[英]alternative to listagg in Oracle?
listagg是Oracle 11.2中引入的一个函数! 现在这个功能正在困扰我们分配,我们正在从MySQL迁移到Oracle,我们有这个查询:
SELECT
p_id,
MAX(registered) AS registered,
listagg(MESSAGE, ' ') within GROUP (ORDER BY registered) AS MESSAGE
FROM
umm_parent_id_remarks_v m
GROUP BY
m.p_id;
只要我们知道在Oracle下面有什么烦恼它就会返回VARCAR而不是我们需要的CLOB! 文字很大,我们确实需要它是CLOB !
这是我试图做的!
创建一个CLOB类型的CLOB_T表!
然后创建功能
create or replace
function listaggclob (t in clob_t)
return clob
as
ret clob := '';
i number;
begin
i := t.first;
while i is not null loop
if ret is not null then
ret := ret || ' ';
end if;
ret := ret || t(i);
i := t.next(i);
end loop;
return ret;
end;
现在,如果我运行它:
SELECT
p_id,
MAX(registered) AS registered,
listaggclob(cast(collect (MESSAGE) as clob_t)) MESSAGE
FROM
umm_parent_id_remarks_v m
GROUP BY
m.p_id;
我明白了
ORA-22814:属性或元素值大于类型中指定的值
它有什么解决方案吗?
谢谢
WM_CONCAT为我工作。
SELECT replace(WMSYS.WM_CONCAT(myTable.name), ',', ';')
FROM myTable
GROUP BY myTable.id
我用“替换”包装它以指定与WM_CONCAT(',')使用的分隔符不同的项目分隔符(';')。
使用xmlAgg,示例如下所示:
SELECT RTRIM(XMLAGG(XMLELEMENT(E,colname,',').EXTRACT('//text()') ORDER BY colname).GetClobVal(),',') AS LIST
FROM tablename;
这将返回clob值,因此无需创建自定义函数。
您可以使用MULTISET
而不是COLLECT
来解决ORA-22814
错误:
SELECT
p_id,
MAX(registered) AS registered,
listaggclob(cast(multiset(
select MESSAGE
from umm_parent_id_remarks_v
where umm_parent_id_remarks_v.p_id = m.p_id
) as clob_t)) MESSAGE
FROM
umm_parent_id_remarks_v m
GROUP BY
m.p_id;
- 创建Clobe类型 - 创建或替换类型“MSCONCATIMPL_CLOB”作为对象(结果字符串CLOB,分隔符VARCHAR2(10),
STATIC FUNCTION odciaggregateinitialize ( io_srccontext IN OUT msconcatimpl_clob ) RETURN NUMBER,
MEMBER FUNCTION odciaggregateiterate (
self IN OUT msconcatimpl_clob,
value IN CLOB
) RETURN NUMBER,
MEMBER FUNCTION odciaggregateterminate (
self IN msconcatimpl_clob,
o_returnvalue OUT CLOB,
i_flags IN NUMBER
) RETURN NUMBER,
MEMBER FUNCTION odciaggregatemerge (
self IN OUT msconcatimpl_clob,
i_ctx2 IN msconcatimpl_clob
) RETURN NUMBER
); / - 创建Clobe Type Body -
创建或替换类型身体“MSCONCATIMPL_CLOB”是静态功能odciaggregateinitialize(io_srccontext IN OUT msconcatimpl_clob)返回号码是否开始io_srccontext:= msconcatimpl_clob(NULL,NULL); io_srccontext.delimiter:=''; 返回odciconst.success; END odciaggregateinitialize;
MEMBER FUNCTION odciaggregateiterate (
self IN OUT msconcatimpl_clob,
value IN CLOB
) RETURN NUMBER
IS
BEGIN
IF
value IS NOT NULL
THEN
IF
self.resultstring IS NULL
THEN
self.resultstring := self.resultstring || value;
ELSE
self.resultstring := self.resultstring
|| self.delimiter
|| value;
END IF;
END IF;
RETURN odciconst.success;
END odciaggregateiterate;
MEMBER FUNCTION odciaggregateterminate (
self IN msconcatimpl_clob,
o_returnvalue OUT CLOB,
i_flags IN NUMBER
) RETURN NUMBER
IS
BEGIN
o_returnvalue := self.resultstring;
RETURN odciconst.success;
END odciaggregateterminate;
MEMBER FUNCTION odciaggregatemerge (
self IN OUT msconcatimpl_clob,
i_ctx2 IN msconcatimpl_clob
) RETURN NUMBER
IS
BEGIN
IF
self.resultstring IS NULL
AND
i_ctx2.resultstring IS NOT NULL
THEN
self.resultstring := i_ctx2.resultstring;
ELSIF
self.resultstring IS NOT NULL
AND
i_ctx2.resultstring IS NOT NULL
THEN
self.resultstring := self.resultstring
|| self.delimiter
|| i_ctx2.resultstring;
END IF;
RETURN odciconst.success;
END odciaggregatemerge;
结束; /
- 创建Clobe功能 -
创建或替换函数ms_concat_clob(输入VARCHAR2)使用msconcatimpl_clob返回CLOB PARALLEL_ENABLE AGGREGATE; /
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