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How to create a unique index on a NULL column?
I am using SQL Server 2005. I want to constrain the values in a column to be unique, while allowing NULLS.
4 Answers
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Extracting hours from a DateTime (SQL Server 2005)
...omoting lazy shorthand that leads to confusion or worse. See #6 here blogs.sqlsentry.com/aaronbertrand/… and sqlblog.com/blogs/aaron_bertrand/archive/2011/09/20/…
– Aaron Bertrand
Oct 6 '14 at 19:44
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What is the equivalent of bigint in C#?
...t am I supposed to use when handling a value in C#, which is bigint for an SQL Server database?
10 Answers
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What's wrong with nullable columns in composite primary keys?
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In Sql Server a unique constraint that has a nullable column, allows the value 'null' in that column only once (given identical values for the other columns of the constraint). So such a unique constraint essentially behaves lik...
大单融资后，MOOC去哪儿 - 资讯 - 清泛网 - 专注C/C++及内核技术
...是其必然的发展方向。
“海外的大学已经通过MOOC提供了包括AP课程、本科、硕士、博士等在内的所有教育体系，目前清华大学也已经提供了二学位、MBA和硕士教育的课程学习。”张有明表示，“高等教育在任何国家都是由国家...
How do I set a column value to NULL in SQL Server Management Studio?
...rtcut is specific to SSMS (and its predecessor, Enterprise Manager). Azure SQL Server features are all built in an entirely new interface on the web.
– TylerH
2 days ago
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Run PostgreSQL queries from the command line
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psql -U username -d mydatabase -c 'SELECT * FROM mytable'
If you're new to postgresql and unfamiliar with using the command line tool psql then there is some confusing behaviour you should be aware of when you've entered an i...
SQL WHERE condition is not equal to?
...le of times.. but it didn't seem to work until I realized that DELETE in MySQL does not use the * ..
– Frank Vilea
May 27 '11 at 19:59
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SQL Group By with an Order By
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In all versions of MySQL, simply alias the aggregate in the SELECT list, and order by the alias:
SELECT COUNT(id) AS theCount, `Tag` from `images-tags`
GROUP BY `Tag`
ORDER BY theCount DESC
LIMIT 20
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Difference between scaling horizontally and vertically for databases [closed]
I have come across many NoSQL databases and SQL databases. There are varying parameters to measure the strength and weaknesses of these databases and scalability is one of them. What is the difference between horizontally and vertically scaling these databases?
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