oracle操作字符串:拼接、替换、截取、查找、长度、判断

1、拼接字符串

1)可以使用“||”来拼接字符串

select '拼接'||'字符串' as str from dual 

2)通过concat()函数实现

select concat('拼接', '字符串') as str from dual 

注:oracle的concat函数只支持两个参数的方法,即只能拼接两个参数,如要拼接多个参数则嵌套使用concat可实现,如:

select concat(concat('拼接', '多个'), '字符串') from dual 

2、截取字符串

SUBSTR(string,start_position,[length])    求子字符串,返回字符串
解释:string 源字符串
       start_position   开始位置(从0开始)
       length 可选项,子字符串的个数

select substr(to_char(sysdate, 'yyyy-mm-dd HH:mi:ss'), 12, 5) as time from dual
substr("ABCDEFG", 0); //返回:ABCDEFG,截取所有字符 
substr("ABCDEFG", 2); //返回:CDEFG,截取从C开始之后所有字符 
substr("ABCDEFG", 0, 3); //返回:ABC,截取从A开始3个字符 
substr("ABCDEFG", 0, 100); //返回:ABCDEFG,100虽然超出预处理的字符串最长度,但不会影响返回结果,系统按预处理字符串最大数量返回。 
substr("ABCDEFG", -3); //返回:EFG,注意参数-3,为负值时表示从尾部开始算起,字符串排列位置不变。

字符串 "AAA-BBB" 截取"AAA"  "BBB"

select substr('AAA-BBB',1,instr('AAA-BBB','-',-1)-1) 值 from dual;
select substr('AAA-BBB',instr('AAA-BBB','-',-1)+1) 值 from dual;

3、查找字符串

INSTR(string,subString,position,ocurrence)查找字符串位置

解释:string:源字符串
        subString:要查找的子字符串
        position:查找的开始位置
        ocurrence:源字符串中第几次出现的子字符串

select INSTR('CORPORATE FLOOR','OR', 3, 2) as loc from dual 

4、替换字符串

replace(strSource, str1, str2) 将strSource中的str1替换成str2

解析:strSource:源字符串

     str1: 要替换的字符串

     str2: 替换后的字符串

select '替换字符串' as oldStr, replace('替换字符串', '替换', '修改') as newStr from dual

5、长度

 length(nvl(字段,''))=1

6、判断

SELECT SBXH, SFZJHM, 
        case
       when length(nvl(XM,''))=1 then XM
         when length(nvl(XM,''))=2 then substr(XM, 0, 1)||'*'
       when length(nvl(XM,''))=3 then substr(XM, 0, 1)||'**'
       when length(nvl(XM,''))=4 then substr(XM, 0, 1)||'***'
       else substr(XM, 0, 1)||'****'
     end XM,
       DJXH, SDNF, DWMC, YNSE
    FROM ZHZS_SEWSR T
    WHERE YNSE > 120000.000000 AND DWMC IS NOT NULL AND SFZJHM LIKE '36%'
    ORDER BY YNSE DESC

 

posted @ 2018-01-10 16:44  残星  阅读(12834)  评论(1编辑  收藏