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

2022-01-30 00:00:00 mysql jdbc java

在验证了我选择的选择组合框后，我无法将其插入我的数据库中.Tomcat 报错:

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:

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

java.sql.SQLException: Parameter index out of range (1 > number of parameters, which is 0).

这是怎么引起的，我该如何解决?

How is this caused and how can I solve it?

推荐答案

当你在 PreparedStatement 上调用任何 setXxx() 方法时，你会得到这个错误，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.

例如这是错误:

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，并且您确实不需要需要像这样引用这些占位符:

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 ('?', '?', '?')";

否则您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，因此无法再找到占位符.

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.

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