Oracle PL/SQL Programming: A Developer's Workbook

Expert

Q:
18-41.	Check the center.sf file on this book’s web page for a suggested function.
Q:
18-42.	Check the betwnstr.sql file on the book’s web page for a possible solution.
Q:
18-43.	Here’s a suggested function: /* Filename on web page: betwnstr.sql */ CREATE OR REPLACE FUNCTION betwnstr ( str IN VARCHAR2, start_str IN VARCHAR2, end_str IN VARCHAR2 := NULL ) RETURN VARCHAR2 IS -- This function returns the characters in str that occur between -- the end of start_str and the beginning of end_str. -- -- If start_str does not occur in str or it occurs after end_str -- then NULL will be returned. BEGIN /* || If start_str does occur in str then perform a substring with the || following values : || || Start Point = location of start_str + length of start_str || Length = location of end_str - Start Point || || Not that if end_str is NULL the natural behaviour || of SUBSTR will return all || characters after start_str */ IF INSTR(str,start_str,1,1) > 0 THEN RETURN(SUBSTR(str,INSTR(str,start_str,1,1) + LENGTH(start_str), INSTR(str,end_str,1,1) - ( INSTR(str,start_str,1,1) + LENGTH(start_str)))); ELSE RETURN(str); END IF; END;
Q:
18-44.	This function trims a pattern: /* Filename on web page: trim.sf ...