基本UPDATE

使用以下更短，更高效的单个UPDATE命令替换第一个查询:

Basic UPDATE

Replace the first query with this much shorter and more efficient single UPDATE command:

UPDATE features
SET   (x1,x2,x3,x4,x5,x6, y)   
    = ((x1 - g.avg1) / g.range1
     , (x2 - g.avg2) / g.range2
 --  , (x3 - ...
     , (y  - g.avgy) / g.rangey)
FROM (
   SELECT avg(x1) AS avg1, max(x1) - min(x1) AS range1
        , avg(x2) AS avg2, max(x2) - min(x2) AS range2
     -- , avg(x3) ...
        , avg(y) AS avgy, max(y) - min(y) AS rangey
   FROM   features
   ) g;

关于简短的UPDATE语法:

• SQL更新字段从另一个表的字段中提取一个表

在更简单的查询的基础上，以下是任意数量列的动态函数:

Building on the simpler query, here is a dynamic function for any number of columns:

CREATE OR REPLACE FUNCTION scale_function_dyn()
  RETURNS void AS
$func$
DECLARE
   cols text;  -- list of target columns
   vals text;  -- list of values to insert
   aggs text;  -- column list for aggregate query
BEGIN
   SELECT INTO cols, vals, aggs
          string_agg(quote_ident(attname), ', ')
        , string_agg(format('(%I - g.%I) / g.%I'
                          , attname, 'avg_' || attname, 'range_' || attname), ', ')
        , string_agg(format('avg(%1$I) AS %2$I, max(%1$I) - min(%1$I) AS %3$I'
                          , attname, 'avg_' || attname, 'range_' || attname), ', ')
   FROM   pg_attribute
   WHERE  attrelid = 'features'::regclass
   AND    attname NOT IN ('n', 'x0')  -- exclude columns from update
   AND    NOT attisdropped            -- no dropped (dead) columns
   AND    attnum > 0;                 -- no system columns

   EXECUTE format('UPDATE features
                   SET   (%s) = (%s)
                   FROM  (SELECT %s FROM features) g'
                 , cols, vals, aggs);

END
$func$  LANGUAGE plpgsql;

相关答案以及更多说明:

Related answer with more explanation:

• 更新触发器函数中的多列在plpgsql中

SQL提琴.