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熟悉傳統數據庫概念及 SQL
1. Create an index when? (choose two)
A.
A column contains a large number of null values
B.
Most queries are expected to retrieve more than 2% to 4% of the rows in the table.
C.
A column contains a wide range of values
D.
The table is updated frequently
2. Which of the following is the best description for a database?
A.
A database directly contains some records.
B.
A database directly contains some rows.
C.
A database directly contains some columns.
D.
A database directly contains some tables.
3. Which of the following may be a valid SQL statement?
A.
get students where name='paul' and age>20;
B.
select students if name='paul' && age>20;
C.
choose name, id from students if name='paul' && age>20;
D.
select * from students where name='paul' and age>20;
4. Each record in the products table has a product ID, a product name and a price. How to double the prices of all products?
A.
update products by price = 2*price;
B.
update products price = 2*price;
C.
update price = 2*price from products;
D.
update products set price = 2*price;
5. Which of the following SQL statements is the correct one to copy rows from another tables?
A.
Insert into sales(item_id,name,price)on select order_id,mane ,price from orders;
B.
Insert into sales(item_id,name,price)values (Select order_id,name,price from orders);
C.
Insert into sales(item_id,name,price)as select order_id,name,price from order;
D.
Insert into sales(item_id,name,price)select order_id,name,price from orders;
6. Typically where is a database is stored?
A.
In memory.
B.
In the CPU.
C.
On a Hard disk.
D.
On a CDROM.
7. Which of the following is a standard interactive and programming language for getting information from and updating a database?
A.
Structured Query Language (SQL)
B.
National Query Language (NQL)
C.
JAVA
D.
Dynamic Query Language (DQL)
8. In creating a database, this is the process of organizing it into tables in such a way that the results of using the database are always unambiguous.
A.
normalization
B.
virtual organization
C.
data modeling
D.
probability
9. Which of the following may be a valid SQL statement?
A.
select * from students where name='paul' and age>20;
B.
select students if name='paul' && age>20;
C.
choose name, id from students if name='paul' && age>20;
D.
get students where name='paul' and age>20;
10. In most databases, data are organized and stored in:
A.
table
B.
directory
C.
view
D.
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