PostgreSQL:错误运算符不存在：| |字符变化

我需要使用string_agg（）函数检查函数中的条件，并需要将其分配给变量。赋值后，我需要执行带有值的变量

示例：

create or replace function funct1(a int,b varchar)
returns void as
$$
declare
        wrclause varchar := '';
        sqlq varchar ;
        t varchar;
begin
     IF (b IS NOT NULL ) THEN 
        wrclause := 'AND b IN ('|| b || ')';
     END IF;


     sqlq := string_agg('select *, abcd as "D" from ' ||table_namess,' Union all ') as namess
     from tablescollection2 ud
     inner join INFORMATION_SCHEMA.Tables so on ud.table_namess = so.Table_name
     WHERE cola NOT IN (SELECT cola FROM tablet WHERE colb = || a  ||) || wrclause; /* Error occurred here at  = || a */

     raise info '%',sqlq;

     execute sqlq into t;

     raise info '%',t;
end;
$$
language plpgsql;

select funct1(1,'1,2,3');

ERROR:  operator does not exist: || integer

调用函数：

create or replace function funct1(a int,b varchar)
returns void as
$$
declare
        wrclause varchar := '';
        sqlq varchar ;
        t varchar;
begin
     IF (b IS NOT NULL ) THEN 
        wrclause := 'AND b IN ('|| b || ')';
     END IF;


     sqlq := string_agg('select *, abcd as "D" from ' ||table_namess,' Union all ') as namess
     from tablescollection2 ud
     inner join INFORMATION_SCHEMA.Tables so on ud.table_namess = so.Table_name
     WHERE cola NOT IN (SELECT cola FROM tablet WHERE colb = || a  ||) || wrclause; /* Error occurred here at  = || a */

     raise info '%',sqlq;

     execute sqlq into t;

     raise info '%',t;
end;
$$
language plpgsql;

select funct1(1,'1,2,3');

ERROR:  operator does not exist: || integer

错误：

create or replace function funct1(a int,b varchar)
returns void as
$$
declare
        wrclause varchar := '';
        sqlq varchar ;
        t varchar;
begin
     IF (b IS NOT NULL ) THEN 
        wrclause := 'AND b IN ('|| b || ')';
     END IF;


     sqlq := string_agg('select *, abcd as "D" from ' ||table_namess,' Union all ') as namess
     from tablescollection2 ud
     inner join INFORMATION_SCHEMA.Tables so on ud.table_namess = so.Table_name
     WHERE cola NOT IN (SELECT cola FROM tablet WHERE colb = || a  ||) || wrclause; /* Error occurred here at  = || a */

     raise info '%',sqlq;

     execute sqlq into t;

     raise info '%',t;
end;
$$
language plpgsql;

select funct1(1,'1,2,3');

ERROR:  operator does not exist: || integer

---

|

是一个用于链接两段文本的操作符，它要求在操作符前后都有文本（或可转换为文本的内容），如下所示：

select 'a' || 'b'
select 'a' || 3

因此，虽然这些似乎是有效的：

wrclause := 'AND b IN ('|| b || ')';
sqlq := string_agg('select *, abcd as "D" from ' ||table_namess,' Union all ') as namess

这绝对不是：

WHERE cola NOT IN (SELECT cola FROM tablet WHERE colb = || a  ||) || wrclause;

你想在这里实现什么

看起来您可能正在尝试动态构造查询。您需要记住，您不能将自由文本与SQL混合，并期望Postgres对其进行排序，没有任何编程或查询语言可以做到这一点

如果这是您的意图，那么您应该首先完整地构造查询字符串（在变量中），然后使用它调用

EXECUTE

，以对其进行解释

看看这些：

---

这篇文章包含语法错误

... IN (SELECT cola FROM tablet WHERE colb = || a  ||) || ...

PostgreSQL可以理解这一点，但会尝试搜索一元前缀（和后缀）

|

运算符，默认情况下它们不存在（但是，错误消息说，情况并非如此）

编辑：

create or replace function funct1(a int,b varchar)
returns void as
$$
declare
        wrclause varchar := '';
        sqlq varchar ;
        t varchar;
begin
     IF (b IS NOT NULL ) THEN 
        wrclause := 'AND b IN ('|| b || ')';
     END IF;


     sqlq := string_agg('select *, abcd as "D" from ' ||table_namess,' Union all ') as namess
     from tablescollection2 ud
     inner join INFORMATION_SCHEMA.Tables so on ud.table_namess = so.Table_name
     WHERE cola NOT IN (SELECT cola FROM tablet WHERE colb = || a  ||) || wrclause; /* Error occurred here at  = || a */

     raise info '%',sqlq;

     execute sqlq into t;

     raise info '%',t;
end;
$$
language plpgsql;

select funct1(1,'1,2,3');

ERROR:  operator does not exist: || integer

F.ex。这些是数字上的有效（预定义）一元运算符：

SELECT |/ 25.0, -- prefix, square root, result: 5.0
       5 !,     -- postfix, factorial, result: 120,
       @ -5,    -- prefix, absolute, result: 5
       @ -5 !;  -- mixed, result: 120

---

对我想知道原因？非常感谢你的帮助。