MySQL 根据某一个或者多个字段查找重复数据

阿暴.

于 2023-01-05 17:48:14 发布

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文章标签： mysql

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本文链接：https://blog.youkuaiyun.com/m0_73757009/article/details/128567750

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本文介绍了如何在MySQL中检查并处理重复数据的问题。通过创建和查询特定SQL，找到并删除同一用户在同一年同一个月内的多余记录。同时，文章还演示了如何删除旧的联合索引并添加唯一索引，确保数据的唯一性。最后，提供了一种强制查询主库的方法，以避免因主从库同步延迟导致的问题。

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创表 SQL

CREATE TABLE `stat_order_count` (

`id` bigint NOT NULL AUTO_INCREMENT COMMENT 'id',

`user_id` bigint NOT NULL DEFAULT '0' COMMENT '用户id',

`year` int NOT NULL DEFAULT '0' COMMENT '年',

`month` int NOT NULL DEFAULT '0' COMMENT '月',

`order_count` int NOT NULL DEFAULT '0' COMMENT '记工次数',

`order_amount` decimal(32,4) NOT NULL DEFAULT '0.0000' COMMENT '记工金额',

`record_date` date NOT NULL DEFAULT '1970-01-01' COMMENT '记工归属月(YYYY-MM-DD,其中DD必须为01)',

`create_at` datetime(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3) COMMENT '创建时间',

`update_at` datetime(3) NOT NULL DEFAULT CURRE

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2201_76111389: package love; import java.applet.Applet; import java.awt.Color; import java.awt.Graphics; import java.net.URL; import java.util.Random; /** * 烟花 * @author enjoy * */ @SuppressWarnings("serial") public class Q extends Applet implements Runnable { public int speed, variability, Max_Number, Max_Energy, Max_Patch, Max_Length, G; public String sound; private int width, height; private Thread thread = null; private BeaClassDemo bcd[]; public void init() { int i; this.setSize(1900, 900); width = getSize().width - 1; height = getSize().height - 1; speed = 1; // 烟花绽放的速度 variability = 10; Max_Number = 980; // 可发出烟花的最大数目 Max_Energy = width + 50; Max_Patch = 90; // 最大的斑点数 Max_Length = 90; // 斑点的最大距离 G = 150; // 向地面弯曲的力度 bcd = new BeaClassDemo[Max_Number]; for (i = 0; i < Max_Number; i++) bcd[i] = new BeaClassDemo(width, height, G); } public void start() { if (thread == null) { thread = new Thread(this); thread.start(); } } @SuppressWarnings("deprecation") public void stop() { if (thread != null) { thread.stop(); thread = null; } } @SuppressWarnings({ "unused", "static-access" }) public void run() { int i; int E = (int) (Math.random() * Max_Energy * 3 / 4) + Max_Energy / 4 + 1; int P = (int) (Math.random() * Max_Patch * 3 / 4) // 烟花的斑点数 + Max_Patch / 4 + 1; int L = (int) (Math.random() * Max_Length * 3 / 4) // 烟花可发射出的距离 + Max_Length / 4 + 1; long S = (long) (Math.random() * 10000); boolean sleep; Graphics g = getGraphics(); URL u = null; while (true) { try { thread.sleep(1000 / speed); } catch (InterruptedException x) { } sleep = true; for (i = 0; i < Max_Number; i++) sleep = sleep && bcd[i].sleep; if (sleep && Math.random() * 100 < variability) { E = (int) (Math.random() * Max_Energy * 3 / 4) + Max_Energy / 4 + 1; P = (int) (Math.random() * Max_Patch * 3 / 4) + Max_Patch / 4 + 1; L = (int) (Math.random() * Max_Length * 3 / 4) + Max_Length / 4 + 1; S = (long) (Math.random() * 10000); } for (i = 0; i < Max_Number; i++) { if (bcd[i].sleep && Math.random() * Max_Number * L < 1) { bcd[i].init(E, P, L, S); bcd[i].start(); } bcd[i].show(g); } } } public void paint(Graphics g) { g.setColor(Color.black); g.fillRect(0, 0, width + 1, height + 1); } } class BeaClassDemo { public boolean sleep = true; private int energy, patch, length, width, height, G, Xx, Xy, Ex[], Ey[], x, y, Red, Blue, Green, t; private Random random; public BeaClassDemo(int a, int b, int g) { width = a; height = b; G = g; } public void init(int e, int p, int l, long seed) { int i; energy = e; patch = p; length = l; // 创建一个带种子的随机数生成器 random = new Random(seed); Ex = new int[patch]; Ey = new int[patch]; Red = (int) (random.nextDouble() * 128) + 128; Blue = (int) (random.nextDouble() * 128) + 128; Green = (int) (random.nextDouble() * 128) + 128; Xx = (int) (Math.random() * width / 2) + width / 4; Xy = (int) (Math.random() * height / 2) + height / 4; for (i = 0; i < patch; i++) { Ex[i] = (int) (Math.random() * energy) - energy / 2; Ey[i] = (int) (Math.random() * energy * 7 / 8) - energy / 8; } } public void start() { t = 0; sleep = false; } public void show(Graphics g) { if (!sleep) if (t < length) { int i, c; double s; Color color; c = (int) (random.nextDouble() * 64) - 32 + Red; if (c >= 0 && c < 256) Red = c; c = (int) (random.nextDouble() * 64) - 32 + Blue; if (c >= 0 && c < 256) Blue = c; c = (int) (random.nextDouble() * 64) - 32 + Green; if (c >= 0 && c < 256) Green = c; color = new Color(Red, Blue, Green); for (i = 0; i < patch; i++) { s = (double) t / 100; x = (int) (Ex[i] * s); y = (int) (Ey[i] * s - G * s * s); g.setColor(color); g.drawLine(Xx + x, Xy - y, Xx + x, Xy - y); if (t >= length / 2) { int j; for (j = 0; j < 2; j++) { s = (double) ((t - length / 2) * 2 + j) / 100; x = (int) (Ex[i] * s); y = (int) (Ey[i] * s - G * s * s); g.setColor(Color.black); g.drawLine(Xx + x, Xy - y, Xx + x, Xy - y); } } } t++; } else { sleep = true; } } }
JDBC.
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