PL/pgSQL中的EXECUTE ... USING语句不适用于记录类型吗? [英] EXECUTE...USING statement in PL/pgSQL doesn't work with record type?

问题描述

我正在尝试在PL/PgSQL中编写一个函数，该函数必须与它作为参数接收的表一起使用.

I'm trying to write a function in PL/PgSQL that have to work with a table it receives as a parameter.

我在函数定义中使用EXECUTE..INTO..USING语句来构建动态查询(这是我知道的唯一方法)，但是...我遇到了RECORD数据类型问题.

I use EXECUTE..INTO..USING statements within the function definition to build dynamic queries (it's the only way I know to do this) but ... I encountered a problem with RECORD data types.

让我们考虑以下示例(极其简化).

Let's consider the follow (extremely simplified) example.

 -- A table with some values.
 DROP TABLE IF EXISTS table1;
 CREATE TABLE table1 (
     code INT,
     descr TEXT
 );

INSERT INTO table1 VALUES ('1','a');
INSERT INTO table1 VALUES ('2','b');


-- The function code. 
DROP FUNCTION IF EXISTS foo (TEXT);
CREATE FUNCTION foo (tbl_name TEXT) RETURNS VOID AS $$
DECLARE 
    r RECORD;
    d TEXT;
BEGIN
    FOR r IN
    EXECUTE 'SELECT * FROM ' || tbl_name
    LOOP
    --SELECT r.descr INTO d; --IT WORK
    EXECUTE 'SELECT ($1)' || '.descr' INTO d USING r; --IT DOES NOT WORK
    RAISE NOTICE '%', d;
END LOOP;

END;
$$ LANGUAGE plpgsql STRICT;

-- Call foo function on table1
SELECT foo('table1');

它输出以下错误:

错误:无法在记录数据类型中识别列"descr"

ERROR: could not identify column "descr" in record data type

尽管我使用的语法对我来说似乎是有效的.我无法使用静态选择(在示例中进行了注释)，因为我想从名称上引用列名.

although the syntax I used seems valid to me. I can't use the static select (commented in the example) because I want to dinamically refer the columns names.

所以..有人知道上面的代码有什么问题吗?

So..someone know what's wrong with the above code?

推荐答案

是的.您不能在PL/pgSQL空间之外使用类型记录.

It's true. You cannot to use type record outside PL/pgSQL space.

RECORD值仅在plpgsql中有效.

RECORD value is valid only in plpgsql.

可以做到

EXECUTE 'SELECT $1.descr' INTO d USING r::text::xx;

这篇关于PL/pgSQL中的EXECUTE ... USING语句不适用于记录类型吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！