create table t_row_str(
id int,
col varchar2(10));
insert into t_row_str values(1,'a');
insert into t_row_str values(1,'b');
insert into t_row_str values(1,'c');
insert into t_row_str values(2,'a');
insert into t_row_str values(2,'d');
insert into t_row_str values(2,'e');
insert into t_row_str values(3,'c');
commit;
select * from t_row_str;
5.1max + decode
適用範圍：
8i,9i,10g
及以後版本
select id,
max(decode(rn, 1, col, null)) ||
max(decode(rn, 2, ',' || col, null)) ||
max(decode(rn, 3, ',' || col, null)) str
from (select id,
col,
row_number() over(partition by id order by col) as rn
from t_row_str) t
group by id
order by 1;
5.2row_number + lead
適用範圍：
8i,9i,10g
及以後版本
select id, str
from (select id,
row_number() over(partition by id order by col) as rn,
col || lead(',' || col, 1) over(partition by id order by col) ||
lead(',' || col, 2) over(partition by id order by col) ||
lead(',' || col, 3) over(partition by id order by col) as str
from t_row_str)
where rn = 1
order by 1;
5.3model
適用範圍：
10g及以後版本
select id, substr(str, 2) str from t_row_str
model
return updated rows
partition by(id)
dimension by(row_number() over(partition by id order by col) as rn)
measures (cast(col as varchar2(20)) as str)
rules upsert
iterate(3) until( presentv(str[iteration_number+2],1,0)=0)
(str[0] = str[0] || ',' || str[iteration_number+1])
order by 1;
5.4sys_connect_by_path
適用範圍：
8i,9i,10g
及以後版本
select t.id id, max(substr(sys_connect_by_path(t.col, ','), 2)) str
from (select id, col, row_number() over(partition by id order by col) rn
from t_row_str) t
start with rn = 1
connect by rn = prior rn + 1
and id = prior id
group by t.id;
適用範圍：
10g及以後版本
select t.id id, substr(sys_connect_by_path(t.col, ','), 2) str
from (select id, col, row_number() over(partition by id order by col) rn
from t_row_str) t
where connect_by_isleaf = 1
start with rn = 1
connect by rn = prior rn + 1
and id = prior id;
5.5wmsys.wm_concat
適用範圍：
10g及以後版本
這個函式預定義按
','分隔字串，若要用其他符號分隔可以用，
replace
將','
替換。select id, replace(wmsys.wm_concat(col), ',', '/') str
from t_row_str
group by id;
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