不存在代碼的錯誤 - mariaDB

Question

我不確定為什么：

INSERT INTO $db.further_assess (taskid) VALUES ('id')
            WHERE NOT EXISTS (SELECT * FROM $db.further_assess where taskid='$id')

給我這個錯誤：

You have an error in your SQL syntax; check the manual that corresponds to 
your MariaDB server version for the right syntax to use near 'WHERE NOT 
EXISTS (SELECT 1 FROM risk_assessment.further_assess where taskid='222' at line 2

遵循這一點： 如果行不存在，則 Sql 插入

更新：

我的，現在正確，查詢：

        INSERT INTO $db.further_assess (taskid, reportid)
         SELECT '$id', '$report_id'
         FROM (SELECT 1) as dummytable
         WHERE NOT EXISTS (SELECT * FROM $db.further_assess where taskid='$id');

Answer 1

INSERT 語句沒有 WHERE 子句。 如果要運行條件 INSERT 語句，可以使用帶有虛擬表的 INSERT-SELECT 語句：

INSERT INTO $db.further_assess (taskid) 
   SELECT 'id'
   FROM (SELECT 1) as dummytable
   WHERE NOT EXISTS (SELECT * FROM $db.further_assess where taskid='$id')

Answer 2

做起來更簡單（也更快）

INSERT IGNORE  INTO $db.further_assess
    (taskid)
    VALUES
    ('$id')