blocks|key|2184091|text|select+*
from+table
where+DATEDIFF(day,+GETDATE(),+maildate)+=+case+when
++++DATEPART(hour,+GETDATE())+>=+16+then+1+else+0
end|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2184092|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>select *
from table
where DATEDIFF(day, GETDATE(), maildate) = case when
 DATEPART(hour, GETDATE()) &gt;= 16 then 1 else 0
end
</code></pre>

blocks|key|1163039|text|IF+datepart(hh,+getdate())+>=+16
++++BEGIN
++++++++SELECT+*
++++++++FROM+table
++++++++WHERE+DateDiff(day,+getdate(),+MailDate)+=+1
++++END
ELSE
++++BEGIN
++++++++SELECT+*
++++++++FROM+table
++++++++WHERE+DateDiff(day,+getdate(),+MailDate)+=+0
++++END|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1163040|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>IF datepart(hh, getdate()) &gt;= 16
 BEGIN
 SELECT *
 FROM table
 WHERE DateDiff(day, getdate(), MailDate) = 1
 END
ELSE
 BEGIN
 SELECT *
 FROM table
 WHERE DateDiff(day, getdate(), MailDate) = 0
 END
</code></pre>

blocks|key|219848|text|我不知道确切的MS-语法-方言，但我将尝试证明您不需要IF或CASE构造。我以@mellamokb的回复为例。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|219849|SELECT+*
++FROM+the_table
+WHERE+(+DATEPART(hour,+GETDATE())+>=+16
+++++++++++AND+DATEDIFF(day,+GETDATE(),+MailDate)+=+1)
++++OR+(DATEPART(hour,+GETDATE())+<+16
+++++++++++AND+DATEDIFF(day,+GETDATE(),+MailDate)+=+0)
+++++;+++|code-block|syntax|javascript|219850|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I don't know the exact MS-syntax-dialect, but I'll try to prove that you don't need an IF or a CASE construct. I took @mellamokb 's reply as an example.

<pre><code>SELECT *
 FROM the_table
 WHERE ( DATEPART(hour, GETDATE()) &gt;= 16
 AND DATEDIFF(day, GETDATE(), MailDate) = 1)
 OR (DATEPART(hour, GETDATE()) &lt; 16
 AND DATEDIFF(day, GETDATE(), MailDate) = 0)
 ; 
</code></pre>

blocks|key|2184124|text|这里的想法是使用隐含重写规则：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2184125|IF+(+x+)+THEN+(+y+)+++is+equivalent+to++(+NOT+(+x+)+OR+y+)|code-block|syntax|javascript|2184126|在你的情况下|2184127|IF+(+DATEPART(HOUR,+CURRENT_TIMESTAMP)+>=+16+)+
+++THEN+(+DATEDIFF(DAY,+CURRENT_TIMESTAMP,+MailDate)+=+1+)+|2184128|等同于|2184129|(+NOT+(+DATEPART(HOUR,+CURRENT_TIMESTAMP)+>=+16+)+
+++OR+(+DATEDIFF(DAY,+CURRENT_TIMESTAMP,+MailDate)+=+1+)+)+|2184130|，它本身等同于|2184131|(+(+DATEPART(HOUR,+CURRENT_TIMESTAMP)+<+16+)+
+++OR+(+DATEDIFF(DAY,+CURRENT_TIMESTAMP,+MailDate)+=+1+)+)|2184132|将原始ELSE子句重写为IF..THEN语句：|offset|length|style|CODE|2184133|IF+(+DATEPART(HOUR,+CURRENT_TIMESTAMP)+<+16+)+
+++THEN+(+DATEDIFF(DAY,+CURRENT_TIMESTAMP,+MailDate)+=+0+)+|2184134|等同于(这次省略了中间步骤)|2184135|(+(+DATEPART(HOUR,+CURRENT_TIMESTAMP)+>=+16+)
+++OR+(+DATEDIFF(DAY,+CURRENT_TIMESTAMP,+MailDate)+=+0+)+)|2184136|然后可以用合取范式(“一系列AND”)来编写这两个表达式|2184137|SELECT+*
++FROM+the_table
+WHERE+(+(+DATEPART(HOUR,+CURRENT_TIMESTAMP)+<+16+)+
++++++++++OR+(+DATEDIFF(DAY,+CURRENT_TIMESTAMP,+MailDate)+=+1+)+)+
+++++++AND+
+++++++(+(+(DATEPART(HOUR,+CURRENT_TIMESTAMP)+>=+16
++++++++++OR+(+DATEDIFF(DAY,+CURRENT_TIMESTAMP,+MailDate)+=+0+)+)++;|2184138|entityMap^0|0|0|0|0|0|0|0|0|3|4|C|8|0|0|0|0|E|3|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1C|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|1D|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|1E|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|1F|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|1G|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|1H|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1I|8|@$U|1J|V|1K|W|X]|$U|1L|V|1M|W|X]]|9|@]|A|$]]|$1|Y|3|Z|5|D|7|1N|8|@]|9|@]|A|$E|F]]|$1|10|3|11|5|6|7|1O|8|@]|9|@]|A|$]]|$1|12|3|13|5|D|7|1P|8|@]|9|@]|A|$E|F]]|$1|14|3|15|5|6|7|1Q|8|@$U|1R|V|1S|W|X]]|9|@]|A|$]]|$1|16|3|17|5|D|7|1T|8|@]|9|@]|A|$E|F]]|$1|18|3|-4|5|6|7|1U|8|@]|9|@]|A|$]]]|19|$]]

