고정된 길이 문자열 (알파벳, 숫자, 특수문자 포함). Thesizeparameter specifies the column length in characters - 기본값 1, 0~255 까지 입력 값
VARCHAR(size)
A VARIABLE length string (can contain letters, numbers, and special characters). Thesizeparameter specifies the maximum column length in characters - can be from 0 to 65535
BINARY(size)
Equal to CHAR(), but stores binary byte strings. Thesizeparameter specifies the column length in bytes. Default is 1
VARBINARY(size)
Equal to VARCHAR(), but stores binary byte strings. Thesizeparameter specifies the maximum column length in bytes.
TINYBLOB
For BLOBs (Binary Large OBjects). Max length: 255 bytes
TINYTEXT
Holds a string with a maximum length of 255 characters
TEXT(size)
Holds a string with a maximum length of 65,535 bytes
BLOB(size)
For BLOBs (Binary Large OBjects). Holds up to 65,535 bytes of data
MEDIUMTEXT
Holds a string with a maximum length of 16,777,215 characters
MEDIUMBLOB
For BLOBs (Binary Large OBjects). Holds up to 16,777,215 bytes of data
LONGTEXT
Holds a string with a maximum length of 4,294,967,295 characters
LONGBLOB
For BLOBs (Binary Large OBjects). Holds up to 4,294,967,295 bytes of data
ENUM(val1, val2, val3, ...)
A string object that can have only one value, chosen from a list of possible values. You can list up to 65535 values in an ENUM list. If a value is inserted that is not in the list, a blank value will be inserted. The values are sorted in the order you enter them
SET(val1, val2, val3, ...)
A string object that can have 0 or more values, chosen from a list of possible values. You can list up to 64 values in a SET list
Numeric Data Types (수치 데이터 타입)
Data typeDescription
BIT(size)
A bit-value type. The number of bits per value is specified insize. Thesizeparameter can hold a value from 1 to 64. The default value forsizeis 1.
TINYINT(size)
A very small integer. Signed range is from -128 to 127. Unsigned range is from 0 to 255. Thesizeparameter specifies the maximum display width (which is 255)
BOOL
Zero is considered as false, nonzero values are considered as true.
BOOLEAN
Equal to BOOL
SMALLINT(size)
A small integer. Signed range is from -32768 to 32767. Unsigned range is from 0 to 65535. Thesizeparameter specifies the maximum display width (which is 255)
MEDIUMINT(size)
A medium integer. Signed range is from -8388608 to 8388607. Unsigned range is from 0 to 16777215. Thesizeparameter specifies the maximum display width (which is 255)
INT(size)
A medium integer. Signed range is from -2147483648 to 2147483647. Unsigned range is from 0 to 4294967295. Thesizeparameter specifies the maximum display width (which is 255)
INTEGER(size)
Equal to INT(size)
BIGINT(size)
A large integer. Signed range is from -9223372036854775808 to 9223372036854775807. Unsigned range is from 0 to 18446744073709551615. Thesizeparameter specifies the maximum display width (which is 255)
FLOAT(size,d)
A floating point number. The total number of digits is specified insize. The number of digits after the decimal point is specified in thedparameter. This syntax is deprecated in MySQL 8.0.17, and it will be removed in future MySQL versions
FLOAT(p)
A floating point number. MySQL uses thepvalue to determine whether to use FLOAT or DOUBLE for the resulting data type. Ifpis from 0 to 24, the data type becomes FLOAT(). Ifpis from 25 to 53, the data type becomes DOUBLE()
DOUBLE(size,d)
A normal-size floating point number. The total number of digits is specified insize. The number of digits after the decimal point is specified in thedparameter
DOUBLE PRECISION(size,d)
DECIMAL(size,d)
An exact fixed-point number. The total number of digits is specified insize. The number of digits after the decimal point is specified in thedparameter. The maximum number forsizeis 65. The maximum number fordis 30. The default value forsizeis 10. The default value fordis 0.
DEC(size,d)
Equal to DECIMAL(size,d)
Note:All the numeric data types may have an extra option: UNSIGNED or ZEROFILL. If you add the UNSIGNED option, MySQL disallows negative values for the column. If you add the ZEROFILL option, MySQL automatically also adds the UNSIGNED attribute to the column.
