将这句代码改为以pointname查询条件sql

可以将代码修改为如下形式：

String sql = "SELECT * FROM FY_YDL_POLLUTION_INFO WHERE 1=1";
if(pointname != null && !pointname.isEmpty()) {
    sql += " AND POINTNAME LIKE '%" + pointname + "%'";
}

这样修改后，如果pointname不为null且不为空字符串，就会添加一个以POINTNAME为查询条件的SQL查询语句。如果pointname为null或空字符串，则不添加该查询条件。最终生成的SQL查询语句将查询FY_YDL_POLLUTION_INFO表中所有POINTNAME列包含指定字符串pointname的行。

相关问题

使用多线程在50w数据表alarm_point中提取id(String)，dev_name(String)两个字段，然后根据id将dev_name的数据更新至字段alm_class_desc(String)中，数据库为clickhouse，输出sql语句，使用java完成

您可以参考以下Java代码实现：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class UpdateAlarmClassDesc {

    private static final String URL = "jdbc:clickhouse://localhost:8123/database";
    private static final String USERNAME = "username";
    private static final String PASSWORD = "password";
    private static final String SELECT_SQL = "SELECT id, dev_name FROM alarm_point";
    private static final String UPDATE_SQL = "UPDATE alarm_point SET alm_class_desc = ? WHERE id = ?";

    public static void main(String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(10);
        try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
             PreparedStatement selectStmt = conn.prepareStatement(SELECT_SQL);
             ResultSet rs = selectStmt.executeQuery()) {
            while (rs.next()) {
                String id = rs.getString("id");
                String devName = rs.getString("dev_name");
                executorService.submit(() -> updateAlarmClassDesc(conn, id, devName));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            executorService.shutdown();
        }
    }

    private static void updateAlarmClassDesc(Connection conn, String id, String devName) {
        try (PreparedStatement updateStmt = conn.prepareStatement(UPDATE_SQL)) {
            updateStmt.setString(1, devName);
            updateStmt.setString(2, id);
            updateStmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

这段代码使用Java的多线程技术，从clickhouse数据库的`alarm_point`表中提取`id`和`dev_name`字段，并使用`id`更新`alm_class_desc`字段。可以根据需要修改线程池的大小和数据库连接信息。

帐号表结构如下： CREATE TABLE `t_account` ( `account_id` int(10) unsigned NOT NULL auto_increment COMMENT '所属帐号id', `account_name` varchar(50) NOT NULL COMMENT '帐号名', `password` varchar(16) NOT NULL COMMENT '密码', `last_login_time` timestamp NOT NULL default '1979-01-01 00:00:00' COMMENT '最后登录时间', `point` int(10) unsigned NOT NULL default '0' COMMENT '积分', PRIMARY KEY USING BTREE (`account_id`), ) ENGINE=InnoDB AUTO_INCREMENT=10001 DEFAULT CHARSET=utf8; CREATE TABLE `t_account_nickname` ( `account_id` int(10) unsigned NOT NULL COMMENT '所属帐号id', `account_nickname `varchar(50) NOT NULL COMMENT'昵称', PRIMARY KEY USING BTREE (`account_id`), ) ENGINE=InnoDB DEFAULT CHARSET=utf8; 请写出SQL语句（温馨提示：列点作答，字体端正，代码细节与规范） 1.查询最近1000个登录的帐号（mysql） 2.查询如下结果：第一列帐号ID，第二列帐号名，第三列昵称，第四列积分 3.对帐号名里包含rock的帐号，积分修改为0 4.查询出重复的昵称

1. 查询最近1000个登录的帐号（mysql）

SELECT account_id, account_name, last_login_time, point 
FROM t_account 
ORDER BY last_login_time DESC 
LIMIT 1000;

2. 查询如下结果：第一列帐号ID，第二列帐号名，第三列昵称，第四列积分

SELECT t1.account_id, t1.account_name, t2.account_nickname, t1.point 
FROM t_account AS t1 
LEFT JOIN t_account_nickname AS t2 ON t1.account_id = t2.account_id;

3. 对帐号名里包含rock的帐号，积分修改为0

UPDATE t_account 
SET point = 0 
WHERE account_name LIKE '%rock%';

4. 查询出重复的昵称

SELECT account_nickname, COUNT(*) AS num 
FROM t_account_nickname 
GROUP BY account_nickname 
HAVING num > 1;