他的建议是使用jsonb_agg(element ORDER BY expression)。我不得不在函数之外使用ORDER BY子句，我必须...
sql SELECT order_number, product_name, sales_quantity FROM sales_orders GROUP BY order_number; 步骤2:使用json_agg函数 使用json_agg函数将每个组的产品名称和销售数量转换为一个 JSON 数组,并将其命名为products字段。json_agg函数将指定的字段作为输入,并将其值合并为 JSON 数组。最后,我们将其作为一个名...
另一种常用的技术是 array_agg 和 array_to_json。array_agg 是一个聚合函数 sum 或 count。它聚集成一个 PostgreSQL 数组参数。array_to_json 以 PostgreSQL数组 拼合成一个单一的JSON值。 我们来看看 array_to_json 的用法: 1 2 3 4 selectarray_to_json(array_agg(row_to_json(t))) from( selectid...
The JSON_AGG() function aggregates only those employees’ names whose id is less than or equal to 5. Example 4: Using the JSON_AGG() Function With GROUP BY Clause Use the GROUP BY clause with the JSON_AGG() function to group the aggregated data: SELECT joining_date, JSON_AGG(emp_nam...
–geometry转geojson SELECT ST_AsGeoJSON ( geom ) FROM warning_products LIMIT 1 –xy坐标转geometry update “byc” set geom = ST_SetSRID(ST_Point(replace(x,‘E’,‘’)::float8,replace(y,‘N’,‘’)::float8),4326) –wkt转geometry ...
SELECT json_agg(my_column) FROM my_table; This will produce a JSON array that encompasses the values found in the “my_column” column of the “my_table” table. 5. jsonb_set function This function modifies a JSON object field by assigning it a new value. For example, ...
(selectarray_to_json(array_agg(row_to_json(d)))from(selectpart_of_speech, bodyfromdefinitionswhereword_id=words.idorderbyposition asc ) d )asdefinitionsfromwordswheretext='autumn') t This could return a result like the following: {
将每一行的数据存储为的缺点之一jsonb是基于列值的过滤变得非常低效。如果想快速查找一行的历史记录，需要为每一行提取和索引一个唯一标识符。对于全局唯一标识符，使用以下结构：[table_oid, primary_key_value_1, primary_key_value_2, ...]并将该数组散列为UUID v5以获得有效的可索引UUID类型，以识别对数据...
https://www.postgresql.org/message-id/12237.1582833074%sss.pgh.pa.us Less-silly selectivity for JSONB matching operators https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=a80818605e5447b9b846590c3d3fab99060cb53e pg_stat_slru 查看slru的统计信息...
select row_to_json(t)from (select text, pronunciation,(select array_to_json(array_agg(row_to_json(d)))from (select part_of_speech, body from definitions where word_id=words.id order by position asc ) d ) as definitions from words where text = 'autumn'上⾯查询语句返回结果如下：{ "...