在“IF”或附近的Postgres语法错误 [英] Postgres syntax error at or near "IF"

问题描述

我是postgres的新手，我正在完成我的任务。我不得不创建一个只有1列的表，然后我得到了这个声明在pgadmin III上运行：

I am new to postgres and I am working on an assignment of mine. I had to create a table with only 1 column and, then I was given this statement to run in on pgadmin III:

BEGIN;
INSERT INTO mytable VALUES (1);
SAVEPOINT savepoint1;
INSERT INTO mytable VALUES (2);
ROLLBACK TO SAVEPOINT savepoint1;
INSERT INTO mytable VALUES (3);
SAVEPOINT savepoint2;
INSERT INTO mytable VALUES (4);
INSERT INTO mytable VALUES (5);
SAVEPOINT savepoint3;
SELECT * FROM mytable;
--NOTE: You need to run this IF statement as PGScript 
--(button next to the normal run button)
IF (CAST ((SELECT MAX(id) FROM mytable) AS INTEGER) = 4)
BEGIN
      RELEASE SAVEPOINT savepoint2;
END
ELSE
BEGIN
      INSERT INTO mytable VALUES(6);
END
--Run the next steps normally
SAVEPOINT savepoint2;
INSERT INTO mytable VALUES (7);
RELEASE SAVEPOINT savepoint2;
INSERT INTO mytable VALUES (8);
ROLLBACK TO savepoint2;
COMMIT;

当我运行此操作时出现此错误：语法错误在IF处或附近

when I run this I get this error: syntax error at or near "IF"

我已经看过这个 38.6.2。 Conditionals38.6.2。条件，我不太了解这一点，我是否需要更改查询

I have already take a look at this 38.6.2. Conditionals38.6.2. Conditionals , I dont understand this very well, Do I need to change the query to have

IF (CAST ((SELECT MAX(id) FROM mytable) AS INTEGER) = 4) THEN 
BEGiN 

然后当它结束时我应该结束：

and then when it ends I should end it with:

END IF

为什么毕竟出现错误？

Why there is an error after all??

推荐答案

IF和其他PL / pgSQL功能仅在PL / pgSQL函数中可用。如果要使用 IF ，则需要将代码包装在函数中。如果您使用的是9.0+，那么您可以使用 DO 编写内联函数：

IF and other PL/pgSQL features are only available inside PL/pgSQL functions. You need to wrap your code in a function if you want to use IF. If you're using 9.0+ then you can do use DO to write an inline function:

do $$
begin
  -- code goes here
end
$$

如果你正在使用在早期版本的PostgreSQL中，你必须编写一个包含代码的命名函数，然后执行该函数。

If you're using an earlier version of PostgreSQL then you'll have to write a named function which contains your code and then execute that function.

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