测试表如下：

/* Navicat Premium Data Transfer Source Server         :  Source Server Type    : MySQL Source Server Version : 50717 Source Host           : localhost:3306 Source Schema         : ceshi Target Server Type    : MySQL Target Server Version : 50717 File Encoding         : 65001 Date: 19/07/2019 15:08:52*/SET NAMES utf8mb4;SET FOREIGN_KEY_CHECKS = 0;-- ------------------------------ Table structure for infojson-- ----------------------------DROP TABLE IF EXISTS `infojson`;CREATE TABLE `infojson`  (  `id` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,  `info` json NULL,  PRIMARY KEY (`id`) USING BTREE) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;-- ------------------------------ Records of infojson-- ----------------------------INSERT INTO `infojson` VALUES ('1', '{\"sex\": \"male\", \"username\": \"wangermazi\"}');SET FOREIGN_KEY_CHECKS = 1;

• 获取infojson表中username的值，查询方法有：

select infojson.id, json_extract(infojson.info, '$.username') as username from infojson;

结果如下：

id   username    1   "wangermazi"

• 以上这条sql查出的username的值是带有双引号的，但是有时我们不需要双引号，此时就需要用到下面这种方式：

select infojson.id, infojson.info ->> '$.username' as username from infojson;

结果如下：

id   username    1   wangermazi