查询数据按字母升序进行排序(A～Z),但数据的排序并不仅限于此,还可以使用 ORDER BY 中的 DESC 对查询结果进行降序排序(Z～A)。 mysql>SELECT*FROMtb_students_infoORDERBYheight; mysql>SELECTname,heightFROMtb_students_infoORDERBYheight,name; mysql>SELECTname,heightFROMtb_student_infoORDERBYheightDESC,name...
通过使用put更新student表指定字段的数据,具体语法如下: put 1. 在student表中,将行键为1001、列名name且值为18这一条数据中的值更新成100,命令如下: hbase 1. 上述命令执行成功后,使用scan扫描数据表中的数据,扫描结果如下: hbase 1. 上述代码中,行键为1001、列名为info:name且值为18这一条数据中的值已经...
--将一列数据转化为多行但必须是数组类型 select explode(split(category,",")) from movie_info; 1. 2. 3. 实现需求 SELECT movie, category_name FROM movie_info lateral VIEW explode(split(category,",")) movie_info_tmp AS category_name; 1. 2. 3. 4. 5. 总结一下,如果只需要将某列数据转...
示例 左外连接时利用student_info表中的courseId与course_info中的courseId进行匹配,返回已经选课的学生姓名及所选的课程名称,没有匹配值的右表记录将返回NULL。 1
1、row_num() over()函数:根据某个字段排序后编号1,2,3。。 select *,ROW_NUMBER() over ( order by majorid) as num from StudentInfo s 2、rank() over(PARTITION BY 字段A order by 字段B desc ) 根据字段A分组 每组根据字段B排名(每组中字段B值相等的话排名就相等 有并列排名时,如两个第二名...
2)例如 select * from student order by id desc; 就是把选出的结果经过“按 id 从大到小排序”后,把资源返回。3)还可以 select * from student order by age desc,id desc;用“,”号隔开多个排序条件,这样,先按 age 再按 id,就是说,先按...
2)例如 select * from student order by id desc; 就是把选出的结果经过“按 id 从大到小排序”后,把资源返回。3)还可以 select * from student order by age desc,id desc;用“,”号隔开多个排序条件,这样,先按 age 再按 id,就是说,先按...
$sql ="update tblcourseinfo set coursename = '$coursename', price = '$price', desc = '$desc', duration = '$duration', avail = '$avail' where regid = $regid"; } if (!mysqli_query($link, $sql)) { echo 'Error Saving Data. ' . mysqli_error($link); ...
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This book covers the practical syllabus a student skipper needs to pass advanced sailing exams. It is also designed to be kept on board as a coaching guide covering common situations that may trip up even the most experienced skipper. It covers the practical side of yacht cruising: how to ...