PostgreSQL检查表是否存在，抛出“关系不存在”错误

SELECT EXISTS (
   SELECT 1
   FROM   pg_tables
   WHERE  schemaname = 'public'
   AND    tablename = 'your_table_name'
);

SELECT EXISTS (
   SELECT 1
   FROM   information_schema.tables
   WHERE  table_schema = 'public'
   AND    table_name = 'your_table_name'
);

DROP TABLE IF EXISTS your_table_name;

CREATE OR REPLACE FUNCTION check_table_exists(table_name text)
  RETURNS boolean AS
$$
DECLARE
  table_exists boolean;
BEGIN
  SELECT EXISTS (
    SELECT 1
    FROM   pg_tables
    WHERE  schemaname = 'public'
    AND    tablename = table_name
  ) INTO table_exists;

  IF NOT table_exists THEN
    RAISE EXCEPTION 'Table % does not exist', table_name;
  END IF;

  RETURN table_exists;
END;
$$
LANGUAGE plpgsql;