13.1使用表别名别名除了用于列名和计算字段外，SQL还允许给表明起别名。这样做有两个主要理由：
（1）缩短SQL语句
（2）允许在单条SELECT语句中多次使用相同的表。SELECT cust_name,cust_contact
FROM Customers AS C,Orders AS O,OrderItems AS OI
WHERE C.cust_id = O.cust_id
A...
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数据库 时间：
2015-04-16 17:35:26
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207
Suppose that a website contains two tables, the Customers table and the Orders table.
Write a SQL query to find all customers who never order anything.
Table: Customers.
+----+-------+
| Id | Na...
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其他好文 时间：
2015-04-12 14:52:06
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124
How to extend vendor or customer master data with SAP enhancement spotshttp://sapuniversity.eu/how-to-extend-vendor-or-customer-master-data-with-sap-e...
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2015-04-11 22:12:24
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134
Description
The Pizazz Pizzeria prides itself in delivering pizzas to its customers as fast as possible. Unfortunately, due to cutbacks, they can afford to hire only one driver to do the deliveri...
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2015-04-01 15:32:04
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195
先从最简单的SQL入手来分析一下SQL的执行步骤，为什么了解执行步骤，其实与JOIN后的ON条件和WHERE条件容易混淆有关系。是先执行ON还是先执行WHERE，很大程度上会决定SQL的结果集正确与否。CREATETABLECustomers(CustomerIDCHAR(5)NOTNULLPRIMARYKEY,CityVARCHAR(10)NOTNULL);CR..
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数据库 时间：
2015-03-21 21:25:48
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152
A long-distance telephone company charges its customers by the following rules:Making a long-distance call costs a certain amount per minute, dependin...
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其他好文 时间：
2015-03-17 20:09:22
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135
3月起要求关闭所有App内的检查更新功能，苹果App Store将向用户自动提示更新，新提交审核版本如果保留检查更新入口审核时将被拒绝，请各产品团队重点关注。
10.6 - Apple and our customers place a high value on simple, refined, creative, well thought through interfaces.
Th...
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移动开发 时间：
2015-03-11 14:50:29
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140
March 11, 2015 at 3:08 AM
发件人 Apple
遇到问题（被拒绝原因）
苹果不让自己检测并提示用户更新了，我们给你截图了，自己看去吧。（貌似是新的审核规定，跪了。。。）
10.6 - Apple and our customers place a high value on simple, refined, creative, well thought th...
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移动开发 时间：
2015-03-11 10:50:58
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174
Suppose that a website contains two tables, theCustomerstable and theOrderstable. Write a SQL query to find all customers who never order anything.Tab...
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其他好文 时间：
2015-03-09 20:52:45
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197
??
QUESTION 1
You need to load information about new customers from the NEW_CUST table into the tables CUST and CUST_SPECIAL. If a new customer has acredit limit greater than 10,000, then the detai...
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其他好文 时间：
2015-03-09 10:59:39
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108
