SQL中的ORDER BY语句——南大通用GBase 8s单表排序技巧
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">原文链接：https://www.gbase.cn/community/post/3862</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">更加多</span>精彩内容<span style="color: black;">都在</span>南大通用GBase技术社区（https://www.gbase.cn/community），南大通用致力于<span style="color: black;">作为</span>用户最信赖的数据库<span style="color: black;">制品</span>供应商。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">在数据库<span style="color: black;">查找</span>中，排序是一个<span style="color: black;">平常</span>的需求。SQL<span style="color: black;">供给</span>了强大的排序功能，<span style="color: black;">经过</span>ORDER BY语句，<span style="color: black;">咱们</span><span style="color: black;">能够</span><span style="color: black;">容易</span>地对<span style="color: black;">查找</span>结果进行排序。本文将<span style="color: black;">仔细</span>介绍南大通用GBase 8s<span style="color: black;">怎样</span><span style="color: black;">运用</span>ORDER BY语句对单表数据进行排序，并<span style="color: black;">供给</span><span style="color: black;">有些</span>实用的技巧。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">排序是数据分析和报告中不可或缺的部分。SQL`ORDER BY语句<span style="color: black;">准许</span><span style="color: black;">咱们</span><span style="color: black;">按照</span>一个或多个列对<span style="color: black;">查找</span>结果进行排序，以满足<span style="color: black;">区别</span>的数据展示需求。ORDER BY是SQL<span style="color: black;">查找</span>语句的一个子句，它<span style="color: black;">位置于</span>WHERE 子句之后，用于指定<span style="color: black;">查找</span>结果的排序<span style="color: black;">次序</span>。基本语法如下：</p>SELECT column1, column2, ...FROM table_nameORDER BY column1 , column2 , ...;<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">这儿</span>，ASC<span style="color: black;">表率</span>升序，DESC<span style="color: black;">表率</span>降序。<span style="color: black;">倘若</span>不指定排序<span style="color: black;">次序</span>，默认为升序。</p>单列排序：最简单的排序是<span style="color: black;">根据</span>单一列进行。例如，<span style="color: black;">倘若</span><span style="color: black;">咱们</span>想要<span style="color: black;">根据</span>年龄对用户信息进行排序，<span style="color: black;">能够</span><span style="color: black;">运用</span>如下SQL语句：SELECT * FROM t_user ORDER BY c_age;<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">这将返回所有用户信息，按年龄升序<span style="color: black;">摆列</span>。</p>多列排序：在某些<span style="color: black;">状况</span>下，<span style="color: black;">咱们</span>可能<span style="color: black;">必须</span><span style="color: black;">按照</span>多个列进行排序。例如，<span style="color: black;">首要</span>按年龄降序，<span style="color: black;">而后</span>按姓名升序：SELECT * FROM t_user ORDER BY c_age DESC, c_name ASC;<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">这般</span>，<span style="color: black;">查找</span>结果<span style="color: black;">首要</span>会<span style="color: black;">按照</span>年龄降序<span style="color: black;">摆列</span>，年龄相同的记录则<span style="color: black;">根据</span>姓名升序<span style="color: black;">摆列</span>。</p><span style="color: black;">运用</span>函数进行排序<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">ORDER BY不仅<span style="color: black;">能够</span>直接<span style="color: black;">运用</span>列名，还<span style="color: black;">能够</span><span style="color: black;">运用</span>SQL函数。例如，<span style="color: black;">倘若</span><span style="color: black;">咱们</span>想要<span style="color: black;">按照</span>字符串长度进行排序：</p>SELECT * FROM t_user ORDER BY LENGTH(c_name);<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">这将<span style="color: black;">按照</span>姓名的长度对用户信息进行排序。