java - java jdbc中如何查询字符串

Question

我遇到了异常

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 '?http://www.andhrabhoomi.net/' at line 1

我正在尝试检查我的数据库中是否存在某个字符串

我的代码:

               sql = "SELECT url FROM data where url = ?"+ "string";
                ResultSet rs = statement.executeQuery(sql);
                System.out.println(rs); 

Answer 1

由于您确实有 ? 参数标记，因此您似乎正在尝试使用 PreparedStatement，正如您应该做的那样，所有这些都假设 "string" 是在 ? 所在位置使用的实际值的经过清理的示例。

这是 PreparedStatement 应该如何完成的:

String sql = "SELECT url FROM data where url = ?";
try (PreparedStatement stmt = conn.prepareStatement(sql)) {
    stmt.setString(1, "string");
    try (ResultSet rs = stmt.executeQuery()) {
        while (rs.next()) {
            System.out.println(rs.getString("url"));
        }
    }
}