postgresql 错误：“SELECT”处或附近的语法错误
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ERROR: syntax error at or near "SELECT"
提问by Y_KL
I am really new to postgres. The question looks very simple but I just cant see where I got wrong.
我对 postgres 真的很陌生。这个问题看起来很简单，但我就是看不出哪里错了。
I a table created as follows:
我创建的表如下：
CREATE TABLE IF NOT EXISTS t(
tn VARCHAR(30) NOT NULL,
PRIMARY KEY(tn)
);
I want to insert an instance if the instance does not exist. Here is my code:
如果实例不存在，我想插入一个实例。这是我的代码：
INSERT INTO t (tn)
VALUES
(SELECT 'q' WHERE NOT EXISTS (SELECT * FROM t WHERE tn = 'q')) ;
And the psql console keeps giving me the error
并且 psql 控制台不断给我错误
ERROR: syntax error at or near "SELECT"
I have checked every piece of code individually, for instance both
我已经单独检查了每一段代码，例如
SELECT 'q' WHERE NOT EXISTS (SELECT * FROM t WHERE tn = 'q');
and
和
INSERT INTO t (tn) VALUES ('p');
run without error. But error occurs when I put them together.
运行没有错误。但是当我把它们放在一起时会发生错误。
Does anyone know where I got wrong..?
有谁知道我哪里错了..？
采纳答案by Bohemian
Lose VALUESand the brackets...
输VALUES和括号...
INSERT INTO t (tn)
SELECT 'q' WHERE NOT EXISTS (SELECT * FROM t WHERE tn = 'q');
