问题描述

我有一个这种形式的表格(这只是部分视图，表格包含 100 多列).

I have a table in this form (this is just the partial view, the table contains more than 100 columns).

 LOAN NUMBER   DOCUMENT_TYPE                DOCUMENT_ID
 992452533663  Voters ID                    XPD0355636
 992452533663  Pan card                     CHXPS5522D
 992452533663  Drivers licence              DL-0420110141769

一个贷款号，我有三种文件作为证明.我希望将这些详细信息转换为列并采用以下形状:

For a single loan number, I have three kinds of documents as proof. I want these details to be converted into columns and take the following shape:

LOAN NUMBER     VOTERS_ID    PAN_CARD     DRIVERS LICENCE
992452533663    XPD0355636   CHXPS5522D   DL-0420110141769

如何解决这个问题?

推荐答案

如果您使用的是 Oracle 10g，则可以使用 DECODE 函数将行转为列:

If you are using Oracle 10g, you can use the DECODE function to pivot the rows into columns:

CREATE TABLE doc_tab (
  loan_number VARCHAR2(20),
  document_type VARCHAR2(20),
  document_id VARCHAR2(20)
);

INSERT INTO doc_tab VALUES('992452533663', 'Voters ID', 'XPD0355636');
INSERT INTO doc_tab VALUES('992452533663', 'Pan card', 'CHXPS5522D');
INSERT INTO doc_tab VALUES('992452533663', 'Drivers licence', 'DL-0420110141769');

COMMIT;

SELECT
    loan_number,
    MAX(DECODE(document_type, 'Voters ID', document_id)) AS voters_id,
    MAX(DECODE(document_type, 'Pan card', document_id)) AS pan_card,
    MAX(DECODE(document_type, 'Drivers licence', document_id)) AS drivers_licence
  FROM
    doc_tab
GROUP BY loan_number
ORDER BY loan_number;

输出:

LOAN_NUMBER   VOTERS_ID            PAN_CARD             DRIVERS_LICENCE    
------------- -------------------- -------------------- --------------------
992452533663  XPD0355636           CHXPS5522D           DL-0420110141769     

您可以使用 11g 中引入的 Oracle PIVOT 子句实现相同的目的:

You can achieve the same using Oracle PIVOT clause, introduced in 11g:

SELECT *
  FROM doc_tab
PIVOT (
  MAX(document_id) FOR document_type IN ('Voters ID','Pan card','Drivers licence')
);

带有两种解决方案的 SQLFiddle 示例:SQLFiddle 示例

SQLFiddle example with both solutions: SQLFiddle example

在此处阅读有关透视的更多信息:透视蒂姆·霍尔的甲骨文

Read more about pivoting here: Pivot In Oracle by Tim Hall

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