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What does inverse_of do? What SQL does it generate?
...cumentation, it seems like the :inverse_of option is a method for avoiding SQL queries, not generating them. It's a hint to ActiveRecord to use already loaded data instead of fetching it again through a relationship.
Their example:
class Dungeon < ActiveRecord::Base
has_many :traps, :inverse_...
Which SQL query is faster? Filter on Join criteria or Where clause?
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For inner joins it doesn't matter where you put your criteria. The SQL compiler will transform both into an execution plan in which the filtering occurs below the join (ie. as if the filter expressions appears is in the join condition).
Outer joins are a different matter, since the place of...
MySQL复制的概述、安装、故障、技巧、工具 - 数据库(内核) - 清泛网 - 专注...
MySQL复制的概述、安装、故障、技巧、工具同MongoDB，Redis这样的NoSQL数据库的复制相比，MySQL复制显得相当复杂！概述首先主服务器把数据变化记录到主日志，然后从服务器通过I O线...同MongoDB，Redis这样的NoSQL数据库的复制相比，M...
How to query MongoDB with “like”?
I want to query something with SQL's like query:
39 Answers
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SQL Server equivalent to MySQL enum data type?
Does SQL Server 2008 have a a data-type like MySQL's enum ?
5 Answers
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SELECT * FROM X WHERE id IN (…) with Dapper ORM
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Dapper supports this directly. For example...
string sql = "SELECT * FROM SomeTable WHERE id IN @ids"
var results = conn.Query(sql, new { ids = new[] { 1, 2, 3, 4, 5 }});
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Select n random rows from SQL Server table
I've got a SQL Server table with about 50,000 rows in it. I want to select about 5,000 of those rows at random. I've thought of a complicated way, creating a temp table with a "random number" column, copying my table into that, looping through the temp table and updating each row with RAND() , and ...
MySQL/Amazon RDS error: “you do not have SUPER privileges…”
I'm attempting to copy my mysql database from an Amazon EC2 to an RDS:
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How to truncate string using SQL server
i have large string in SQL Server. I want to truncate that string to 10 or 15 character
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How to compare only Date without Time in DateTime types in Linq to SQL with Entity Framework?
Is there a way to compare two DateTime variables in Linq2Sql but to disregard the Time part.
12 Answers
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