大约有 3,620 项符合查询结果（耗时：0.0222秒） [XML]
How do I (or can I) SELECT DISTINCT on multiple columns?
... of the currently accepted answer by factor 10 - 15 (in my tests on PostgreSQL 8.4 and 9.1).
But this is still far from optimal. Use a NOT EXISTS (anti-)semi-join for even better performance. EXISTS is standard SQL, has been around forever (at least since PostgreSQL 7.2, long before this question w...
How do we count rows using older versions of Hibernate (~2009)?
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What's the point of using an ORM if we end up coding SQL anyway?
– thermz
Apr 17 '12 at 15:35
Th...
nullable object must have a value
...on methods (e.g. Select, Where), the lambda function might be converted to SQL that might not behave identically to your C# code. For instance, C#'s short-circuit evaluated && and || are converted to SQL's eager AND and OR. This can cause problems when you're checking for null in your lambda...
.gitignore for Visual Studio Projects and Solutions
....build.csdef
# Windows Store app package directory
AppPackages/
# Others
sql/
*.Cache
ClientBin/
[Ss]tyle[Cc]op.*
~$*
*~
*.dbmdl
*.dbproj.schemaview
*.pfx
*.publishsettings
node_modules/
# RIA/Silverlight projects
Generated_Code/
# Backup & report files from converting an old project file
# ...
NoSQL Use Case Scenarios or WHEN to use NoSQL [closed]
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It really is an "it depends" kinda question. Some general points:
NoSQL is typically good for unstructured/"schemaless" data - usually, you don't need to explicitly define your schema up front and can just include new fields without any ceremony
NoSQL typically favours a denormalised schema d...
Increment value in mysql update query
...
You could also just do this:
mysql_query("
UPDATE member_profile
SET points = points + 1
WHERE user_id = '".$userid."'
");
share
|
improve t...
How to set a default entity property value with Hibernate
...not portable from a database to another, and you need to know the specific SQL language of your server.
– pdem
Sep 20 '16 at 7:30
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Difference between “read commited” and “repeatable read”
...le read simply reads a "snapshot" not the actual data. From the docs dev.mysql.com/doc/refman/5.0/en/…: "All consistent reads within the same transaction read the snapshot established by the first read."
– Derek Litz
Jan 17 '13 at 16:40
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How do I update if exists, insert if not (AKA “upsert” or “merge”) in MySQL?
...RT a row when it does not exist, or to UPDATE if it exists, using one MySQL query?
2 Answers
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Spring JPA @Query with LIKE
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SQL-Injection using your solution possible? (asking because of CONCAT)
– ramden
Nov 8 '18 at 11:22
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