从映射中选择特定值 [英] SELECT Specific Value from map

问题描述

我正在尝试创建一个WIDE列表，共有2万多列

最初我想我会使用：

  CREATE TABLE详细信息（
 key TEXT，
详细地图< TEXT，TEXT> 
 PRIMARY KEY（KEY）
）; 
 

插入此表格工作正常

  UPDATE details SET detail = detail + {'col1'：'12'}其中key ='123'; 
 UPDATE details SET detail = detail + {'col20000'：'ABCD'}其中key ='123';但是，我想阅读一个单独的细节：
 
 $ b 
 $ b 
  select detail [col1] where key ='123'
  
 
 $ b b 
当执行此查询时，我收到以下错误：
 在输入'['
 
 
 
 
这将有效吗，还是需要不同的方法？
 
 
 
如果您想以更细的级别访问元组，并且仍然能够询问给定键的所有数据对是什么，则应该使用这样的表：
  CREATE TABLE details（
 key TEXT，
 detail_key text，
 detail_value text，
 PRIMARY KEY（key，detail_key）
）; 
  
这将允许 SELECT * FROM details WHERE key =？以及 SELECT * FROM detail WHERE key =？ AND detail_key =？。
 
I am trying to create a WIDE Column Table, 20,000+ columns

Initially I was thinking I would use:
CREATE TABLE details (
   key TEXT,
   detail map<TEXT, TEXT>
   PRIMARY KEY (KEY)
  );
Inserting into this table works fine
UPDATE details SET detail = detail + { 'col1': '12'} where key='123' ;
UPDATE details SET detail = detail + { 'col20000': 'ABCD'} where key='123' ;
However, I would like to read an individual detail:
   select detail[col1] where key='123'
when executing this query I get the following error:
 no viable alternative at input '['
Will this work, or do I need a different approach?
解决方案
Collections are small groups of data that you fetch all at once.

If you want to access tuples at a finer level, and still be able to ask "what are all the pairs of data for a given key," you should use a table like this:
CREATE TABLE details (
  key TEXT,
  detail_key text,
  detail_value text,
  PRIMARY KEY (key, detail_key)
);
This will allow SELECT * FROM details WHERE key = ? as well as SELECT * FROM detail WHERE key = ? AND detail_key = ?.

                        
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