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ALTER DATABASE failed because a lock could not be placed on database
...t the problem has occurred elsewhere.
http://www.geakeit.co.uk/2010/12/11/sql-take-offline-fails-alter-database-failed-because-a-lock-could-not-error-5061/
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What are the best practices for using a GUID as a primary key, specifically regarding performance?
...ly recommend not to do is use the GUID column as the clustering key, which SQL Server does by default, unless you specifically tell it not to.
You really need to keep two issues apart:
the primary key is a logical construct - one of the candidate keys that uniquely and reliably identifies every r...
Linux下部署企业级邮件服务器(postfix + dovecot + extmail) - 开源 & Gith...
...原理：
当用户通过extmail登陆时，首先extmail先去通过mysql进行虚拟用户认证，当认证通过时，postfix通过Cyrus-SASL这个函数库，这个认证框架，结合Courier-authlib对发信人进行认证，通过检索Mysql数据库中的数据来进行认证，以此来...
How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
...ery frequently asked question here is how to do an upsert, which is what MySQL calls INSERT ... ON DUPLICATE UPDATE and the standard supports as part of the MERGE operation.
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Find all records which have a count of an association greater than zero
...inct.size
=> 17
[14] pry(main)> Article.joins(:comments).distinct.to_sql
=> "SELECT DISTINCT \"articles\".* FROM \"articles\" INNER JOIN \"comments\" ON \"comments\".\"article_id\" = \"articles\".\"id\""
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Search of table names
...DBName.sys.tables
WHERE Name LIKE '%XXX%'
If so, you could use dynamic SQL to add the dbname to the query:
DECLARE @DBName NVARCHAR(200) = 'YourDBName',
@TableName NVARCHAR(200) = 'SomeString';
IF NOT EXISTS (SELECT 1 FROM master.sys.databases WHERE Name = @DBName)
BEGIN
PR...
Targeting both 32bit and 64bit with Visual Studio in same solution/project
...istered in the GAC, you can also use the standard reference tags this way (SQLite as an example):
<ItemGroup Condition="'$(Platform)' == 'x86'">
<Reference Include="System.Data.SQLite, Version=1.0.80.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139, processorArchitecture=x86" />
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Select columns from result set of stored procedure
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This was interesting: sqlnerd.blogspot.com/2005/09/…
– d-_-b
Mar 4 '12 at 23:40
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Does the join order matter in SQL?
... In fact, all join types are associative, as specified by the SQL standard and according to mathematical definitions of associativity, but they don't appear associative because rearranging the parentheses requires moving the ON clause (i.e. the "join specification") to a new location. T...
SQLite add Primary Key
I created a table in Sqlite by using the CREATE TABLE AS syntax to create a table based on a SELECT statement. Now this table has no primary key but I would like to add one.
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