mysql 左表为null_关于使用leftjoin左表值为null的原因咨询

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我是靠谱客的博主仁爱苗条，最近开发中收集的这篇文章主要介绍mysql 左表为null_关于使用leftjoin左表值为null的原因咨询，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

Navicat Premium Data Transfer

Source Server : 本地

Source Server Type : MySQL

Source Server Version : 50726

Source Host : localhost:3306

Source Schema : test

Target Server Type : MySQL

Target Server Version : 50726

File Encoding : 65001

Date: 21/11/2020 20:09:15

SET NAMES utf8mb4;

SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------

-- Table structure for cardetail

-- ----------------------------

DROP TABLE IF EXISTS `cardetail`;

CREATE TABLE `cardetail` (

`id` int(10) NOT NULL AUTO_INCREMENT,

`cars_model` varchar(30) DEFAULT NULL,

`contact` varchar(150) DEFAULT NULL,

`classify` varchar(10) DEFAULT NULL,

`cars_turbine` varchar(30) DEFAULT NULL,

`upkeep_date` varchar(20) DEFAULT NULL,

`isvideo` varchar(4) DEFAULT NULL,

`mobile` varchar(30) DEFAULT NULL,

`setup_year` varchar(50) DEFAULT NULL,

`videopic` varchar(255) DEFAULT NULL,

`uid` varchar(50) DEFAULT NULL,

`sticky` varchar(30) DEFAULT NULL,

`biz_url` varchar(255) DEFAULT NULL,

`oli_wear` varchar(10) DEFAULT NULL,

`pic_side` varchar(255) DEFAULT NULL,

`jiage` varchar(10) DEFAULT NULL,

`pic_trail` varchar(255) DEFAULT NULL,

`qujian` varchar(20) DEFAULT NULL,

`video` varchar(255) DEFAULT NULL,

`biz_info` text,

`cars_year` varchar(20) DEFAULT NULL,

`brands` varchar(20) DEFAULT NULL,

`vendor_name` varchar(255) DEFAULT NULL,

`pic_frontrow` text,

`cars_type` varchar(30) DEFAULT NULL,

`created` varchar(30) DEFAULT NULL,

`rego_date` varchar(20) DEFAULT NULL,

`cretID` varchar(100) DEFAULT NULL,

`totaltimes` varchar(100) DEFAULT NULL,

`title` varchar(255) DEFAULT NULL,

`photo` text,

`buysell` varchar(10) DEFAULT NULL,

`iplocation` varchar(100) DEFAULT NULL,

`email` varchar(100) DEFAULT NULL,

`air_nums` varchar(100) DEFAULT NULL,

`zhengshu` varchar(255) DEFAULT NULL,

`highlight` varchar(100) DEFAULT NULL,

`pic_backrow` text,

`aboutme` text,

`global_placa` varchar(20) DEFAULT NULL,

`keep_nums` varchar(10) DEFAULT NULL,

`totalcount` varchar(20) DEFAULT NULL,

`cars_color` varchar(30) DEFAULT NULL,

`milltime` varchar(30) DEFAULT NULL,

`cars_status` varchar(30) DEFAULT NULL,

`gasoline_type` varchar(30) DEFAULT NULL,

`pic_front` text,

`tags` varchar(255) DEFAULT NULL,

`telephone` varchar(255) DEFAULT NULL,

`nianfen` varchar(20) DEFAULT NULL,

`versionlog` varchar(20) DEFAULT NULL,

`biz_addr` varchar(255) DEFAULT NULL,

`weixin` varchar(100) DEFAULT NULL,

`pic_engine` text,

`qq` varchar(15) DEFAULT NULL,

`comment` varchar(10) DEFAULT NULL,

`status` varchar(3) DEFAULT NULL,

`pic_zcontrol` text,

`gearbox` varchar(10) DEFAULT NULL,

`comm_nums` varchar(10) DEFAULT NULL,

`cars_tag` varchar(255) DEFAULT NULL,

`mileage` varchar(20) DEFAULT NULL,

`drive_mode` varchar(30) DEFAULT NULL,

`displacement` varchar(30) DEFAULT NULL,

`carid` varchar(30) DEFAULT NULL,

`changed` varchar(30) DEFAULT NULL,

`uptitle` varchar(255) DEFAULT NULL,

