如何在Java中使用预处理语句进行select查询? [英] How to use prepared statement for select query in Java?
本文介绍了如何在Java中使用预处理语句进行select查询?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我曾多次尝试使用预处理语句,但它返回SQL异常。这是我的代码:
I had tried several times using prepared statements but it returns SQL exception. here is my code:
public ArrayList<String> name(String mobile, String password) {
ArrayList<String> getdata = new ArrayList<String>();
PreparedStatement stmt = null;
try {
String login = "select mobile, password from tbl_1 join tbl_2 on tbl_1.fk_id=2.Pk_ID where mobile=? and password=?";
String data = "select * from tbl_2 where password='" + password + "'";
PreparedStatement preparedStatement = conn.prepareStatement(login);
preparedStatement.setString(1, mobile);
preparedStatement.setString(1, password);
ResultSet rs = preparedStatement.executeQuery(login);
Statement stmts = (Statement) conn.createStatement();
if (rs.next()) {
System.out.println("Db inside RS");
ResultSet data = stmts.executeQuery(data);
while (data.next()) { /* looping through the resultset */
getdata.add(data.getString("name"));
getdata.add(data.getString("place"));
getdata.add(data.getString("age"));
getdata.add(data.getString("job"));
}
}
} catch (Exception e) {
System.out.println(e);
}
return getdata;
}
运行时,我得到以下SQL异常:
While running this, I got the following SQL exception:
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 '? and password=?' at line 1.
有任何建议使这项工作?
任何一段代码都表示赞赏。
Any suggestion to make this work? any piece of code is appreciated.
推荐答案
您需要使用:
preparedStatement.executeQuery();
而不是
preparedStatement.executeQuery(login);
将字符串传递给 executeQuery()
查询是按字面执行的,因此?
会发送到数据库,然后数据库会创建错误。通过传递查询字符串,您不会执行为其传递值的缓存预准备语句。
when you pass in a string to executeQuery()
that query is executed literally and thus the ?
is send to the database which then creates the error. By passing query string you are not execution the "cached" prepared statement for which you passed the values.
这篇关于如何在Java中使用预处理语句进行select查询?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文