当我从Oracle中选择表时,我想处理一个col'val: 例如:
'ab,cd,ef' to 'ef->cd->ab';
'AB,BC' to 'BC->AB';
'ACNN,BBCCAC' to 'BBCCAC->ACNN';
'BBBDC,DCCX,FFF' to 'FFF->DCCX->BBBDC'
答案 0 :(得分:3)
我们有两项任务。第一种是对原始字符串进行标记。正则表达式很容易(尽管there are more performant approaches if you are dealing with large volumes)。第二个任务是以相反的顺序重新组装令牌;我们可以使用11gR2 LISTAGG()函数:
with tokens as (
select distinct col1, regexp_substr(col1, '[^,]+', 1, level) as tkn, level as rn
from t23
connect by level <= regexp_count (col1, '[,]') +1
)
select col1
, listagg(tkn, '->')
within group (order by rn desc) as rev_col1
from tokens
group by col1
/
这是a SQL Fiddle。
答案 1 :(得分:0)
您可以将字符串拆分和字符串聚合混合使用。
使用:
您可以查看一下本文,了解字符串拆分的工作原理http://lalitkumarb.wordpress.com/2015/03/04/split-comma-delimited-strings-in-a-table-using-oracle-sql/
SQL> WITH DATA AS(
2 SELECT 1 ID, 'ab,cd,ef' text FROM dual UNION ALL
3 SELECT 2 ID, 'AB,BC' text FROM dual UNION ALL
4 SELECT 3 ID, 'ACNN,BBCCAC' text FROM dual
5 )
6 SELECT ID,
7 listagg(text, ',') WITHIN GROUP (
8 ORDER BY rn DESC) reversed_indices
9 FROM
10 (SELECT t.id,
11 rownum rn,
12 trim(regexp_substr(t.text, '[^,]+', 1, lines.COLUMN_VALUE)) text
13 FROM data t,
14 TABLE (CAST (MULTISET
15 (SELECT LEVEL FROM dual CONNECT BY LEVEL <= regexp_count(t.text, ',')+1
16 ) AS sys.odciNumberList ) ) lines
17 ORDER BY ID
18 )
19 GROUP BY ID
20 /
ID REVERSED_INDICES
---------- ------------------------------
1 ef,cd,ab
2 BC,AB
3 BBCCAC,ACNN
SQL>
假设您的表格如下:
SQL> SELECT * FROM t;
ID TEXT
---------- ------------------------------
1 ab,cd,ef
2 AB,BC
3 ACNN,BBCCAC
4 word1,word2,word3
5 1,2,3
SQL>
使用上述查询:
SQL> SELECT ID,
2 listagg(text, '-->') WITHIN GROUP (
3 ORDER BY rn DESC) reversed_indices
4 FROM
5 (SELECT t.id,
6 rownum rn,
7 trim(regexp_substr(t.text, '[^,]+', 1, lines.COLUMN_VALUE)) text
8 FROM t,
9 TABLE (CAST (MULTISET
10 (SELECT LEVEL FROM dual CONNECT BY LEVEL <= regexp_count(t.text, ',')+1
11 ) AS sys.odciNumberList ) ) lines
12 ORDER BY ID
13 )
14 GROUP BY ID
15 /
ID REVERSED_INDICES
---------- ------------------------------
1 ef-->cd-->ab
2 BC-->AB
3 BBCCAC-->ACNN
4 word3-->word2-->word1
5 3-->2-->1
SQL>