Sql server 关于SQL SERVER左联接和分组依据
我有两个表,Blog表有一个指向BlogTag表的FK BlogTagID列:Sql server 关于SQL SERVER左联接和分组依据,sql-server,Sql Server,我有两个表,Blog表有一个指向BlogTag表的FK BlogTagID列: BlogTagID BlogTagName 1 JAVA 2 .NET 3 PHP 博客表: BlogID BlogTagID BlogTitle 1 2 test1 2 1 test2 3 2 test3 BlogTag表:
BlogTagID BlogTagName
1 JAVA
2 .NET
3 PHP
博客表:
BlogID BlogTagID BlogTitle
1 2 test1
2 1 test2
3 2 test3
BlogTag表:
BlogTagID BlogTagName
1 JAVA
2 .NET
3 PHP
我想得到结果:
BlogTagName count
JAVA 1
.NET 2
PHP 0
如何得到这个?非常感谢 试试这段代码
select BlogTagName, count(blogid)
from BlogTag bt
left join Blog b on b.blogtagid = bt.BlogTagID
group by BlogTagName
SQL FIDDLE:请尝试以下代码
select BlogTagName, count(blogid)
from BlogTag bt
left join Blog b on b.blogtagid = bt.BlogTagID
group by BlogTagName
SQL FIDDLE:您也可以试试这个
SELECT BlogTagName,COUNT(BlogTagID) FROM Blog b JOIN BlogTagID bt WHERE b.BlogTagID=bt.BlogTagID GROUP BY BlogTagID;
你也可以试试这个
SELECT BlogTagName,COUNT(BlogTagID) FROM Blog b JOIN BlogTagID bt WHERE b.BlogTagID=bt.BlogTagID GROUP BY BlogTagID;
这是因为.net在两个博客中。。因此,它将成为两个不同的行。这是因为.net在两个博客中。。因此,它将成为两个不同的行。