请尝试以下语法：

CREATE OR REPLACE FUNCTION update_table_log_received()
RETURNS TRIGGER AS $$
DECLARE
  added_column TEXT;
  target_table_name TEXT;
  old_column text;
BEGIN
  -- Check if a new column has been added
  IF (TG_OP = 'INSERT') THEN
    added_column := new."column_name";
    target_table_name := new."table_name";
  END IF;

  if not exists(select 1 from information_schema."columns" where table_name = target_table_name and column_name = added_column) 
  then 
      EXECUTE 'ALTER TABLE items.' || LOWER(target_table_name)|| ' ADD COLUMN ' || LOWER(added_column) || ' VARCHAR(50)';
  end if; 
  
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

我试过我的DB这是工程。你可以改变一些细节自己。

已修复;问题应为：

• 如何在postgresql函数中选择表和表列。

参考文件：How to add column if not exists on PostgreSQL?
如何检查给定模式中是否存在表
How to get a list column names and datatypes of a table in PostgreSQL?
基本上，information_schema只能由所有者访问，即用户或（i）查询时看到结果，但在脚本内部执行时返回FALSE更多详细信息，请单击此处：https://stackoverflow.com/a/24089729/15170264
为安全起见，在使用CTE修复后完全触发以查询pg_catalog，还在我的执行查询中添加了ADD COLUMN IF NOT EXISTS

CREATE OR REPLACE FUNCTION update_table_log_received()
RETURNS TRIGGER AS $$
DECLARE
  added_column TEXT;
  target_table_name TEXT;
  old_column varchar;
    old_table varchar;
BEGIN
  -- Check if a new column has been added
  IF (TG_OP = 'INSERT') THEN
    added_column := NEW."COLUMN_NAME";
    target_table_name := NEW."TABLE_NAME";
  END IF;
 /*
  * --------------- --CTE to find Columns of table "Target_table_name" from pg_catalog
  */

    WITH cte_tables AS (
   SELECT
    pg_attribute.attname AS column_name,
    pg_catalog.format_type(pg_attribute.atttypid, pg_attribute.atttypmod) AS data_type
FROM
    pg_catalog.pg_attribute
INNER JOIN
    pg_catalog.pg_class ON pg_class.oid = pg_attribute.attrelid
INNER JOIN
    pg_catalog.pg_namespace ON pg_namespace.oid = pg_class.relnamespace
WHERE
    pg_attribute.attnum > 0
    AND NOT pg_attribute.attisdropped
    AND pg_namespace.nspname = 'items'
    AND pg_class.relname = 'trace'
ORDER BY
    attnum ASC
)
select column_name into old_column from cte_tables where 
column_name=LOWER(added_column);

 
  if (old_column is null )  then 
    -- Add the new column to the target table
        old_column := added_column;
        EXECUTE 'ALTER TABLE items.' || LOWER(target_table_name)|| ' ADD COLUMN IF NOT EXISTS ' || LOWER(added_column) || ' VARCHAR(50)';
    else
        old_column := added_column || 'already exists ! ';
  END IF;
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

create TRIGGER update_table_log_received_trigger
AFTER INSERT
ON items."TABLE_LOG_RECEIVED"
FOR EACH ROW
EXECUTE FUNCTION update_table_log_received();

变量old_column存储else条件消息，但不返回它，如果它是一个简单的函数，则会返回它。