CREATE OR REPLACE FUNCTION foo() RETURNS int AS $$
    DECLARE
      i int;
    BEGIN
      i = 0;  
      WHILE NOT i = 25 LOOP
          i = i + 1;
          i = i * i;
      END LOOP;
      RETURN i;
    END;
    $$ LANGUAGE plpgsql;

    > SELECT foo();
    25

请注意，Pl / pgsql可以清楚地区分赋值和比较，如图所示

WHILE NOT i = 25 LOOP

所以，问题是：

>我没有在文档中找到提及和/或解释这一点的一些部分？
>有没有任何已知的后果使用=而不是：=？

编辑/脚注：

请采取“更现代”的部分与眨眼像A Brief,Incomplete,and Mostly Wrong History of Programming Languages：

1970 – Niklaus Wirth creates Pascal,a procedural language. Critics
immediately denounce Pascal because it uses “x := x + y” Syntax
instead of the more familiar C-like “x = x + y”. This criticism
happens in spite of the fact that C has not yet been invented.

1972 – Dennis Ritchie invents a powerful gun that shoots both forward
and backward simultaneously. Not satisfied with the number of deaths
and permanent maimings from that invention he invents C and Unix.