WHY SQL?1.SQL is a very-high-level language, in which the programmer is able to avoid specifying a lot of data-manipulation details that wou ...
WHY
SQL?
(1)SELECT - FROM - WHERE statements
SELECT ... (desired attributes)
From ... (one or more tables)
WHERE ...( condition about tuples of the tables)
EX: Using Beers(name, manf), what beers are made by Busch?
SELECT name,FROM Beers,WHERE manf = 'Busch'
We may specify desc for descending order or asc for ascending order, for each attribute; ascending order is the default.
Example: order by customer_name desc
EX:From Sells(bar, beer, price), find the average price of Bud:
SELECT AVG(price)FROM SellsWHERE beer = ‘Bud’;
原标题:数据库知识点
关键词:数据库
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