對XML

Question

如何concate連接表的字段

嗨具有數據結構是這樣的：

<info> 
    <maininfo> 
    <pn name="name">name1</pn> 
    <age name="age">10</age> 
    </maininfo> 
    <data> 
    <row> 
     <col1 name="col1">2</col1> 
     <col2 name="col2">3</col1> 
     <col3 name="col3">4</col1> 
    </row> 
    <row> 
     <col1 name="col1">5</col1> 
     <col2 name="col2">6</col1> 
     <col3 name="col3">7</col1> 
    </row> 
    <row> 
     <col1 name="col1">8</col1> 
     <col2 name="col2">9</col1> 
     <col3 name="col3">10</col1> 
    </row> 
    </data> 

    <maininfo> 
    <pn name="name">name2</pn> 
    <age name="age">20</age> 
    </maininfo> 
    <data> 
    <row> 
     <col1 name="col1">20</col1> 
     <col2 name="col2">21</col1> 
     <col3 name="col3">22</col1> 
    </row> 
    <row> 
     <col1 name="col1">23</col1> 
     <col2 name="col2">24</col1> 
     <col3 name="col3">25</col1> 
    </row> 
    </data> 

</info> 

如何做到這一點：

CREATE TEMP TABLE test_names (
    id serial primary key, 
    name character varying(50), 
    age int 
); 

INSERT INTO test_names(name,age) values ('name1',10),('name2',20); 

CREATE TEMP TABLE test_names_details (
    id serial primary key, 
    test_names_id int, 
    col1 int, 
    col2 int, 
    col3 int 
); 

INSERT INTO test_names_details(test_names_id,col1,col2,col3) 
VALUES(1,2,3,4),(1,5,6,7),(1,8,9,10),(2,20,21,22),(2,23,24,25) 

從該表中選擇數據，如XML想要什麼？

Answer 1

將此功能包裝在一個功能中，然後關閉！ ;-)

SELECT 
'<info>' || 
    string_agg(
    '<maininfo>' || 
     '<pn name="name">' || name || '</pn>' || 
     '<age name="age">' || age || '</age>' || 
    '</maininfo>' || 
    '<data>' || 
     (SELECT 
      string_agg(
     '<row>' || 
      '<col name="col1">'||col1||'</col>' || 
      '<col name="col2">'||col2||'</col>' || 
      '<col name="col3">'||col3||'</col>' || 
     '</row>', '') 
     FROM test_names_details WHERE test_names_id = test_names.id 
     ) || 
    '</data>' 
    , '') || 
'</info>' 
FROM test_names