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  • PostgreSQL 9.2中将引入生成JSON数据功能

    以下是来自回归测试中的一些简单示例:

    SELECT query_to_json('select x as b, x * 2 as c from generate_series(1,3) x',false);
    query_to_json
    ---------------------------------------------
    [{"b":1,"c":2},{"b":2,"c":4},{"b":3,"c":6}]
    (1 row)

    SELECT array_to_json('{{1,5},{99,100}}'::int[]);
    array_to_json
    ------------------
    [[1,5],[99,100]]
    (1 row)

    -- row_to_json
    SELECT row_to_json(row(1,'foo'));
    row_to_json
    ---------------------
    {"f1":1,"f2":"foo"}
    (1 row)

    SELECT row_to_json(q)
    FROM (SELECT $$a$$ || x AS b,
    y AS c,
    ARRAY[ROW(x.*,ARRAY[1,2,3]),
    ROW(y.*,ARRAY[4,5,6])] AS z
    FROM generate_series(1,2) x,
    generate_series(4,5) y) q;
    row_to_json
    --------------------------------------------------------------------
    {"b":"a1","c":4,"z":[{"f1":1,"f2":[1,2,3]},{"f1":4,"f2":[4,5,6]}]}
    {"b":"a1","c":5,"z":[{"f1":1,"f2":[1,2,3]},{"f1":5,"f2":[4,5,6]}]}
    {"b":"a2","c":4,"z":[{"f1":2,"f2":[1,2,3]},{"f1":4,"f2":[4,5,6]}]}
    {"b":"a2","c":5,"z":[{"f1":2,"f2":[1,2,3]},{"f1":5,"f2":[4,5,6]}]}
    (4 rows)

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  • 原文地址:https://www.cnblogs.com/neights/p/2969323.html
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