Tôi đã tạo giải pháp này trước khi tôi gặp ListAgg, nhưng vẫn có những dịp, chẳng hạn như vấn đề giá trị trùng lặp này, thì công cụ này rất hữu ích. Phiên bản dưới đây có 4 đối số để cung cấp cho bạn quyền kiểm soát kết quả.
Giải thích CLOBlist lấy CLOBlistParam của bộ điều phối làm tham số. CLOBlistParam có 4 đối số
string VARCHAR2(4000) - The variable to be aggregated
delimiter VARCHAR2(100) - The delimiting string
initiator VARCHAR2(100) - An initial string added before the first value only.
no_dup VARCHAR2(1) - A flag. Duplicates are suppressed if this is Y
Ví dụ sử dụng
--vertical list of comma separated values, no duplicates.
SELECT CLOBlist(CLOBlistParam(column_name,chr(10)||',','','Y')) FROM user_tab_columns
--simple csv
SELECT CLOBlist(CLOBlistParam(table_name,',','','N')) FROM user_tables
Liên kết đến Gist ở bên dưới.
https://gist.github.com/peter-genesys/d203bfb3d88d5a5664a86ea6ee34eeca] 1
-- Program : CLOBlist
-- Name : CLOB list
-- Author : Peter Burgess
-- Purpose : CLOB list aggregation function for SQL
-- RETURNS CLOB - to allow for more than 4000 chars to be returned by SQL
-- NEW type CLOBlistParam - allows for definition of the delimiter, and initiator of sequence
------------------------------------------------------------------
--This is an aggregating function for use in SQL.
--It takes the argument and creates a comma delimited list of each instance.
WHENEVER SQLERROR CONTINUE
DROP TYPE CLOBlistImpl;
WHENEVER SQLERROR EXIT FAILURE ROLLBACK
create or replace type CLOBlistParam as object(
string VARCHAR2(4000)
,delimiter VARCHAR2(100)
,initiator VARCHAR2(100)
,no_dup VARCHAR2(1) )
/
show error
--Creating CLOBlist()
--Implement the type CLOBlistImpl to contain the ODCIAggregate routines.
create or replace type CLOBlistImpl as object
(
g_list CLOB, -- progressive concatenation
static function ODCIAggregateInitialize(sctx IN OUT CLOBlistImpl)
return number,
member function ODCIAggregateIterate(self IN OUT CLOBlistImpl
, value IN CLOBlistParam) return number,
member function ODCIAggregateTerminate(self IN CLOBlistImpl
, returnValue OUT CLOB
, flags IN number) return number,
member function ODCIAggregateMerge(self IN OUT CLOBlistImpl
, ctx2 IN CLOBlistImpl) return number
)
/
show error
--Implement the type body for CLOBlistImpl.
create or replace type body CLOBlistImpl is
static function ODCIAggregateInitialize(sctx IN OUT CLOBlistImpl)
return number is
begin
sctx := CLOBlistImpl(TO_CHAR(NULL));
return ODCIConst.Success;
end;
member function ODCIAggregateIterate(self IN OUT CLOBlistImpl
, value IN CLOBlistParam) return number is
begin
IF self.g_list IS NULL THEN
self.g_list := value.initiator||value.string;
ELSIF value.no_dup = 'Y' AND
value.delimiter||self.g_list||value.delimiter LIKE '%'||value.delimiter||value.string||value.delimiter||'%'
THEN
--Do not include duplicate value
NULL;
ELSE
self.g_list := self.g_list||value.delimiter||value.string;
END IF;
return ODCIConst.Success;
end;
member function ODCIAggregateTerminate(self IN CLOBlistImpl
, returnValue OUT CLOB
, flags IN number) return number is
begin
returnValue := self.g_list;
return ODCIConst.Success;
end;
member function ODCIAggregateMerge(self IN OUT CLOBlistImpl
, ctx2 IN CLOBlistImpl) return number is
begin
self.g_list := LTRIM( self.g_list||','||ctx2.g_list,',');
return ODCIConst.Success;
end;
end;
/
show error
--Using CLOBlist() to create a vertical list of comma separated values
-- SELECT CLOBlist(CLOBlistParam(product_code,chr(10)||',','','Y'))
-- FROM account
--DROP FUNCTION CLOBlist
--/
PROMPT Create the user-defined aggregate.
CREATE OR REPLACE FUNCTION CLOBlist (input CLOBlistParam) RETURN CLOB
PARALLEL_ENABLE AGGREGATE USING CLOBlistImpl;
/
show error
order by nullcóorder by Num2hay tôi đang bối rối?