操纵ORDER BY [英] manipulating ORDER BY
问题描述
你好，
我有一张桌子，说
----------
ID | myvalue
----------
1 | B
2 | C
3 | A
4 | A
5 | B
6 | C
- --------
是否可以执行SELECT语句，以便输出按列myvalue排序
。由B，然后是A，然后是C？
有些像：
SELECT * FROM mytable ORDER BY myvalue（''B''，''A' '，'''C''）;
这只是一个例子，但我想知道这个原则是否可能是
。
谢谢，
巴特
Bart Van der Donck写道：你好，
我有一张桌子，说
----------
ID | myvalue
- --------
1 | B
2 | C
3 | A
4 | A
5 | B
6 | C
----------
是否可以执行SELECT语句，以便按列myvalue排序输出
。由B，然后A，然后是C？
有些像：
SELECT * FROM mytable ORDER BY myvalue（'''''，''A''，''C''） ;
一种方法是创建另一个表，在那里你告诉我们应该以什么顺序值
：
table myvalue_order
----------------------
order_number |价值
1 | B
2 | A
3 | C $ / $
----------------------
然后使用加入，比如这个：
选择mytable。*来自mytable，value_order
其中mytable.myvalue = value_order.value
by myvalue_order。 order_number;
请注意，如果使用这样的查询，则根本不显示使用
order_number的值的行。如果你想获得那些
值，你可以使用：
选择mytable。*来自mytable
左外连接mytable.myvalue = value_order.value上的value_order
by myvalue_order.order_number;
但是这会在第一个位置放置没有订单号的行。你
当然可以使用相反的订单号
table myvalue_order
------------ ----------
order_number |价值
3 | B
2 | A
1 | C $ / $
----------------------
然后再做...订单by order_number desc;
空值应该在列表的底部。
Bart Van der Donck写道：< blockquote class =post_quotes>你好，
我有一张桌子，说
----------
ID | myvalue
----------
1 | B
2 | C
3 | A
4 | A
5 | B 6 | C
----------
是否可以执行SELECT语句，以便输出按列myvalue排序。由B，然后A，然后是C？
有些像：
SELECT * FROM mytable ORDER BY myvalue（'''''，''A''，''C''） ;
一种方法是创建另一个表，在那里你告诉我们应该以什么顺序值
：
table myvalue_order
----------------------
order_number |价值
1 | B
2 | A
3 | C $ / $
----------------------
然后使用加入，比如这个：
选择mytable。*来自mytable，value_order
其中mytable.myvalue = value_order.value
by myvalue_order。 order_number;
请注意，如果使用这样的查询，则根本不显示使用
order_number的值的行。如果你想获得那些
值，你可以使用：
选择mytable。*来自mytable
左外连接mytable.myvalue = value_order.value上的value_order
by myvalue_order.order_number;
但是这会在第一个位置放置没有订单号的行。你
当然可以使用相反的订单号
table myvalue_order
------------ ----------
order_number |价值
3 | B
2 | A
1 | C $ / $
----------------------
然后再做...订单by order_number desc;
空值应位于列表的底部。
" Bart Van der Donck" < BA ** @ nijlen.com>在消息中写道
ID | myvalue
----------
1 | B
2 | C
3 | A
4 | A
5 | B
6 | C
----------
是否有可能执行一个SELECT语句，以便输出按列myvalue排序。 by B，然后是A，然后是C？
是否
SELECT * FROM mytable ORDER BY if（myvalue ='' A'，2，......）;
工作？
Hello,
I have a table, say
----------
ID|myvalue
----------
1|B
2|C
3|A
4|A
5|B
6|C
----------
Is it possible to perform a SELECT statement so that the output gets
ordered by column "myvalue" by B, then A, then C ?
Someting like:
SELECT * FROM mytable ORDER BY myvalue(''B'',''A'',''C'');
This is only an example of course but I wonder if this principle were
possible.
thanks,
Bart
Bart Van der Donck wrote:Hello,
I have a table, say
----------
ID|myvalue
----------
1|B
2|C
3|A
4|A
5|B
6|C
----------
Is it possible to perform a SELECT statement so that the output gets
ordered by column "myvalue" by B, then A, then C ?
Someting like:
SELECT * FROM mytable ORDER BY myvalue(''B'',''A'',''C'');
One way is to create another table, where you tell in what order values
should be:
table myvalue_order
----------------------
order_number | value
1 | B
2 | A
3 | C
----------------------
And then use a join, like this:
select mytable.* from mytable, value_order
where mytable.myvalue=value_order.value
order by myvalue_order.order_number;
Note that if a query like this is used, then rows where value with
order_number is used, are not displayed at all. If you want to get those
values also, you could use:
select mytable.* from mytable
left outer join value_order on mytable.myvalue=value_order.value
order by myvalue_order.order_number;
But this would place rows without order number at the first place. You
could of course use opposite order numbers
table myvalue_order
----------------------
order_number | value
3 | B
2 | A
1 | C
----------------------
And then do ... order by order_number desc;
And null values should be at the bottom of the list.
Bart Van der Donck wrote:Hello,
I have a table, say
----------
ID|myvalue
----------
1|B
2|C
3|A
4|A
5|B
6|C
----------
Is it possible to perform a SELECT statement so that the output gets
ordered by column "myvalue" by B, then A, then C ?
Someting like:
SELECT * FROM mytable ORDER BY myvalue(''B'',''A'',''C'');
One way is to create another table, where you tell in what order values
should be:
table myvalue_order
----------------------
order_number | value
1 | B
2 | A
3 | C
----------------------
And then use a join, like this:
select mytable.* from mytable, value_order
where mytable.myvalue=value_order.value
order by myvalue_order.order_number;
Note that if a query like this is used, then rows where value with
order_number is used, are not displayed at all. If you want to get those
values also, you could use:
select mytable.* from mytable
left outer join value_order on mytable.myvalue=value_order.value
order by myvalue_order.order_number;
But this would place rows without order number at the first place. You
could of course use opposite order numbers
table myvalue_order
----------------------
order_number | value
3 | B
2 | A
1 | C
----------------------
And then do ... order by order_number desc;
And null values should be at the bottom of the list.
"Bart Van der Donck" <ba**@nijlen.com> wrote in message
ID|myvalue
----------
1|B
2|C
3|A
4|A
5|B
6|C
----------
Is it possible to perform a SELECT statement so that the output gets
ordered by column "myvalue" by B, then A, then C ?
Does
SELECT * FROM mytable ORDER BY if(myvalue=''A'', 2, ...);
work?
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