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MIS 430 - Data Mining > Quiz 2 - SQL Server - Datatypes > Flashcards

Quiz 2 - SQL Server - Datatypes Flashcards

1
Q

exact numerics

A
  • When data store is known precisely and no approximation is needed/allowed
  • For example all integer values. Even values with decimals such as 10.23 or 1.23456
  • These data types are useful for all integer values as well as values with decimals where exactness is useful.
  • For example: data tracking money – the number of decimal places need tracking is small, but require exactness.
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2
Q

approximate numerics

A
  • The numbers stored are made up of two parts: the mantissa and the exponent.
  • The algorithm used to produce these two parts from a number is not precise.
  • As a result, what is inserted would not be exactly what is stored and retrieved.
  • These data types are useful for scientific, statistical and engineering purposes.
  • These applications require much higher level of precision (number of digits stored) but are fine with the minor approximations in the storage.
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3
Q

date and time

A

For storing both data as well as time

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4
Q

character strings

A
  • Series of character data made up of letters, digits and symbols.
  • Each character is stored using 1-byte of space (ANSI character set which is 256 characters).
  • Maximum length allowed is 8000 characters (8000 bytes), because more than that cannot be stored in single page.
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5
Q

unicode character strings

A

• Similar to character strings, but using a broader character set (Unicode Character Set).
• Each character is stored using 2-byte of space.
• Note: Unicode character set can potentially represent a maximum of 65,536 characters.
Maximum length allowed is 4000 characters (8000 bytes).

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6
Q

binary strings

A

• for storing binary data (1s and 0s)

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7
Q

SQL: BIGINT

A
  • storage: 8 bytes

* values allowed: -2^63 to 2^63-1 (-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807)

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8
Q

SQL: INT

A
  • storage: 4 bytes

* values allowed: -2^31 to 2^31-1 (-2,147,483,648 to 2,147,483,647)

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9
Q

SQL: SMALLINT

A
  • storage: 2 bytes

* values allowed: -2^15 to 2^15-1 (-32,768 to 32,767)

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10
Q

SQL: TINYINT

A
  • storage 1 byte
  • values allowed: 0 to 2^8-1 (0 to 255)
  • note: does not allow storing negative values
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11
Q

SQL: DECIMAL(p,s)

A
  • fixed precision and scale numeric datatype
  • When maximum precision is used, valid values are from - 10^38 +1 through 10^38 - 1.
  • p (precision) is the maximum total number of decimal digits that can be stored, including both to the left and to the right of the decimal point
  • precision must be a value from 1-38
  • default precision is 18
  • s (scale) is the maximum number of decimal digits that can be stored to the right of the decimal point
  • Scale must be a value from 0-p.
  • Scale can be specified only if precision is specified.
  • default scale is 0; therefore, 0 <= p.
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12
Q

SQL: NUMERIC

A

same as DECIMAL

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13
Q

SQL: MONEY

A
  • storage: 8 bytes
  • values allowed: -922,337,203,685,477.5808 to 922,337,203,685,477.5807
  • note: stored values are accurate to a ten-thousandth of the monetary unit
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14
Q

SQL: SMALLMONEY

A
  • storage: 4 bytes
  • values allowed: - 214,748.3648 to 214,748.3647
  • note: stored values are accurate to a ten-thousandth of the monetary unit
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15
Q

SQL: BIT

A

• integer data type that can take a value of 1, 0, or NULL

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16
Q

SQL: FLOAT

A
  • approximate numeric

* values allowed: - 1.79E+308 to -2.23E-308, 0 and 2.23E-308 to 1.79E+308

17
Q

SQL: REAL

A
  • approximate numeric

* values allowed: - 3.40E + 38 to -1.18E - 38, 0 and 1.18E - 38 to 3.40E + 38

18
Q

SQL: DATETIME

A
  • storage: 4 bytes
  • values allowed: January 1, 1753, through December 31, 9999
  • accuracy of 3.33 milliseconds
19
Q

SQL: SMALLDATETIME

A
  • storage: 2 bytes
  • values allowed: January 1, 1900, through June 6, 2079
  • accuracy of 1 minute
20
Q

SQL: CHAR(n)

A
  • fixed-length, non-Unicode character data with a length of n bytes
  • n must be a value from 1 through 8,000
  • storage size is n bytes (1 byte/character).
  • default n=1
  • padding stored at the end
  • fixed-length is much faster to retrieve
21
Q

SQL: VARCHAR(n|max)

A
  • variable-length, non-Unicode character data
  • n can be a value from 1 through 8,000
  • for greater than 8000, the size is denoted using max which indicates that the maximum storage size is 2^31-1 bytes
  • note: TEXT is recommended instead of VARCHAR(MAX)
  • data entered can be 0 characters in length
22
Q

SQL: TEXT

A
  • variable-length non-Unicode data in the code page of the server and with a maximum length of 2^31-1 (2,147,483,647) characters
  • when the server code page uses double-byte characters, the storage is still 2,147,483,647 bytes.
23
Q

SQL: NCHAR(n)

A
  • Unicode version of CHAR
  • padding stored at the end
  • fixed-length is much faster to retrieve
24
Q

SQL: NVARCHAR(n|MAX)

A
  • Unicode version of VARCHAR

* n can range from 1 through 4000.

25
Q

SQL: NTEXT

A
  • Unicode version of TEXT
  • variable-length with a maximum length of 2^30 - 1 (1,073,741,823) characters
  • storage size, in bytes, is 2X the number of characters entered
26
Q

SQL: BINARY(n)

A
  • fixed-length binary data with a length of n bytes
  • n is a value from 1 through 8,000
  • storage size is n bytes
27
Q

SQL: VARBINARY(n|MAX)

A
  • variable-length binary data
  • n can be a value from 1 through 8,000
  • max indicates that the maximum storage size is 2^31-1 bytes
  • storage size is the actual length of the data entered + 2 bytes
  • data entered can be 0 bytes in length
28
Q

SQL: IMAGE

A
  • variable-length binary data from 0 through 2^31-1 (2,147,483,647) bytes.
  • equivalent to VARBINARY(max)
29
Q

SQL: TIMESTAMP

A
  • a data type that exposes automatically generated, unique binary numbers within a database
  • generally used as a mechanism for version-stamping table rows
  • storage size is 8 bytes
  • an incrementing number and does not preserve a date or a time
30
Q

SQL: UNIQUEIDENTIFIER

A
  • 16-byte code to uniquely identify a row
  • generated either randomly, or by supplying a string in which each character is a hexadecimal digit (0 to 9, or a through f)
31
Q

SQL: TABLE

A
  • special data type that can be used to store a result set for processing at a later time
  • primarily used for temporary storage of a set of rows returned as the result set of a table-valued function
  • note: TABLE is not used to define data type of a column, but for purpose described above.
32
Q

SQL: XML

A

• other datatype

33
Q

SQL: CURSOR

A

• other datatype

34
Q

SQL: SQL_VARIANT

A

• other datatype

35
Q

if there is no math, use a character datatype

A

GROUP BY works much more efficiently with a character string datatype

MIS 430 - Data Mining (5 decks)

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