的Oracle 11g拆分文本列行

Question

我有表：

ID |Values 
-----+-------------------------------- 
1 |AB,AD 
2 |AG, ... ,BD 
3 |AV 

我怎樣才能把它轉換爲：

ID |Value 
-----+------ 
1 |AB 
1 |AD 
2 |AG 
... |... 
2 |BD 
3 |AV 

Answer 1

使用內置的XML功能，你可以做這樣的：

with sample_data as 
(
select 1 id, 'AB,AD' vals from dual union all 
select 2, 'AG,AK,AJ,BA,BD' from dual union all 
select 3, 'AV' from dual 
) 
select id, cast(t.column_value.extract('//text()') as varchar2(10)) val 
    from sample_data, 
    table(xmlsequence(xmltype(
    '<x><x>' || replace(vals, ',', '</x><x>') || '</x></x>' 
).extract('//x/*'))) t; 

結果：

ID VAL 
--- ----- 
1 AB 
1 AD 
2 AG 
2 AK 
2 AJ 
2 BA 
2 BD 
3 AV 

Answer 2

使用遞歸公用表表達式，相同的查詢看起來是這樣的：

with sample_data as 
(
    select 1 id, 'AB,AD' vals from dual union all 
    select 2, 'AG,AK,AJ,BA,BD' from dual union all 
    select 3, 'AV' from dual 
), 
split_first(id, val, rem) as 
(
    select id, 
    coalesce(substr(vals, 1, instr(vals, ',') - 1), vals) val, 
    case when instr(vals, ',') > 0 then substr(vals, instr(vals, ',') + 1) end rem 
    from sample_data 
    union all 
    select id, 
    coalesce(substr(rem, 1, instr(rem, ',') - 1), rem) val, 
    case when instr(rem, ',') > 0 then substr(rem, instr(rem, ',') + 1) end rem 
    from split_first 
    where rem is not null 
) 
select id, val from split_first 
order by id; 

或者稍微不同的方法：

with sample_data as 
(
    select 1 id, 'AB,AD' vals from dual union all 
    select 2, 'AG,AK,AJ,BA,BD' from dual union all 
    select 3, 'AV' from dual 
), 
pos(id, seq, vals, sta, stp) as 
(
    select id, 1, vals, 1, instr(vals, ',') from sample_data 
    union all 
    select id, seq + 1, vals, stp + 1, instr(vals, ',', stp + 1) from pos 
    where stp > 0 
) 
select id, substr(vals, sta, case when stp > 0 then stp - sta else length(vals) end) from pos 
order by id, seq;