SQL2

Question 0

SQL built-in data type categories?

Answer 0

Exact numbers
Approximate numbers
Date and time
Character strings
Unicode character strings
Binary strings
Other data types
CLR data types:(common language runtime)
Spatial data types

Question 1

Data type?

Answer 1

Is an attribute that specifies the type of data an object can hold. As well as how many bytes each data type takes up.

Question 2

Most commonly used data type?

Answer 2

Money
Datetime
Integer (int) : numeric data type
varchar or nvarchar (international)
Boolean: bit data type (T or F)
Float: numeric data type  ( 4-byte-7 digits / 8-byte-15 digits)

Question 3

Exact number?

Answer 3

Bit 1b
Tinyint 1b
Smallint 2b
Int 4b
Bigint 8b
Numberic varies
Decimal varies
Smallmoney 4b
Money 8 b

Question 4

Character strings?

Answer 4

Char: fixed length
Varchar: variable length

A regular character uses one byte of storage for each character.

Syntax ‘ ‘ ( single quotes)

Question 5

Unicode character strings?

Answer 5

Nchar: fixed length
Nvarchar: variable length

(2 x storages)

Question 6

Character strings?

Answer 6

Char: fixed length
Varchar: variable length

A regular character uses one byte of storage for each character.

Syntax ‘ ‘ ( single quotes)

Question 7

Binary strings?

Answer 7

Binary: fixed length
Varbinary: variable length

Ex: image

Question 8

What determined when two expressions have different data type?

Answer 8

1. Lower precedence converted to higher precedence
2. SQL Server predefined collation precedence
3. The result depend on the precision,scale,length of the input expression

Question 9

Scales(s)?

Answer 9

Reflects the maximum number of decimal digits that can be stored to the right of the decimal point.

Ex: decimal [(p[,s])]

Question 10

Precision (p)?

Answer 10

Is the maximum total number of decimal digits that can be stored,both to the left and to the right of the decimal point. This value must be at least 1 and at most 38. The default precision number is 18.

Ex: decimal [(p[,s])]

Question 11

Implicit conversions?

Answer 11

Data type conversion are done automatically.

Question 12

Two common naming convention ?

Answer 12

PacalCase
camelCase

No space or use _ as word separators

Question 13

Explicit conversion?

Answer 13

Data type conversions require you to use the functions Cast or Convert specifically.

Cast and Convert functions

Question 14

A view?

Answer 14

Is simply a virtual table consisting of different columns from one or more tables.

Question 15

Two major reasons why provide database view?

Answer 15

1. Views allow you to limit the type of data users can access.
2. Views reduce complexity for end users so they don’t have to learn how to write complex SQL queries.

-Indexing to the schema can actually increase the overhead of database

Question 16

SQL injections?

Answer 16

is an attack in which malicious code is inserted into strings that are later passed on to instances of SQL Server waiting for parsing and execution. (metadata)