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">接下来<span style="color: black;">咱们</span>在南大通用GBase 8s中进行应用测试。</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;"><span style="color: black;">第1</span>步、创建测试表</strong></p>create table t_user(c_id serial primary key, --IDc_name varchar(20), --姓名c_age int,c_sex char(3), --性别c_cardno char(20), --身份证c_birthday char(10), --出生日期c_phone char(11), --手机号c_address1 varchar(255), --联系<span style="color: black;">位置</span>1c_address2 lvarchar(255) --联系<span style="color: black;">位置</span>2);<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;">第二步、生成测试数据</strong></p>sh gendata.sh 100000>t_user.unl#!/bin/sh#gendata.shfor i in `seq $1`doxing="赵钱孙李周吴郑王冯陈褚卫蒋沈韩杨朱秦尤许何吕施张孔曹严华金魏陶姜戚谢邹喻柏水窦章云苏潘葛奚范彭郎鲁韦昌马苗凤花方俞任袁柳酆鲍史唐"num=$((RANDOM % ${#xing}))ming="靖铭琛川承司斯宗骁聪在钩锦铎楚铮钦则女宝宝宜用字真心新悦西兮楚初千锐素锦静镜斯舒瑜童楠景茗聿启尧言嘉桉桐筒竹林乔栋家翊松楠景茗聿启尧言嘉桉桐筒竹林乔栋家翊松清澈泫浚润泽向凡文浦洲珩玄洋淮雨子云妍澜淇沐潆盈雨文冰雯溪子云汐潞淇妙涵卓昱南晨知宁年易晗炎焕哲煦旭明阳朗典灿夏珞煊晴彤诺宁恬钧灵昭琉晨曦南毓冉辰宸野安为<span style="color: black;">也</span>围岚<span style="color: black;">亦</span>以延允容恩衡宇硕已意<span style="color: black;">亦</span>坤辰伊米安恩以容宛岚又衣亚悠允画"num1=$((RANDOM % ${#ming}))num2=$((RANDOM % ${#ming}))age=$(( $RANDOM % (99)))xingbies="男女"xingbie=$((RANDOM % ${#xingbies}))random_day=$((RANDOM % (36500)))target_timestamp=$((random_day * 86400))random_date=$(date -d @$target_timestamp "+%Y-%m-%d")addr=`openssl rand - 100`echo "0|"${xing:$num:1}${ming:$num1:1}${ming:$num2:1}"|"$age"|"${xingbies:$xingbie:1}"|"$(openssl rand - 10 |cksum |cut -c1-8)$(openssl rand - 10 |cksum |cut -c1-9)"|"$random_date"|139"$(openssl rand - 10 |cksum |cut -c1-8)"|"$addr"|"$addr"|"done<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;">第三步、导入数据</strong></p>echo "load from t_user.unl insert into t_user;" |dbaccess testdb<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;">第四步、查看测试SQL及结果</strong></p><p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="//q2.itc.cn/images01/20240618/4c324ca9ba3c473e8e2e431061c68b82.png" style="width: 50%; margin-bottom: 20px;"></p><p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;"><span style="color: black;">重视</span>事项</strong></p><p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">以下场景<span style="color: black;">没法</span>避免排序：1、sort字段中有不在索引里的字段2、sort字段<span style="color: black;">次序</span>与索引字段<span style="color: black;">次序</span>不一致3、多个表的字段排序</p><p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">经过</span>本文的介绍，您应该对SQL中的ORDER BY语句有了更深入的理解。排序是SQL<span style="color: black;">查找</span>中一个非常实用的功能，能够让<span style="color: black;">咱们</span>以更直观的方式查看和分析数据。<span style="color: black;">期盼</span>本文能够<span style="color: black;">帮忙</span>您更有效地<span style="color: black;">运用</span>ORDER BY进行数据排序。</p><p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">原文链接：https://www.gbase.cn/community/post/3862</p><p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">更加多</span>精彩内容<span style="color: black;">都在</span>南大通用GBase技术社区（https://www.gbase.cn/community），南大通用致力于<span style="color: black;">作为</span>用户最信赖的数据库<span style="color: black;">制品</span>供应商。<a style="color: black;"><span style="color: black;">返回<span style="color: black;">外链论坛：www.fok120.com</span>，查看<span style="color: black;">更加多</span></span></a></p>
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