具有嵌套 IF 的 Postgres 函数

Question

我有一个功能，我正在尝试创建一个用户，将用户插入到 table 中，如果提供，则将用户添加到一个角色中。我可以创建用户并将它们添加到我用第一个函数创建的 table 中，但我不能有条件地将它们添加到组中。我想要选择不将用户添加到角色或包含角色并将该角色授予用户。这是我创建有效用户的函数

CREATE OR REPLACE FUNCTION create_user(
    new_user character varying,
    temp_password character varying,
    grant_role text default NULL)
  RETURNS text AS
$BODY$
BEGIN
   IF NOT EXISTS (SELECT usename FROM pg_catalog.pg_user
        Where  usename not in ('postgres','repl','pgpool')
        and usename = new_user) THEN
        EXECUTE format('CREATE USER ' || new_user || ' with password ''' || temp_password || ''';');
        EXECUTE format('insert into open_sesame (user_name, last_change_date, next_change_date) VALUES( '''  || new_user || ''',
        date(now()),
        date(now() + interval ''1 days''));');
        RETURN 'CREATED ROLE';
   ELSE
        RETURN format('ROLE ''%I'' ALREADY EXISTS', new_user);
END IF;
END;
$BODY$
  LANGUAGE plpgsql VOLATILE SECURITY DEFINER
  COST 100;
ALTER FUNCTION create_user(character varying, character varying)
  OWNER TO postgres;

我想做这样的伪代码

    BEGIN
               IF NOT EXISTS (SELECT usename FROM pg_catalog.pg_user
                    Where  usename not in ('postgres','repl','pgpool')
                    and usename = new_user) 
           && IF NOT EXISTS (SELECT rolname FROM pg_roles WHERE rolname = grant_role and rolname <> 'postgres') 
           && grant_role IS NOT NULL THEN
               EXECUTE format('CREATE USER ' || new_user || ' with password ''' || temp_password || ''';');
               EXECUTE format('GRANT ' || grant_role || ' to ' || new_user ||';');
               EXECUTE format('insert into open_sesame (user_name, last_change_date, next_change_date) VALUES( '''  || new_user || ''', date(now()), date(now() + interval ''1 days''));');
   RETURN 'CREATED USER WITH ROLE';
               ELSE 
           IF NOT EXISTS (SELECT usename FROM pg_catalog.pg_user
        Where  usename not in ('postgres','repl','pgpool')
        and usename = new_user)
                EXECUTE format('CREATE USER ' || new_user || ' with password ''' || temp_password || ''';');
                EXECUTE format('insert into open_sesame (user_name, last_change_date, next_change_date) VALUES( '''  || new_user || ''', date(now()),date(now() + interval ''1 days''));');
    RETURN 'CREATED USER ONLY';
                  ELSE
    RETURN 'NO USER CREATED';  
            END IF;
    END IF;
        END;

非常感谢任何帮助。

Answer 1

您缺少嵌套 ELSEIF 的条件。在我添加注释行的地方填充它，它应该可以按预期使用嵌套

IF ... THEN ... [ELSEIF ...] [ELSE ...] END IF;

代码：

BEGIN
 IF NOT EXISTS (
  SELECT usename 
  FROM pg_catalog.pg_user
  WHERE usename not in ('postgres','repl','pgpool')
    AND usename = new_user
  ) 
  THEN
    IF NOT EXISTS (
      SELECT rolname 
      FROM pg_roles 
      WHERE rolname = grant_role
        AND rolname <> 'postgres'
    ) AND grant_role IS NOT NULL 
    THEN
      EXECUTE format('CREATE USER ' || new_user || ' with password ''' || temp_password || ''';');
      EXECUTE format('GRANT ' || grant_role || ' to ' || new_user ||';');
      EXECUTE format('insert into open_sesame (user_name, last_change_date, next_change_date) VALUES( '''  || new_user || ''', date(now()), date(now() + interval ''1 days''));');
      RETURN 'CREATED USER WITH ROLE';
    ELSEIF -- you forgot to specify the condition
      EXECUTE format('CREATE USER ' || new_user || ' with password ''' || temp_password || ''';');
      EXECUTE format('insert into open_sesame (user_name, last_change_date, next_change_date) VALUES( '''  || new_user || ''', date(now()),date(now() + interval ''1 days''));');
      RETURN 'CREATED USER ONLY';
    ELSE
      RETURN 'NO USER CREATED';  
    END IF;
  ELSE
    RETURN format('ROLE ''%I'' ALREADY EXISTS', new_user);
  END IF;
END;

Answer 2

我最终将@Kamil G. 的答案修改为以下函数。他的回答让我到达了我需要去的地方。

CREATE OR REPLACE FUNCTION create_user(
    new_user character varying,
    temp_password character varying,
    grant_role text default NULL)
  RETURNS text AS
$BODY$
BEGIN
    IF NOT EXISTS (
        SELECT usename
        FROM pg_catalog.pg_user
        WHERE usename not in ('postgres','repl','pgpool')
        AND usename = new_user
        ) AND grant_role IS NOT NULL
    THEN
        IF EXISTS (
            SELECT rolname
            FROM pg_roles
            WHERE rolname = grant_role
            AND rolname <> 'postgres'
        )
        THEN
            EXECUTE format('CREATE USER ' || new_user || ' with password ''' || temp_password || ''';');
            EXECUTE format('GRANT ' || grant_role || ' to ' || new_user ||';');
            EXECUTE format('insert into open_sesame (user_name, last_change_date, next_change_date) VALUES( '''  || new_user || ''', date(now()), date(now() + interval ''1 days''));');
            RETURN 'CREATED USER WITH ROLE';
        ELSE
            RETURN 'NO USER CREATED';
        END IF;
    ELSEIF NOT EXISTS (
            SELECT rolname
            FROM pg_roles
            WHERE rolname = grant_role
            AND rolname <> 'postgres'
        ) AND grant_role IS NULL
    THEN
        EXECUTE format('CREATE USER ' || new_user || ' with password ''' || temp_password || ''';');
        EXECUTE format('insert into open_sesame (user_name, last_change_date, next_change_date) VALUES( '''  || new_user || ''', date(now()),date(now() + interval ''1 days''));');
        RETURN 'CREATED USER ONLY';
    ELSE
        RETURN 'NO USER CREATED';
    END IF;
END;

具有嵌套 IF 的 Postgres 函数

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postgresql-9.5