Expert
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18-41. | Check the center.sf file on this book’s web page for a suggested function. |
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18-42. | Check the betwnstr.sql file on the book’s web page for a possible solution. |
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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; |
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18-44. | This function trims a pattern: /* Filename on web page: trim.sf ... |
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