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熟悉傳統數據庫概念及 SQL
1. Create an index when? (choose two)
A.
Most queries are expected to retrieve more than 2% to 4% of the rows in the table.
B.
The table is updated frequently
C.
A column contains a large number of null values
D.
A column contains a wide range of values
2. 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.
data modeling
B.
virtual organization
C.
probability
D.
normalization
3. Which of the following is suitable to use index?
A.
Many duplicate rows
B.
Table with many modifications but few actual queries
C.
Table with few rows
D.
Columns often be used in ORDER BY clause
4. 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;
5. In most databases, data are organized and stored in:
A.
table
B.
view
C.
plain text
D.
directory
6. How to create a table?
A.
create table { id integer; name varchar(20)}
B.
class table { id: integer; name: String; }
C.
create table ( id integer primary key, name varchar(20));
D.
create table ( id integer primary key; name varchar(20));
7. Typically where is a database is stored?
A.
On a CDROM.
B.
In the CPU.
C.
On a Hard disk.
D.
In memory.
8. Each record in the products table has a product ID, a product name and a price. How to calculate the numbers of products whose prices are greater than $100?
A.
select total(*) from products if price > 100;
B.
select sum(*) from products where price > 100;
C.
select total(*) from products for price > 100;
D.
select count(*) from products wehre price > 100;
9. Which of the following is a collection of data items organized as a set of formally described tables from which data can be accessed or reassembled in many different ways, without having to reorganize the table?
A.
Venn Diagram
B.
Relational Database
C.
Array
D.
Splay Tree
10. 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;