MySQL 在 select 语句中生成带有循环的列

MySQL producing columns with loop in a select statement

提问by Trees4theForest

In MySQL I have a function that takes a number argument and spits out a subset of results from another table, based on that number. Implementation currently looks like:

在 MySQL 中，我有一个函数，它接受一个数字参数并根据该数字从另一个表中吐出结果的子集。实现目前看起来像：

SELECT 
  id,
  date,
  function(do stuff with value 1) as t1,
  function(do stuff with value 2) as t2,
  function(do stuff with value 3) as t3,
  ...
  function(do stuff with value N) as tN
FROM table

Can you use a loop in a select statement (or even a procedure that builds a table) so the above becomes:

您可以在 select 语句（甚至是构建表的过程）中使用循环，因此上述内容变为：

SELECT
  id,
  date,
  LOOP x = 1 through N
    function(do stuff with value x) as tx,
  END LOOP
FROM table

Thanks.

谢谢。

采纳答案by DRapp

yes you can... take a look into DynamicSQL..

是的，你可以......看看DynamicSQL..

Here's one sample

这是一个示例

and another example

另一个例子

In general, you build a string that contains the SQL statement you want to execute, then prepare it, then execute it...

通常，您构建一个包含要执行的 SQL 语句的字符串，然后准备它，然后执行它...