oralce字符串函数

set serveroutput on

DECLARE
c1CLOB:=TO_CLOB('Dan ');
c2CLOB:=TO_CLOB('Morgan');
c3CLOB;
BEGIN
SELECTCONCAT(c1,c2)
INTOc3
FROM DUAL;

dbms_output.put_line(c3);
END;
/

CONVERT

Converts From One Character Set To Another

CONVERT(<character>,<destination_character_set>,
<source_character_set>)

SELECTCONVERT('Ä Ê Í Õ Ø A B C D E','US7ASCII','WE8ISO8859P1')
FROM DUAL;

DUMP

Returns aVARCHAR2value containing the datatype code,length in bytes,and internal representation of a value

DUMP(<value> [,<return_format>[,<start_position>[,<length>]]])

8	Octal
10	Decimal
16	Hexidecimal
17	Single Characters
1008	octal notation with the character set name
1010	decimal notation with the character set name
1016	hexadecimal notation with the character set name
1017	single characters with the character set name

set linesize 121
col dmp format a50

SELECTtable_name,DUMP(table_name) DMPFROMuser_tables;

SELECTtable_name,DUMP(table_name,16) DMPFROMuser_tables;

SELECTtable_name,16,7,4) DMPFROMuser_tables;

INSTR

See links at page bottom

INSTRB

Location of a string,within another string,in bytes

INSTRB(
STR1VARCHAR2CHaraCTER SET ANY_CS,-- test string
STR2VARCHAR2CHaraCTER SET STR1%CHARSET,-- string to locate
POSPLS_INTEGER:= 1,-- position
NTHPOSITIVE:= 1) -- occurrence number
RETURN PLS_INTEGER;

SELECTINSTRB('Dan Morgan',' ',1,1)FROM DUAL;

INSTRC

Location of a string,in Unicode complete characters

INSTRC(
STR1VARCHAR2CHaraCTER SET ANY_CS,-- position
NTHPOSITIVE:= 1) -- occurrence number
RETURN PLS_INTEGER;

SELECTINSTRC('Dan Morgan',1)FROM DUAL;

INSTR2

Location of a string,in UCS2 code points

INSTR2(
STR1VARCHAR2CHaraCTER SET ANY_CS,-- position
NTHPOSITIVE:= 1) -- occurrence number
RETURN PLS_INTEGER;

SELECTINSTR2('Dan Morgan',1)FROM DUAL;

INSTR4

Location of a string,in UCS4 code points

INSTR4(
STR1VARCHAR2CHaraCTER SET ANY_CS,-- position
NTHPOSITIVE:= 1) -- occurrence number
RETURN PLS_INTEGER;

SELECTINSTR4('Dan Morgan',1)FROM DUAL;

LENGTH

String Length

LENGTH(<string_or_column>)

SELECTLENGTH('Dan Morgan')FROM DUAL;

LENGTHB

Returns length in bytes

LENGTHB(<char_varchar2_or_clob_value>)

SELECTtable_name,LENGTHB(table_name)FROMuser_tables;

Note:Additional forms of LENGTH (LENGTHC,LENGTH2,and LENGTH4) are also available.

LPAD

Left Pad

Overload 1

LPAD(
str1VARCHAR2CHaraCTER SET ANY_CS,
lenPLS_INTEGER,
PADVARCHAR2CHaraCTER SET STR1%CHARSET)
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

SELECTLPAD('Dan Morgan',25,'x')FROM DUAL;

Overload 2

LPAD(
str1VARCHAR2CHaraCTER SET ANY_CS,
lenPLS_INTEGER)
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

SELECTLPAD('Dan Morgan',25)FROM DUAL;

Overload 3

LPAD(
str1CLOBCHaraCTER SET ANY_CS,
lenNUMBER,
PADCLOBCHaraCTER SET STR1%CHARSET)
RETURN CLOBCHaraCTER SET STR1%CHARSET;

TBD

Overload 4

LPAD(
str1CLOBCHaraCTER SET ANY_CS,
len INTEGER)
RETURN CLOBCHaraCTER SET STR1%CHARSET;

TBD

LTRIM

Left Trim

Overload 1

LTRIM(
str1VARCHAR2CHaraCTER SET ANY_CS := ' ',
tsetVARCHAR2CHaraCTER SET STR1%CHARSET)
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

SELECT'->' ||LTRIM(' Dan Morgan ') || '<-'FROM DUAL;

Overload 2

LTRIM(
STR1VARCHAR2CHaraCTER SET ANY_CS := ' ')
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

SELECT'->' ||LTRIM('xxx Dan Morgan ') || '<-'FROM DUAL;

SELECT'->' ||LTRIM('xxxDan Morgan ','x') || '<-'FROM DUAL;

MAX

The Maximum String based on the current sort parameter

MAX(<character_string>)

SELECTMAX(table_name)
FROMuser_tables;

MIN

The Minimum String based on the current sort parameter

MIN(<character_string>)

SELECTMIN(table_name)
FROMuser_tables;

NLSSORT

Returns the string of bytes used to sort a string.

