Question

我有以下postgresql函数：

CREATE OR REPLACE FUNCTION insert_address() RETURNS TRIGGER AS
$BODY$

DECLARE row_count INTEGER;
DECLARE max_id INTEGER;
DECLARE key_ INTEGER;

BEGIN
SELECT count(*) FROM ADDRESS INTO row_count;

IF row_count = 0
THEN SET NEW.id_address = 1;
ELSE SELECT count(table_name)
 FROM FREE_KEYS
 WHERE table_name = 'ADDRESS' INTO row_count;

 IF row_count = 0 
 THEN SELECT max(id_address) FROM ADDRESS INTO max_id;
      SET NEW.id_address = max_id + 1;

 ELSE SELECT min(free_key) FROM FREE_KEYS WHERE table_name = 'ADDRESS' INTO key_;
      SET NEW.id_address = key_;
      DELETE FROM FREE_KEYS WHERE table_name = 'ADDRESS' AND free_key = key_;
 END IF;
END IF;
END;
$BODY$ LANGUAGE plpgsql;

我不明白为什么赋值操作会返回以下错误：

ERROR:  syntax error at or near "+"
LINE 700:        SET NEW.id_address = max_id + 1;

Answer 1

您的功能中有两个主要错误：

PL / pgSQL中没有SET。使用:=
变量的INTO子句必须位于SELECT语句中的列列之后。

CREATE OR REPLACE FUNCTION insert_address() RETURNS TRIGGER AS
$BODY$

DECLARE row_count INTEGER;
DECLARE max_id INTEGER;
DECLARE key_ INTEGER;

BEGIN
  SELECT count(*) 
      INTO row_count --<< the INTO has to be after the column list
  FROM ADDRESS;

  IF row_count = 0
  THEN 
    NEW.id_address := 1;  --<< there is no SET in PL/pgSQL
  ELSE 
    SELECT count(table_name)
      INTO row_count   --<< the INTO has to be after the column list
    FROM FREE_KEYS
    WHERE table_name = 'ADDRESS';

    IF row_count = 0 
    THEN 
      SELECT max(id_address) 
         INTO max_id  --<< the INTO has to be after the column list
      FROM ADDRESS;

      NEW.id_address := max_id + 1;
    ELSE 
      SELECT min(free_key) 
         INTO key_    --<< the INTO has to be after the column list
      FROM FREE_KEYS 
      WHERE table_name = 'ADDRESS';

      NEW.id_address := key_;
      DELETE FROM FREE_KEYS WHERE table_name = 'ADDRESS' AND free_key = key_;

    END IF;
  END IF;

END;
$BODY$ LANGUAGE plpgsql;

但最大的问题是功能本身。这在具有多个并发事务的环境中不起作用。你不能生成＆＃34;使用select max()的新ID除非您为每个插入锁定整个表，否则它将无法工作。

Answer 2

感谢您的帮助，对我有用。我试图在每个表上使用触发器来管理主键。我有一个名为FREE_KEYS的表，其中包含从表中删除的所有主键，以使它们可以重复用于下一次插入。但正如你所说的并发交易，它可能无法正常工作。

Postgresql语法错误在“+”或附近

2 个答案: