Oracle字符串拆分实例详解

admin Oracle

2023-12-04 0 290

Oracle字符串拆分

比如把一列 a,b,c 拆分为

abc

1. 使用regexp_substr()函数

1.1 拆分aaa,bbb,ccc

SELECT
regexp_substr(\’aaa,bbb,ccc\’, \'[^,]+\’, 1, LEVEL)
FROM
dual
CONNECT BY
LEVEL <= LENGTH(\’aaa,bbb,ccc\’)-LENGTH(REPLACE(\’aaa,bbb,ccc\’, \’,\’))+ 1;

输出结果：

1.2 拆分aaa;bbb;ccc

SELECT
regexp_substr(\’aaa;bbb;ccc\’, \'[^;]+\’, 1, LEVEL)
FROM
dual
CONNECT BY
LEVEL <= LENGTH(\’aaa;bbb;ccc\’)-LENGTH(REPLACE(\’aaa;bbb;ccc\’, \’;\’))+ 1;

1.3 level作用

SELECT LEVEL FROM dual CONNECT BY LEVEL<10;

2. 在oracle中实现MySQL的find_in_set()函数

2.1 使用oracle的函数定义函数FIND_IN_SET()

FIND_IN_SET(str,strlist)

CREATE OR REPLACE FUNCTION FIND_IN_SET(piv_str1 varchar2, piv_str2 varchar2, p_sep varchar2 := \’,\’)
RETURN NUMBER IS
l_idx number:=0;
str varchar2(500);
piv_str varchar2(500) := piv_str2;
res number:=0;
loopIndex number:=0;
BEGIN
IF instr(piv_str, p_sep, 1) = 0 THEN
IF piv_str = piv_str1 THEN
res:= 1;
END IF;
ELSE
LOOP
l_idx := instr(piv_str,p_sep);
loopIndex:=loopIndex+1;
IF l_idx > 0 THEN
str:= substr(piv_str,1,l_idx-1);
IF str = piv_str1 THEN
res:= loopIndex;
EXIT;
END IF;
piv_str := substr(piv_str,l_idx+length(p_sep));
ELSE
IF piv_str = piv_str1 THEN
res:= loopIndex;
END IF;
EXIT;
END IF;
END LOOP;
END IF;
RETURN res;
END FIND_IN_SET;

2.2 使用FIND_IN_SET()

查看aaa是否在aaa,bbb,ccc中

SELECT find_in_set(\’aaa\’,\’aaa,bbb,ccc\’) FROM dual;

返回1

查看bbb是否在aaa,bbb,ccc中

SELECT find_in_set(\’bbb\’,\’aaa,bbb,ccc\’) FROM dual;

返回2

查看ddd是否在aaa,bbb,ccc中

SELECT find_in_set(\’ddd\’,\’aaa,bbb,ccc\’) FROM dual;

返回0

2.3 删除函数FIND_IN_SET()

DROP FUNCTION FIND_IN_SET;

3. 使用存储过程输入aaa,bbb,ccc，拆分打印出来

3.1 定义存储过程

CREATE OR REPLACE PROCEDURE SPLIT_STR(STRLIST IN VARCHAR2)
IS
CURSOR CHECK_FLAG IS
SELECT REGEXP_SUBSTR(STRLIST, \'[^,]+\’, 1, LEVEL) F_VALUE
FROM DUAL
CONNECT BY LEVEL <=
LENGTH(STRLIST) – LENGTH(REPLACE(STRLIST, \’,\’)) + 1;
BEGIN
FOR REC IN CHECK_FLAG LOOP
DBMS_OUTPUT.PUT_LINE(REC.F_VALUE);
END LOOP;
END SPLIT_STR;