java.sql.SQLException参数索引超出范围（1>参数个数，为0）

问题描述

验证我选择的选择组合框后，我无法将其插入我的数据库中。 Tomcat给出以下错误：

After validation of select combo box which I have selected and I am not able to insert it in my database. Tomcat gives following error:

这是怎么造成的，如何解决？

How is this caused and how can I solve it?

推荐答案

当您在 PreparedStatement setXxx（）方法时，您将收到此错误c>，而SQL查询字符串没有任何占位符？。

You will get this error when you call any of the setXxx() methods on PreparedStatement, while the SQL query string does not have any placeholders ? for this.

例如，错误：

String sql = "INSERT INTO tablename (col1, col2, col3) VALUES (val1, val2, val3)";
// ...

preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, val1); // Fail.
preparedStatement.setString(2, val2);
preparedStatement.setString(3, val3);

您需要相应地修复SQL查询字符串以指定占位符。

You need to fix the SQL query string accordingly to specify the placeholders.

String sql = "INSERT INTO tablename (col1, col2, col3) VALUES (?, ?, ?)";
// ...

preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, val1);
preparedStatement.setString(2, val2);
preparedStatement.setString(3, val3);

注意参数索引以 1 开头，你做不需要引用这些占位符，如下所示：

Note the parameter index starts with 1 and that you do not need to quote those placeholders like so:

String sql = "INSERT INTO tablename (col1, col2, col3) VALUES ('?', '?', '?')";

否则你仍然会得到相同的异常，因为SQL解析器会将它们解释为实际的字符串值因此无法找到占位符。

Otherwise you will still get the same exception, because the SQL parser will then interpret them as the actual string values and thus can't find the placeholders anymore.

• JDBC tutorial - prepared statements

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