Oracle中INSTR和SUBSTR的用法

Oracle中INSTR的用法：

INSTR方法的格式为

INSTR(源字符串, 要查找的字符串, 从第几个字符开始, 要找到第几个匹配的序号)

返回找到的位置，如果找不到则返回0.

例如：INSTR('CORPORATE FLOOR','OR', 3, 2)中，源字符串为'CORPORATE FLOOR',

在字符串中查找'OR'，从第三个字符位置开始查找"OR"，取第三个字后第2个匹配项的位置。

默认查找顺序为从左到右。当起始位置为负数的时候，从右边开始查找。

所以SELECT INSTR('CORPORATE FLOOR', 'OR', -1, 1) "aaa" FROM

DUAL的显示结果是

Instring

——————

14

oracle的substr函数的用法：

取得字符串中指定起始位置和长度的字符串 substr( string, start_position, [ length ] )

如:

substr('This is a test', 6,

2) would return 'is'

substr('This is a test',

6) would return 'is a test'

substr('TechOnTheNet', -3,

3) would return 'Net'

substr('TechOnTheNet', -6,

3) would return 'The'

select substr('Thisisatest', -4, 2) value from dual

综合应用：

SELECT INSTR('CORPORATE FLOOR', 'OR', -1, 1) "Instring" FROM

DUAL

--INSTR(源字符串, 目标字符串, 起始位置, 匹配序号)

SELECT INSTR('CORPORATE FLOOR','OR', 3, 2) "Instring" FROM DUAL

SELECT INSTR('32.8,63.5',',', 1, 1) "Instring" FROM DUAL

SELECT SUBSTR('32.8,63.5',INSTR('32.8,63.5',',', 1, 1)+1)

"INSTRING" FROM DUAL

SELECT SUBSTR('32.8,63.5',1,INSTR('32.8,63.5',',', 1, 1)-1)

"INSTRING" FROM DUAL

-- CREATED ON 2008-9-26 BY ADMINISTRATOR

DECLARE

-- LOCAL VARIABLES HERE

T VARCHAR2(2000);

S VARCHAR2(2000);

NUM INTEGER;

I INTEGER;

POS INTEGER;

BEGIN

-- TEST STATEMENTS HERE

T := '12.3,23.0;45.6,54.2;32.8,63.5;';

SELECT LENGTH(T) - LENGTH(REPLACE(T, ';', ''))

INTO NUM FROM DUAL;

DBMS_OUTPUT.PUT_LINE('NUM:' || NUM);

POS := 0;

FOR I IN 1 .. NUM LOOP

DBMS_OUTPUT.PUT_LINE('I:' || I);

DBMS_OUTPUT.PUT_LINE('POS:' || POS);

DBMS_OUTPUT.PUT_LINE('==:' || INSTR(T, ';', 1, I));

DBMS_OUTPUT.PUT_LINE('INSTR:' || SUBSTR(T, POS + 1, INSTR(T, ';',

1, I) - 1));

POS :=

INSTR(T, ';', 1, I);

END LOOP;

END;

-- Created on 2008-9-26 by ADMINISTRATOR

declare

-- Local variables here

i integer;

T VARCHAR2(2000);

S VARCHAR2(2000);

begin

-- Test statements here

--历史状态

T := '12.3,23.0;45.6,54.2;32.8,63.5;';

IF (T IS NOT NULL) AND (LENGTH(T)

> 0) THEN

--T := T ||

',';

WHILE

LENGTH(T) > 0 LOOP

--ISTATUSID := 0;

S := TRIM(SUBSTR(T, 1, INSTR(T, ';') - 1));

IF LENGTH(S) > 0 THEN

DBMS_OUTPUT.PUT_LINE('LAT:'||SUBSTR('32.8,63.5',1,INSTR('32.8,63.5',',',

1, 1)-1));

DBMS_OUTPUT.PUT_LINE('LON:'||SUBSTR('32.8,63.5',INSTR('32.8,63.5',',',

1, 1)+1));

-- COMMIT;

END IF;

T := SUBSTR(T, INSTR(T, ';') + 1);

END

LOOP;

END IF; end;