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INNER JOIN ON vs WHERE clause
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It's easier to see this with the WHERE syntax.
As for your example, in MySQL (and in SQL generally) these two queries are synonyms.
Also note that MySQL also has a STRAIGHT_JOIN clause.
Using this clause, you can control the JOIN order: which table is scanned in the outer loop and which one is i...
How to add new column to MYSQL table?
I am trying to add a new column to my MYSQL table using PHP. I am unsure how to alter my table so that the new column is created. In my assessment table I have:
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MySQL OPTIMIZE all tables?
MySQL has an OPTIMIZE TABLE command which can be used to reclaim unused space in a MySQL install. Is there a way (built-in command or common stored procedure) to run this optimization for every table in the database and/or server install, or is this something you'd have to script up yourself?
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How can I define a composite primary key in SQL?
How can I define a composite primary key consisting of two fields in SQL?
3 Answers
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MySQL主从服务器数据一致性的核对与修复 - 数据库(内核) - 清泛网 - 专注C/...
MySQL主从服务器数据一致性的核对与修复我上一次遇到MySQL主从服务器数据一致性问题，想想是几年前的事情了，还依稀记得当时惊慌失措的情景，好在最后借助Maatkit解决了问题。几年...我上一次遇到MySQL主从服务器数据一致性...
How to Select Every Row Where Column Value is NOT Distinct
...e or be used in an aggregate function error. Is the only fix - editing the sql_mode?
– Volodymyr Bobyr
Jul 16 at 16:21
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How to change column datatype in SQL database without losing data
I have SQL Server database and I just realized that I can change the type of one of the columns from int to bool .
11 A...
ActiveRecord.find(array_of_ids), preserving order
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The answer is for mysql only
There is a function in mysql called FIELD()
Here is how you could use it in .find():
>> ids = [100, 1, 6]
=> [100, 1, 6]
>> WordDocument.find(ids).collect(&:id)
=> [1, 6, 100]
>> WordDoc...
What's the best strategy for unit-testing database-driven applications?
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I'm always running tests against an in-memory DB (HSQLDB or Derby) for these reasons:
It makes you think which data to keep in your test DB and why. Just hauling your production DB into a test system translates to "I have no idea what I'm doing or why and if something break...
How do I escape double quotes in attributes in an XML String in T-SQL?
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tSql escapes a double quote with another double quote. So if you wanted it to be part of your sql string literal you would do this:
declare @xml xml
set @xml = "<transaction><item value=""hi"" /></transaction...