Date and Time Data Types (날짜 시간 데이터 타입)
Data typeDescription
DATE
A date. Format: YYYY-MM-DD. The supported range is from '1000-01-01' to '9999-12-31'
DATETIME(fsp)
A date and time combination. Format: YYYY-MM-DD hh:mm:ss. The supported range is from '1000-01-01 00:00:00' to '9999-12-31 23:59:59'. Adding DEFAULT and ON UPDATE in the column definition to get automatic initialization and updating to the current date and time
TIMESTAMP(fsp)
A timestamp. TIMESTAMP values are stored as the number of seconds since the Unix epoch ('1970-01-01 00:00:00' UTC). Format: YYYY-MM-DD hh:mm:ss. The supported range is from '1970-01-01 00:00:01' UTC to '2038-01-09 03:14:07' UTC. Automatic initialization and updating to the current date and time can be specified using DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP in the column definition
TIME(fsp)
A time. Format: hh:mm:ss. The supported range is from '-838:59:59' to '838:59:59'
YEAR
A year in four-digit format. Values allowed in four-digit format: 1901 to 2155, and 0000. MySQL 8.0 does not support year in two-digit format.
============================
SQL Server Data Types
String Data Types (문자열 데이터 타입)
Data typeDescriptionMax sizeStorage
char(n)
Fixed width character string
8,000 characters
Defined width
varchar(n)
Variable width character string
8,000 characters
2 bytes + number of chars
varchar(max)
Variable width character string
1,073,741,824 characters
2 bytes + number of chars
text
Variable width character string
2GB of text data
4 bytes + number of chars
nchar
Fixed width Unicode string
4,000 characters
Defined width x 2
nvarchar
Variable width Unicode string
4,000 characters
nvarchar(max)
Variable width Unicode string
536,870,912 characters
ntext
Variable width Unicode string
2GB of text data
binary(n)
Fixed width binary string
8,000 bytes
varbinary
Variable width binary string
8,000 bytes
varbinary(max)
Variable width binary string
2GB
image
Variable width binary string
2GB
Numeric Data Types (수치 데이터 타입)
Data typeDescriptionStorage
bit
Integer that can be 0, 1, or NULL
tinyint
Allows whole numbers from 0 to 255
1 byte
smallint
Allows whole numbers between -32,768 and 32,767
2 bytes
int
Allows whole numbers between -2,147,483,648 and 2,147,483,647
4 bytes
bigint
Allows whole numbers between -9,223,372,036,854,775,808 and 9,223,372,036,854,775,807
8 bytes
decimal(p,s)
Fixed precision and scale numbers.Allows numbers from -10^38 +1 to 10^38 –1. The p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. Default is 18. The s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. Default value is 0
5-17 bytes
numeric(p,s)
Fixed precision and scale numbers.Allows numbers from -10^38 +1 to 10^38 –1. The p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. Default is 18. The s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. Default value is 0
5-17 bytes
smallmoney
Monetary data from -214,748.3648 to 214,748.3647
4 bytes
money
Monetary data from -922,337,203,685,477.5808 to 922,337,203,685,477.5807
8 bytes
float(n)
Floating precision number data from -1.79E + 308 to 1.79E + 308.The n parameter indicates whether the field should hold 4 or 8 bytes. float(24) holds a 4-byte field and float(53) holds an 8-byte field. Default value of n is 53.
4 or 8 bytes
real
Floating precision number data from -3.40E + 38 to 3.40E + 38
4 bytes
Date and Time Data Types (날짜 시간 데이터 타입)
Data typeDescriptionStorage
datetime
From January 1, 1753 to December 31, 9999 with an accuracy of 3.33 milliseconds
8 bytes
datetime2
From January 1, 0001 to December 31, 9999 with an accuracy of 100 nanoseconds
6-8 bytes
smalldatetime
From January 1, 1900 to June 6, 2079 with an accuracy of 1 minute
4 bytes
date
Store a date only. From January 1, 0001 to December 31, 9999
3 bytes
time
Store a time only to an accuracy of 100 nanoseconds
3-5 bytes
datetimeoffset
The same as datetime2 with the addition of a time zone offset
8-10 bytes
timestamp
Stores a unique number that gets updated every time a row gets created or modified. The timestamp value is based upon an internal clock and does not correspond to real time. Each table may have only one timestamp variable
Other Data Types (그 외 데이터 타입)
Data typeDescription
sql_variant
Stores up to 8,000 bytes of data of various data types, except text, ntext, and timestamp