`path` varchar(255) DEFAULT NULL,

`domainUrl` varchar(255) DEFAULT NULL,

`report_total` varchar(10) DEFAULT NULL,

`iskeep` varchar(10) DEFAULT NULL,

`topicMsg` varchar(255) DEFAULT NULL,

`nickyname` varchar(255) DEFAULT NULL,

`gender` varchar(10) DEFAULT NULL,

`userphoto` text,

`useraboutme` varchar(255) DEFAULT NULL,

`contact_nums` varchar(30) DEFAULT NULL,

`vitem` varchar(10) DEFAULT NULL,

`role` varchar(10) DEFAULT NULL,

`userstatus` varchar(2) DEFAULT NULL,

`usercreated` varchar(20) DEFAULT NULL,

`level_id` varchar(3) DEFAULT NULL,

`reportbynums` varchar(10) DEFAULT NULL,

`post_nums` varchar(10) DEFAULT NULL,

`isclose` int(1) DEFAULT '0',

PRIMARY KEY (`id`)

) ENGINE=InnoDB AUTO_INCREMENT=41 DEFAULT CHARSET=utf8mb4;

-- ----------------------------

-- Records of cardetail

-- ----------------------------

BEGIN;

INSERT INTO `cardetail` VALUES (39, '1558337909', '测试', '172', '1558428120', '2020-09', '0', '157777', '', 'https://', '91917302420019', '0', '', '1558428080', 'https://', '58500', 'https://', '1560234117', '', '', '2018', '268', '', 'https://', '1558427776', '1600650432', '过期', '', '729', '准新车宝马2018 ', 'https://', '102', 'AUd', '@.com', '1558427990', '', '0', 'https://', '2018年宝马', '3793', '4', '827', '1558429830', '1605079320837', '1558427736', '1558427910', 'https://', '', '', '2018', '1042', '', 'ddddd', 'https://', '', '2', '1', 'https://', '262', '1', '1558428140,1558428190,1558428180', '27329', '1558427954', '1558427880', '142039140032006', '1605874352', '准新车宝马', '', '', '0', '0', '', 'jk', '259', 'https://', '', '22', '0', '10', '1', '1556030420', '7', '0', '5', 0);

COMMIT;

-- ----------------------------

-- Table structure for carlist

-- ----------------------------

DROP TABLE IF EXISTS `carlist`;

CREATE TABLE `carlist` (

`id` int(10) NOT NULL AUTO_INCREMENT,

`postid` varchar(50) DEFAULT NULL,

`classify` varchar(20) DEFAULT NULL,

`domainid` varchar(10) DEFAULT NULL,

`isvideo` varchar(5) DEFAULT NULL,

`buysell` varchar(10) DEFAULT NULL,

`source` varchar(10) DEFAULT NULL,

`nianfen` varchar(20) DEFAULT NULL,

`jiage` varchar(20) DEFAULT NULL,

`title` varchar(255) DEFAULT NULL,

`mileage` varchar(100) DEFAULT NULL,

`videopic` text,

`setupyear` varchar(255) DEFAULT NULL,

`photo` text,

`carstag` varchar(255) DEFAULT NULL,

`status` varchar(5) DEFAULT NULL,

`changed` varchar(20) DEFAULT NULL,

`openyear` varchar(20) DEFAULT NULL,

`showtype` varchar(3) DEFAULT NULL,

`createtime` varchar(20) DEFAULT NULL,

`isnew` int(1) DEFAULT '1',

`favorite` int(1) DEFAULT '0',

`favorite_time` varchar(50) DEFAULT NULL,

`isclose` int(1) unsigned DEFAULT '0',

PRIMARY KEY (`id`)

) ENGINE=InnoDB AUTO_INCREMENT=45 DEFAULT CHARSET=utf8mb4;

-- ----------------------------

-- Records of carlist

-- ----------------------------

BEGIN;

INSERT INTO `carlist` VALUES (44, '142039140032006', '172', '2113', '0', '102', '64', '2016', '29000', 'Lexus ', '65000公里', 'https://', '', 'https:', '1558428160,1558428170,1558428180', '1', '1604589743', '', '0', '2020-11-08 13:03:35', 0, 0, NULL, 0);

COMMIT;

SET FOREIGN_KEY_CHECKS = 1;

您好，这是我做测试的sql