用Oracle转置选择结果 [英] Transpose select results with Oracle
问题描述
我的问题是,有一些背景:
my question is, with some background:
我必须基于表元数据(列格式)生成一些sql查询,其结果类似于:
I have to generate some sql queries based on the table metadata (column format), and the result is something like:
TABLENAME1|COL1
TABLENAME1|COL2
TABLENAME2|COL1
TABLENAME2|COL2
TABLENAME2|COL3
TABLENAME3|COL1
TABLENAME4|COL1
TABLENAME4|COL2
... /*some other 1800 rows */
(是的,已订购.) 我需要的是根据第一列对这些数据进行转置,因此预期的输出将是:
(Yeah, it's ordered.) What I need is to transpose this data, based on the first column, so the expected output would be:
TABLENAME1|COL1|COL2|NULL
TABLENAME2|COL1|COL2|COL3
TABLENAME3|COL1|NULL|NULL
TABLENAME4|COL1|COL2|NULL
/* less then 1800 rows ;-) */
是否可以使用Oracle SQL?
Is it possible using Oracle SQL?
提前谢谢!
推荐答案
如果要为每个调用生成查询或使用硬编码的max-column-count,则可以执行以下操作:
If you want to generate the query for each call or use a hardcoded max-column-count, then you can do something like that:
WITH tab AS
(
SELECT table_name, column_name FROM user_tab_cols WHERE column_id <= 4
) -- user_tab_cols used to provide test data, use your table instead
SELECT MAX(c1) c1,
MAX(c2) c2,
MAX(c3) c3,
MAX(c4) c4
FROM (SELECT table_name,
DECODE( column_id, 1, column_name ) c1,
DECODE( column_id, 2, column_name ) c2,
DECODE( column_id, 3, column_name ) c3,
DECODE( column_id, 4, column_name ) c4
FROM ( SELECT table_name,
column_name,
ROW_NUMBER() OVER ( PARTITION BY table_name ORDER BY column_name ) column_id
FROM tab
)
)
GROUP BY table_name
ORDER BY table_name
如果能够以这种形式获得足够的信息
If it is sufficient to get it in that form
TABLENAME1|COL1,COL2
TABLENAME2|COL1,COL2,COL3
看看汤姆·凯特(Tom Kyte)的 stragg .
have a look at Tom Kyte's stragg.
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