Oracle中instr、substr函数的使用和split功能的实现

本文转自： http://blog.csdn.net/yhb315279058 https://blog.csdn.net/yhb315279058/article/details/41977585

substr(str,index1,n)
取字符串str，位置index1后面的n个字符，index1取1或0都代表第一个字符。

instr(str,sub,dire,times)
获取字符串str，的子串sub的位置。dire取1代表从左到右找，dire取-1代表从右到左找。times代表找第几个。如果times超出范围，函数返回0。

用法对比如下：
substr


    
    
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'substr(''abcdefghi'',1,4)' FUN,
        
        substr(
        
        'abcdefghi',
        
        1,
        
        4) 
        
        RESULT 
        
        FROM dual 
        
        union all
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'substr(''abcdefghi'',0,4)' FUN,
        
        substr(
        
        'abcdefghi',
        
        0,
        
        4) 
        
        RESULT 
        
        FROM dual 
        
        union all
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'substr(''abcdefghi'',2,4)' FUN,
        
        substr(
        
        'abcdefghi',
        
        2,
        
        4) 
        
        RESULT 
        
        FROM dual ;

instr


    
    
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'INSTR(''ABCABCABCABC'',''A'',1,1)' FUN, 
        
        INSTR(
        
        'ABCABCABCABC',
        
        'A',
        
        1,
        
        1) 
        
        RESULT 
        
        FROM DUAL 
        
        UNION ALL
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'INSTR(''ABCABCABCABC'',''A'',1,1)' FUN, 
        
        INSTR(
        
        'ABCABCABCABC',
        
        'A',
        
        1,
        
        2) 
        
        RESULT 
        
        FROM DUAL 
        
        UNION ALL
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'INSTR(''ABCABCABCABC'',''A'',1,1)' FUN, 
        
        INSTR(
        
        'ABCABCABCABC',
        
        'A',
        
        -1,
        
        1) 
        
        RESULT 
        
        FROM DUAL 
        
        UNION ALL
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'INSTR(''ABCABCABCABC'',''A'',1,1)' FUN, 
        
        INSTR(
        
        'ABCABCABCABC',
        
        'A',
        
        -1,
        
        2) 
        
        RESULT 
        
        FROM DUAL;

PL/SQL没有split函数，要使用split函数的时候需要自己写一个。我自己写了一个oracle函数，如下：


    
    
     
     
      
      
       
       
      
      
      
      
       
       
        
        create 
        
        or 
        
        replace 
        
        function SPLITER(p_value varchar2 ,
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
                                            p_split varchar2 := 
        
        ',' ,times 
        
        integer := 
        
        1)
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        --参数1 表示字符串，参数2 为分隔符，参数3 为第几个
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
        
        
        return  varchar2 
        
        as
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
          v_idx1       
        
        integer;
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
          v_idx2       integer;
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
          v_strs_last varchar2(4000 ) := p_value;
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        begin
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
         
        
        if times= 
        
        1 
        
        then
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
           
        
        return 
        
        substr(v_strs_last,
        
        1 ,
        
        instr(v_strs_last,p_split,
        
        1, 
        
        1)
        
        -1 );
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
         
        
        end 
        
        if;
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
            v_idx1 := instr(v_strs_last, p_split, 1,times-1 );
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
            v_idx2 := instr(v_strs_last, p_split, 1,times);
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
          if v_idx2= 0 then
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
            return substr(v_strs_last,v_idx1+1 );
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
         
        
        end 
        
        if;
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
          return substr(v_strs_last,v_idx1+ 1,v_idx2-v_idx1-1 );
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        end SPLITER;

效果如下：


    
    
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'spliter(''111,222,333,444,555'','','',1)' fun,spliter(
        
        '111,222,333,444,555',
        
        ',',
        
        1) 
        
        result 
        
        FROM dual 
        
        union all
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'spliter(''111,222,333,444,555'','','',2)' fun,spliter(
        
        '111,222,333,444,555',
        
        ',',
        
        2) 
        
        result 
        
        FROM dual 
        
        union all
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'spliter(''111,222,333,444,555'','','',3)' fun,spliter(
        
        '111,222,333,444,555',
        
        ',',
        
        3) 
        
        result 
        
        FROM dual 
        
        union all
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'spliter(''111,222,333,444,555'','','',4)' fun,spliter(
        
        '111,222,333,444,555',
        
        ',',
        
        4) 
        
        result 
        
        FROM dual 
        
        union all
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'spliter(''111,222,333,444,555'','','',5)' fun,spliter(
        
        '111,222,333,444,555',
        
        ',',
        
        5) 
        
        result 
        
        FROM dual 
        
        union all
       
       
      
      
     
     
      
      
       
       
      
      
      
      
       
       
        
        SELECT 
        
        'spliter(''111,222,333,444,555'','','',6)' fun,spliter(
        
        '111,222,333,444,555',
        
        ',',
        
        6) 
        
        result 
        
        FROM dual;