在尝试将数据插入MySQL时出错

I'm using below code to do checking before data get inserted into MySQL. However, I get error as below

在数据插入到MySQL之前，我使用下面的代码进行检查。但是，我得到如下所示的错误

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE NOT EXISTS (SELECT * FROM movie_title WHERE title = 'ABC')' at line 1
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)

Here my code

在这里我的代码

public void checkAndAdd(String movieTitle) throws Exception {
        // TODO Auto-generated method stub
        DatabaseConnection db=new DatabaseConnection();
        Connection connect=db.getConnection();
        String sql="INSERT INTO movie_title(title) VALUES (?) WHERE NOT EXISTS (SELECT * FROM movie_title WHERE title = ?)";
        PreparedStatement ps=connect.prepareStatement(sql);
        ps.setString(1,movieTitle);
        ps.setString(2,movieTitle);
        ps.executeUpdate();
        connect.close();
        ps.close(); 

    }

Edited

编辑

String sql=" IF NOT EXISTS(SELECT * FROM movie_title WHERE title = ?) INSERT INTO movie_title (title) VALUES (?) ";

1 个解决方案

#1

You can't put a WHERE clause in your SQL when you're using the VALUES keyword. Try something like this:

当使用值关键字时，不能在SQL中放置WHERE子句。试试这样:

IF NOT EXISTS(SELECT 1 FROM movie_title WHERE title = ?)
    INSERT INTO movie_title (title)
    VALUES (?)

I work with SQL Server mostly, so I'm not sure if that's completely valid for MySQL, but it will be something similar.

我主要使用SQL Server，所以我不确定这对MySQL是否完全有效，但它将是类似的。

Okay, for MySQL it has to be a little different:

对MySQL来说，它必须有点不同:

INSERT INTO movie_title (title)
SELECT mt.title
FROM
    (SELECT ? title) mt
WHERE NOT EXISTS (
    SELECT 1 FROM movie_title WHERE title = ?)

#1