MySQL 如何在SQL中选择每个交替行并按降序显示？

为了获取每个交替行，请在WHERE下使用MOD()。然后使用ORDER BY DESC将结果以降序显示−

select *from yourTableName where mod(yourColumnName,2)=1 order by yourColumnName DESC;

让我们首先创建一个表−

mysql> create table DemoTable
(
    UniqueId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
    ClientName varchar(40),
    ClientAge int
);
Query OK, 0 rows affected (1.02 sec)

使用insert命令在表中插入一些记录−

mysql> insert into DemoTable(ClientName,ClientAge) values('Chris',34);
Query OK, 1 row affected (0.47 sec)
mysql> insert into DemoTable(ClientName,ClientAge) values('Tom',45);
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable(ClientName,ClientAge) values('Sam',36);
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable(ClientName,ClientAge) values('Carol',42);
Query OK, 1 row affected (0.25 sec)
mysql> insert into DemoTable(ClientName,ClientAge) values('David',38);
Query OK, 1 row affected (0.12 sec)

使用select语句显示表中的所有记录−

mysql> select *from DemoTable;

这将产生以下输出−

+----------+------------+-----------+
| UniqueId | ClientName | ClientAge |
+----------+------------+-----------+
|        1 | Chris      |        34 |
|        2 | Tom        |        45 |
|        3 | Sam        |        36 |
|        4 | Carol      |        42 |
|        5 | David      |        38 |
+----------+------------+-----------+
5 rows in set (0.00 sec)

现在，让我们选择每个交替行并按降序显示−

mysql> select *from DemoTable where mod(UniqueId,2)=1 order by UniqueId DESC;

这将产生以下输出−

+----------+------------+-----------+
| UniqueId | ClientName | ClientAge |
+----------+------------+-----------+
|        5 | David      |        38 |
|        3 | Sam        |        36 |
|        1 | Chris      |        34 |
+----------+------------+-----------+
3 rows in set (0.00 sec)

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