[英]Oracle: Translate subselect into pipelined function?
我一般如何將子選擇轉換為流水線函數調用?
例如,我將如何翻譯:
select id, stuff from t1 where id in (select unique id from kw where k = 'foo')
對此:
select id, stuff from t1 where id in (select id from table(has_kw('foo'))
編寫流水線表函數相對簡單
CREATE TYPE num_tbl AS TABLE OF NUMBER;
CREATE FUNCTION has_kw( p_k IN VARCHAR2 )
RETURN num_tbl
PIPELINED
IS
BEGIN
FOR i IN (SELECT DISTINCT id FROM kw WHERE k = p_k)
LOOP
PIPE ROW( i.id );
END LOOP;
RETURN;
END;
現在,我不確定在這里使用pipeliend表函數是否真的有意義。 但是,也許您的實際用例更加復雜,而流水線表函數會更合適。
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