Sqlite 查询问题
好吧，所以我正在尝试将数据存储在 Sqlite 中。所以我试图用“line”来存储用户的id。然而，where 子句似乎让我失望了。
String query = "SELECT * FROM Users WHERE username='Fellixombc";
ResultSet result = this.sqlStatement.executeQuery(query);
int userId = 0;
while(result.next()) {
System.out.println("TRUE");
userId = result.getInt("id");
System.out.println(result.getString("username"));
}
真正的不是印刷。然而，如果我从查询中删除 WHERE 子句，它会打印出所有用户名/id，当然还有“TRUE”。
我是否遗漏了 Sqlite 及其语法的某些内容？
编辑：只是为了澄清“用户”列中有一个 id 为 1、用户名为 Fellixombc 的用户 编辑：所以我接受了你的建议并尝试准备声明，现在是我的代码：
PreparedStatement sqlStatement = this.sqlConnection.prepareStatement("SELECT * FROM Users WHERE username=?");
sqlStatement.setString(1, "Fellixombc");
ResultSet result = sqlStatement.executeQuery();
int userId = 0;
while(result.next()) {
System.out.println("TRUE");
userId = result.getInt("id");
System.out.println(result.getString("username"));
}
result.close();
Alright, so I'm trying to store data in Sqlite. So I'm trying to store the id of the user with the a "line". Yet, it seems that the where clause is failing me.
String query = "SELECT * FROM Users WHERE username='Fellixombc";
ResultSet result = this.sqlStatement.executeQuery(query);
int userId = 0;
while(result.next()) {
System.out.println("TRUE");
userId = result.getInt("id");
System.out.println(result.getString("username"));
}
And true is not printing. Yet, if I remove the WHERE clause from the query, it will print out all of the usernames/id's fine, and of course "TRUE".
Am I missing something with Sqlite and it's syntax?
edit: Just to clarify there is a user in the Users column with the id of 1 and with the username Fellixombc
edit: So I took your guy's suggestion and tried prepare statement, heres my code now:
PreparedStatement sqlStatement = this.sqlConnection.prepareStatement("SELECT * FROM Users WHERE username=?");
sqlStatement.setString(1, "Fellixombc");
ResultSet result = sqlStatement.executeQuery();
int userId = 0;
while(result.next()) {
System.out.println("TRUE");
userId = result.getInt("id");
System.out.println(result.getString("username"));
}
result.close();
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本质上，您想存储用户名，对吗？
您当前的查询将检索与用户名相关的所有信息。这就是 SELECT 查询的作用，它进行检索。
如果您需要创建新用户，请使用：
我应该告诉您，您可能需要在此查询中提供更多信息，具体取决于您的用户表具有哪些其他字段。
编辑：
在您的选择语句中，您有一个开放的单引号。
为了
避免 SQL 注入问题，请考虑 prepareStatement 函数。
Essentially, you want to store the username, correct?
Your current query will retrieve all information on relative to a username. It's what a SELECT query does, it retrieves.
If you need to create a new user, use:
I should tell you that you might need to provide more information in this query, depending on what other fields your Users table has.
EDIT:
In your select statement, you have an open single quote.
should be
To avoid issues with SQL injection, consider the prepareStatement function.
尝试修剪您的用户名字段。数据中的某个位置可能存在虚假空间，导致您的 where 子句失败。
另外，同意@MPelletier。您绝对应该使用PreparedStatements。
Try doing a trim on your username field. Its possible there's a spurious space somewhere in the data thats causing your where clause to fail.
Also, agree with @MPelletier. You should definitely be using PreparedStatements.