搞懂隔离级别

创建表t_test如下：
CREATE TABLE t_test (
id varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT ‘主键’,
name varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT ‘姓名’,
age int DEFAULT NULL COMMENT ‘年龄’,
sex varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT ‘性别’,
PRIMARY KEY (id) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC COMMENT=‘测试表’;