Oracle 兑现拆分列数据的split()方法

Oracle 实现拆分列数据的split()方法

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-- 创建需要划分的字符串
with T1 as(
   select 'one,two,three,four,five,six,seven,eight,nine,zero' as source_string
     from dual),
   
-- 统计字符串中子串的个数，用 ',' 来划分子串
T2 as(
   select regexp_count(source_string, '[^,]+') as source_substring_count
     from T1),
   
-- 根据子串的个数创建索引列，用于给T4的regexp_substr()方法索引
T3 as(
   select rownum as row_number
     from dual, T2
   connect by rownum <= T2.source_substring_count),
   
-- 根据每个索引值逐个截取字符串
T4 as(
   select T3.row_number as substring_index,
          regexp_substr(T1.source_string, '[^,]+', 1, T3.row_number) as substring
     from T1, T3)
   
select substring_index, substring from T4;

 

鉴于 regexp_count() 方法是 Oracle 11g 才新加上的，之前的版本并没有，这里再用另一种方法来统计子串的个数：

-- 创建需要划分的字符串
with T1 as(
   select 'one,two,three,four,five,six,seven,eight,nine,zero' as source_string
     from dual),
   
-- 统计字符串中子串的个数
-- 字符串中','字符用''代替后，其减少的长度自然就是原串中','字符的个数
T2 as(
   select length(T1.source_string) - length(replace(T1.source_string, ',', '')) + 1
          as source_substring_count
     from T1),
   
-- 根据子串的个数创建索引列，用于给T4的regexp_substr()方法索引
T3 as(
   select rownum as row_number
     from dual, T2
   connect by rownum <= T2.source_substring_count),
   
-- 根据每个索引值逐个截取字符串
T4 as(
   select T3.row_number as substring_index,
          regexp_substr(T1.source_string, '[^,]+', 1, T3.row_number) as substring
     from T1, T3)
   
select substring_index, substring from T4;

 

运行结果：