postgresql 在 PL/pgSQL 中迭代 integer[]
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Iterating over integer[] in PL/pgSQL
提问by Dipro Sen
I am trying to loop through an integer array (integer[]) in a plpgsql function. Something like this:
我正在尝试integer[]在 plpgsql 函数中遍历整数数组 ( )。像这样的东西：
declare
a integer[] = array[1,2,3];
i bigint;
begin
for i in a
loop
raise notice "% ",i;
end loop;
return true;
end
In my actual use case the integer array ais passed as parameter to the function. I get this error:
在我的实际用例中，整数数组a作为参数传递给函数。我收到此错误：
ERROR: syntax error at or near "" LINE 1:
ERROR: syntax error at or near "" LINE 1:
How to loop through the array properly?
如何正确循环数组？
回答by Erwin Brandstetter
DO
$do$
DECLARE
a integer[] := array[1,2,3];
i integer; -- int, not bigint!
BEGIN
FOR i IN 1 .. array_upper(a, 1)
LOOP
RAISE NOTICE '%', a[i]; -- single quotes!
END LOOP;
END
$do$;
Or simpler with FOREACHin PostgreSQL 9.1 or later:
或者FOREACH在 PostgreSQL 9.1 或更高版本中更简单：
FOREACH i IN ARRAY a
LOOP
RAISE NOTICE '%', i;
END LOOP;
For multi-dimensional arrays see:
对于多维数组，请参见：
However, set-based solutions with generate_series()or unnest()are often faster than looping for big sets. Basic examples:
然而，使用generate_series()or的基于集合的解决方案unnest()通常比大集合的循环更快。基本示例：
Search the tags generate-seriesor unnestfor more.
搜索标签generate-series或unnest以获取更多信息。
