END loans;
/

The package will execute depending on the purity level you have specified. You can give multiple purity levels too.