PostgreSQL 9.2中将引入生成JSON数据功能

fmms 10年前
     PostgreSQL开发者Andrew Dunstan    <a href="/misc/goto?guid=4958326103248420108" target="_blank">写到</a>:    <br />    <div class="quote_title">     引用    </div>    <div class="quote_div">     上周三,也就是PostgreSQL 9.2最后一个     <a href="/misc/goto?guid=4958326104059031135" target="_blank">commitfest</a>到来的前四天,Robert Haas提交了一个名为     <a href="/misc/goto?guid=4958326104854642107" target="_blank">JSON for 9.2</a>的补丁,欲将JSON列为PostgreSQL的核心类型。基本上,该补丁功能是对文本进行解析,确保它是有效的JSON数据,并加以存储。这个功能我原本打算在9.2版本中放弃的,不过我考虑了下发现Robert的补丁太小了点,因此决定继续并又添加了一些功能,包括:query_to_json()、 array_to_json()以及record_to_json(),完成了从ProstgreSQL生成JSON数据。    </div>    <br /> 以下是来自回归测试中的一些简单示例:    <pre class="brush:sql; toolbar: true; auto-links: false;">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)</pre>更简单一点的:    <pre class="brush:sql; toolbar: true; auto-links: false;">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)</pre>Via     <a href="/misc/goto?guid=4958326103248420108" target="_blank">planetpostgresql</a>    <br /> 来自:    <a href="/misc/goto?guid=4958326106375777161" target="_blank">http://www.iteye.com/news/24032</a>