Oracle SUBSTR & INSTR Functions

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Oracle SUBSTR & INSTR Functions

Version 11.1

SUBSTR (Substring) Built-in String Function SUBSTR(overload 1) SUBSTR( STR1VARCHAR2CHaraCTER SET ANY_CS, POSPLS_INTEGER,-- starting position LENPLS_INTEGER:= 2147483647) -- number of characters RETURNVARCHAR2CHaraCTER SET STR1%CHARSET; SUBSTR(overload 2) SUBSTR( STR1CLOBCHaraCTER SET ANY_CS, POSNUMBER,-- starting position LENNUMBER:= 2147483647) -- number of characters RETURNCLOBCHaraCTER SET STR1%CHARSET; Substring Beginning Of String SELECTSUBSTR(<value>,1,<number_of_characters>) FROMDUAL; SELECTSUBSTR('Take the first four characters',1,4) FirsT_FOUR FROMDUAL; Substring Middle Of String SELECTSUBSTR(<value>,<starting_position>,<number_of_characters>) FROMDUAL. SELECTSUBSTR('Take the first four characters',16,4) MIDDLE_FOUR FROMDUAL; Substring End of String SELECTSUBSTR(<value>,<starting_position>) FROMDUAL; SELECTSUBSTR('Take the first four characters',16) SIXTEEN_TO_END FROMDUAL; SELECTSUBSTR('Take the first four characters',-4) FINAL_FOUR FROMDUAL; Simplified Examples Examples in Oracle/PLsql of using thesubstr()function to extract a substring from a string: The general Syntax for theSUBSTR() function is: SUBSTR( source_string,start_position,[ length ] ) "source_string" is the original source_string that the substring will be taken from. "start_position" is the position in the source_string where you want to start extracting characters.The first position in the string is always '1',NOT '0',as in many other languages. "length" is an optional parameter that specifies how many characters to extract. If this parameter is not used,SUBSTR will return everything from the start_position to the end of the string. Notes: If the start_position is specified as "0",substr treats start_position as "1",that is,as the first position in the string. If the start_position is apositivenumber,then substr starts from thebeginningof the string. If the start_position is anegativenumber,then substr starts from theend of the string and counts backwards. If the length is a negative number,then substr will return a NULL value. Examples: substr('Dinner starts in one hour.',8,6) will return 'starts' substr('Dinner starts in one hour.',8) will return 'starts in one hour.' substr('Dinner starts in one hour.',6) will return 'Dinner' substr('Dinner starts in one hour.',-4,3) will return 'our' substr('Dinner starts in one hour.',-9,3) will return 'one' substr('Dinner starts in one hour.',2) will return 'on' This function works identically in Oracle 8i,Oracle 9i,Oracle 10g,and Oracle 11g. INSTR (Instring) Built-in String Function INSTR(overload 1) INSTR( STR1VARCHAR2CHaraCTER SET ANY_CS,-- test string STR2VARCHAR2CHaraCTER SET STR1%CHARSET,-- string to locate POSPLS_INTEGER:= 1,-- position NTHPOSITIVE:= 1) -- occurrence number RETURNPLS_INTEGER; INSTR(overload 2) INSTR( STR1CLOBCHaraCTER SET ANY_CS,-- test string STR2CLOBCHaraCTER SET STR1%CHARSET,-- string to locate POSINTEGER:= 1,-- position NTHPOSITIVE:= 1) -- occurrence number RETURNINTEGER; Instring For Matching First Value Found SELECTINSTR(<value>,<value_to_match>,<direction>,<instance> FROMDUAL; SELECTINSTR('Take the first four characters','a',1) FOUND_1 FROMDUAL; Instring If No Matching Second Value Found SELECTINSTR('Take the first four characters','a',2) FOUND_2 FROMDUAL; Instring For Multiple Characters SELECTINSTR('Take the first four characters','four',1) MCHARS FROMDUAL; Reverse Direction Search SELECTINSTR('Take the first four characters',-1,1) REV_SRCH FROMDUAL; Reverse Direction Search Second Match SELECTINSTR('Take the first four characters',2) REV_TWO FROMDUAL; String Parsing By Combining SUBSTR And INSTR Built-in String Functions List parsing first value Take up to the character before the first comma SELECTSUBSTR('abc,def,ghi',1,INSTR('abc,',1)-1) FROMDUAL; List parsing center value Take the value between the commas SELECTSUBSTR('abc,1)+1, INSTR('abc,2)-INSTR('abc,1)-1) FROMDUAL; List parsing last value Take the value after the last comma SELECTSUBSTR('abc,1)+1) FROMDUAL;