The string returned is of RAW data type

NLSSORT(<column_name>,'NLS_SORT= <NLS Parameter>);

CREATE TABLEtest (nameVARCHAR2(15));
INSERT INTOtestVALUES('Gaardiner');
INSERT INTOtestVALUES('Gaberd');
INSERT INTOtestVALUES('GÂberd');
COMMIT;

SELECT*FROMtestORDER BYname;

SELECT*FROMtest
ORDER BYNLSSORT(name,'NLS_SORT= XDanish');

SELECT*FROMtest
ORDER BYNLSSORT(name,'NLS_SORT= BINARY_CI');

Quote Delimiters

q used to define a quote delimiter for PL/sql

q'<delimiter><string><delimiter>';

set serveroutput on

DECLARE
s1VARCHAR2(20);
s2VARCHAR2(20);
s3VARCHAR2(20);
BEGIN
s1 :=q'[Isn't this cool]';
s2 :=q'"Isn't this cool"';
s3 :=q'|Isn't this cool|';

dbms_output.put_line(s1);
dbms_output.put_line(s2);
dbms_output.put_line(s3);
END;
/

REPLACE

See links at page bottom

REVERSE

Reverse

REVERSE(<string_or_column>)

SELECTREVERSE('Dan Morgan')FROM DUAL;

SELECT DUMP('Dan Morgan')FROM DUAL;
SELECT DUMP(REVERSE('Dan Morgan'))FROM DUAL;

RPAD

Right Pad

Overload 1

RPAD(str1VARCHAR2CHaraCTER SET ANY_CS,lenPLS_INTEGER,
padVARCHAR2CHaraCTER SET STR1%CHARSET)
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

SELECTRPAD('Dan Morgan','x')FROM DUAL;

Overload 2

RPAD(str1VARCHAR2CHaraCTER SET ANY_CS,lenPLS_INTEGER)
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

SELECTRPAD('Dan Morgan',25) ||'<-'FROM DUAL;

RTRIM

Right Trim

Overload 1

RTRIM(
str1VARCHAR2CHaraCTER SET ANY_CS := ' ',
tsetVARCHAR2CHaraCTER SET STR1%CHARSET)
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

SELECT'->' ||RTRIM(' Dan Morganxxx') || '<-'FROM DUAL;
SELECT'->' ||RTRIM(' Dan Morganxxx','xxx') || '<-'FROM DUAL;

Overload 2

RTRIM(
str1VARCHAR2CHaraCTER SET ANY_CS := ' ')
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

SELECT'->' ||RTRIM(' Dan Morgan ') || '<-'FROM DUAL;

SOUNDEX

Returns Character String Containing The Phonetic Representation Of Another String

Rules:

Retain the first letter of the string and remove all other occurrences of the following letters: a,e,h,i,o,u,w,y
Assign numbers to the remaining letters (after the first) as
follows:
b,f,p,v = 1
c,g,j,k,q,s,x,z = 2
d,t = 3
l = 4
m,n = 5
r = 6
If two or more letters with the same number were adjacent in the original name (before step 1),or adjacent except for any intervening h and w,then omit all but the first.
Return the first four bytes padded with 0.

SOUNDEX(chVARCHAR2CHaraCTER SET ANY_CS)
RETURN VARCHAR2CHaraCTER SET ch%CHARSET;

CREATE TABLEtest (
namecolVARCHAR2(15));

INSERT INTOtest (namecol)VALUES('Smith');
INSERT INTOtest (namecol)VALUES('Smyth');
INSERT INTOtest (namecol)VALUES('Smythe');
INSERT INTOtest (namecol)VALUES('Smither');
INSERT INTOtest (namecol)VALUES('Smidt');
INSERT INTOtest (namecol)VALUES('Smick');
INSERT INTOtest (namecol)VALUES('Smiff');
COMMIT;

SELECTnamecol,SOUNDEX(namecol)FROMtest;
-- Thanks Frank van Bortel for the idea for the above

SELECT*
FROMtest
WHERESOUNDEX(namecol) =SOUNDEX('SMITH');

SUBSTR

See links at page bottom

SUBSTRB

Returns a substring countingbytesrather thancharacters

SUBSTRB(
STR1VARCHAR2CHaraCTER SET ANY_CS,
POSPLS_INTEGER,-- starting position
LENPLS_INTEGER:= 2147483647) -- number of characters
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

See Demos on theSubstringPage

SUBSTRC

Returns a substring within another string,using Unicode code points

SUBSTRC(
STR1VARCHAR2CHaraCTER SET ANY_CS,-- starting position
LENPLS_INTEGER:= 2147483647) -- number of characters
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

See Demos on theSubstringPage

SUBSTR2

Returns a substring within another string,using UCS2 code points

SUBSTR2(
STR1VARCHAR2CHaraCTER SET ANY_CS,-- starting position
LENPLS_INTEGER:= 2147483647) -- number of characters
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

See Demos on theSubstringPage

SUBSTR4

Returns a substring within another string,using UCS4 code points

SUBSTR4(
STR1VARCHAR2CHaraCTER SET ANY_CS,-- starting position
LENPLS_INTEGER:= 2147483647) -- number of characters
RETURN VARCHAR2CHaraCTER SET STR1%CHARSET;

See Demos on theSubstringPage

TRANSLATE

See links at page bottom

TREAT

Changes The Declared Type Of An Expression

TREAT(<expression> AS REF schema.type))

SELECTname,TREAT(VALUE(p)ASemployee_t).salary SALARY
FROMpersons p;

TRIM (variations are LTRIM and RTRIM)

Trim Spaces

TRIM(<string_or_column>)

SELECT' Dan Morgan 'FROM DUAL;

SELECTTRIM(' Dan Morgan ')FROM DUAL;

Trim Other Characters