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Null vs. False vs. 0 in PHP
...or a data value that doesn't exist in the database or is unknown. See dev.mysql.com/doc/refman/5.0/en/working-with-null.html or en.wikipedia.org/wiki/Null_%28SQL%29.
– Eli
Dec 5 '12 at 3:39
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Does a foreign key automatically create an index?
... I'm just about positive that PostgreSQL creates an index. I'm pretty sure MySQL does. Making the index makes a ton of sense, but IT'T NOT REQUIRED. After all, why reference something if every time the DB goes to look it up it has to do a tablescan?
– MBCook
Ma...
Getting the PublicKeyToken of .Net assemblies
...Pravat> ([system.reflection.assembly]::loadfile("C:\Program Files (x86)\MySQL\Connector NET 6.6.5\Assemblies\v4.0\MySql.Data.dll")).FullName
like
PS C:\Users\Pravat> ([system.reflection.assembly]::loadfile("dll full path")).FullName
and will appear like
MySql.Data, Version=6.6.5.0, Cu...
SQL - using alias in Group By
...OUP BY is executed before the SELECT clause.
There are exceptions though: MySQL and Postgres seem to have additional smartness that allows it.
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Cleanest way to build an SQL string in Java
...d MERGE. You can create SQL like this:
String sql1 = DSL.using(SQLDialect.MYSQL)
.select(A, B, C)
.from(MY_TABLE)
.where(A.equal(5))
.and(B.greaterThan(8))
.getSQL();
String sql2 = DSL.using(SQLDialect.MYSQL)
...
What's the longest possible worldwide phone number I should consider in SQL varchar(length) for phon
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I know that should be the case, but it's not always. In MySQL (for example) the full length is used for sorting. It's best to apply at least some minimal effort.
– Morgan Tocker
Jul 20 '10 at 18:23
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How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
... very 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.
...
App Inventor 2 低功耗蓝牙 BlueToothLE 拓展 · App Inventor 2 中文网
... Disconnect 或 DisconnectWithAddress 引起的，或者在设备移开或重置以致发生连接丢失后引起的。
FloatsReceived – 当从连接的蓝牙设备接收到一个或多个 IEEE 754 浮点值时，将触发该事件。根据上次调用 ReadFloats 或 RegisterForFlo...
互联网健身的火爆：技术驱动是内因 资本只是点缀 - 资讯 - 清泛网 - 专注C/...
...网健身的创业者们来讲是亟待解决的问题。无论创业者们如何解决这些问题，“业余是细流，专业是大坝”这个基本的原则才是保证整个产品科学发展的关键因素。
改变四：比赛还是要打的，关键是怎么打
对于很多日常的健...
INNER JOIN ON vs WHERE clause
....
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...