The idea here is to use the implication rewrite rule:

<pre><code>IF ( x ) THEN ( y ) is equivalent to ( NOT ( x ) OR y )
</code></pre>

In your case

<pre><code>IF ( DATEPART(HOUR, CURRENT_TIMESTAMP) &gt;= 16 ) 
 THEN ( DATEDIFF(DAY, CURRENT_TIMESTAMP, MailDate) = 1 ) 
</code></pre>

is equivalent to

<pre><code>( NOT ( DATEPART(HOUR, CURRENT_TIMESTAMP) &gt;= 16 ) 
 OR ( DATEDIFF(DAY, CURRENT_TIMESTAMP, MailDate) = 1 ) ) 
</code></pre>

and is itself equivalent to

<pre><code>( ( DATEPART(HOUR, CURRENT_TIMESTAMP) &lt; 16 ) 
 OR ( DATEDIFF(DAY, CURRENT_TIMESTAMP, MailDate) = 1 ) )
</code></pre>

Re-writing the original <code>ELSE</code> clause as an <code>IF..THEN</code> statement in its own right:

<pre><code>IF ( DATEPART(HOUR, CURRENT_TIMESTAMP) &lt; 16 ) 
 THEN ( DATEDIFF(DAY, CURRENT_TIMESTAMP, MailDate) = 0 ) 
</code></pre>

is equivalent to (this time omiting the intermediate step)

<pre><code>( ( DATEPART(HOUR, CURRENT_TIMESTAMP) &gt;= 16 )
 OR ( DATEDIFF(DAY, CURRENT_TIMESTAMP, MailDate) = 0 ) )
</code></pre>

The two expression can then be writting in conjunctive normal form ("a series of <code>AND</code>s)

<pre><code>SELECT *
 FROM the_table
 WHERE ( ( DATEPART(HOUR, CURRENT_TIMESTAMP) &lt; 16 ) 
 OR ( DATEDIFF(DAY, CURRENT_TIMESTAMP, MailDate) = 1 ) ) 
 AND 
 ( ( (DATEPART(HOUR, CURRENT_TIMESTAMP) &gt;= 16
 OR ( DATEDIFF(DAY, CURRENT_TIMESTAMP, MailDate) = 0 ) ) ;
</code></pre>

blocks|key|2184144|text|如果(a.is_+a.name+=‘t’，'Active'，'Inactive')来自mytable+a，则选择活动|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2184145|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

select a.name, if(a.is_active='t','Active','Inactive') from mytable a

blocks|key|1163019|text|在SQL中，您需要一个存储过程来完成此操作。请看一下这里的文档http://msdn.microsoft.com/en-us/library/aa174792(v=sql.80).aspx|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1163020|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/aa174792(v=sql.80).aspx^0|V|1R|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

You need a stored procedure to do this in SQL. Have a look at the docs here <a href="http://msdn.microsoft.com/en-us/library/aa174792(v=sql.80).aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/aa174792(v=sql.80).aspx</a>

blocks|key|1862282|text|IF+(+DATEDIFF(h,+GETDATE(),+DATEADD(h,4,GETDATE()))>0+)

SELECT+*
FROM+table
WHERE+MailDate+is+Tomorrow

ELSE

SELECT+*
FROM+table
WHERE+MailDate+is+Today|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1862283|这是MS+SQL。如果你想做更多的事情，只需要一个命令/select，如果你要开始...结束。|unstyled|1862284|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>IF ( DATEDIFF(h, GETDATE(), DATEADD(h,4,GETDATE()))&gt;0 )

SELECT *
FROM table
WHERE MailDate is Tomorrow

ELSE

SELECT *
FROM table
WHERE MailDate is Today
</code></pre>

This is MS SQL. If you want to do more then just one command/select inside the if you do BEGIN .... END.

blocks|key|1862332|text|IF+DATEPART(HOUR,+GETDATE())+>+16
BEGIN
++++--+SELECT+statement
END
ELSE+
BEGIN
++++--+SELECT+statement
END|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1862333|它不必在存储过程中。|unstyled|1862334|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>IF DATEPART(HOUR, GETDATE()) &gt; 16
BEGIN
 -- SELECT statement
END
ELSE 
BEGIN
 -- SELECT statement
END
</code></pre>

It does not have to be in a stored procedure.

I'm a newbie to SQL Server. Please help me to write the following Logic in a query.

<pre><code>If getnow() &gt; today 4 PM
Then
 SELECT *
 FROM table
 WHERE MailDate is Tomorrow
Else
 SELECT *
 FROM table
 WHERE MailDate is Today
</code></pre>

IF Condition in an SQL query

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我是SQL Server的新手。请帮助我在查询中写下下面的逻辑。If getnow() > today 4 PMThen    SELECT *    FROM table    WHERE MailDate is TomorrowElse    SELECT *    FROM table    WHERE MailDate is Today

问SQL查询中的IF条件
EN

回答 8

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问SQL查询中的IF条件
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