uniqueidentifier
Stores a globally unique identifier (GUID)
xml
Stores XML formatted data. Maximum 2GB
cursor
Stores a reference to a cursor used for database operations
table
Stores a result-set for later processing
MS Access Data Types (마이크로소프트 접근 데이터 타입)
Data typeDescriptionStorage
Text
Use for text or combinations of text and numbers. 255 characters maximum
Memo
Memo is used for larger amounts of text. Stores up to 65,536 characters.Note:You cannot sort a memo field. However, they are searchable
Byte
Allows whole numbers from 0 to 255
1 byte
Integer
Allows whole numbers between -32,768 and 32,767
2 bytes
Long
Allows whole numbers between -2,147,483,648 and 2,147,483,647
4 bytes
Single
Single precision floating-point. Will handle most decimals
4 bytes
Double
Double precision floating-point. Will handle most decimals
8 bytes
Currency
Use for currency. Holds up to 15 digits of whole dollars, plus 4 decimal places.Tip:You can choose which country's currency to use
8 bytes
AutoNumber
AutoNumber fields automatically give each record its own number, usually starting at 1
4 bytes
Date/Time
Use for dates and times
8 bytes
Yes/No
A logical field can be displayed as Yes/No, True/False, or On/Off. In code, use the constants True and False (equivalent to -1 and 0).Note:Null values are not allowed in Yes/No fields
1 bit
Ole Object
Can store pictures, audio, video, or other BLOBs (Binary Large OBjects)
up to 1GB
Hyperlink
Contain links to other files, including web pages
Lookup Wizard
Let you type a list of options, which can then be chosen from a drop-down list
A DB file is a database file used on mobile devices such as Android, iOS, and Windows Phone 7 mobile phones. It is often used to store contacts andSMSinformation but may store any type of device or application data. DB files are commonly stored in an SQLite database format but may also be locked or encrypted so the user cannot see the data directly.
More Information
DB files on mobile phones generally are not meant to be opened or edited manually, since they are support files that include information for the device or for an application.
One example of a DB file issms.db, an iOS support file that stores the user's text messages (located in the/private/var/mobile/Library/SMS/directory on the device). Another example of a DB file isconsolidated.db, a database file on iOS devices that automatically tracks location information.
DB파일 이란 무엇인가?
DB파일은 데이터베이스 파일의 일종으로 안드로이드, IOS, 윈도우 폰7과 같은 장치에서 사용한다. 이 파일은 연락처, 문자메세지 정보와 같은 파일을 저장하는데 사용되지만, App 정보 같은 형태도 저장할 수 있다. DB파일은 보통 SQLite의 데이터베이스 포맷으로 저장되어 암호화로 잠겨있어 바로 열어서 확인이 불가능하다.
좀더 말하자면,
휴대폰의 DB파일은은 보통 장치나 App등의 정보가 포함되는 보조적인 파일이며, 직접열어 수정이 불가능하다. 하나의 예를 들면, 사용자의 문자메세지를 저장하는 iOS에서 지원하는 sms.db파일이다.
또다른 예는, 위치정보를 자동으로 추적해주는 iOS의 데이터베이스 파일 consolidated.db 파일이다.
아래프로그램으로 열 수 있음
반응형
< 일반 데이터베이스 파일으로 사용 >
What is a DB file?
A DB file is a genericdatabasefile that stores data in a structured format, typically with an arrangement of tables, table fields, field data types, and field values. It can be created by various database programs and exported into different formats, such as.CSVfiles. DB files may also be imported by multiple database programs and are used for gaming files as well.
DB파일 이란 무엇인가?
DB파일은 일반적으로 Table 배열, Table Field, Field data Type, Filed value로 구조화된 형식으로 저장된 데이터이다. 다양한 데이터베이스 프로그램으로 생성할 수 있으며, .CSV파일과 같은 다른 포맷으로 내보낼 수 있다. DB파일은 다양한 데이터베이스 프로그램으로부터 가져올 수 있으며, 게임파일으로도 사용된다.
아래 프로그램으로 열 수 있음.
< 윈도우의 Thumbnail Cache 파일으로 사용 >
What is a DB file?
Cacheof thumbnail images that represent larger images in a Windows folder; stores small versions of images stored in a folder for quicker browsing; typically not seen unless the "Show invisible files" option is checked within the Windows view options.
More Information
Windows Thumbnail Cache files are namedThumbs.dbby default. For more information about Windows Thumbs.db files, including how to prevent them from being created,follow these instructions.
Common DB Filenames
Thumbs.db- A hidden file created by Windows for storing thumbnails of images in a folder. It can be deleted, but Windows will remake the file.
DB파일 이란 무엇인가?
Thumbnail Image Cache란, Windows에서 큰 이미지로 저장된 파일을 작은 크기의 이미지 Cache로 저장해 빠르게 브라우징(탐색)을 시킬 수 있도록 도와준다. 보통 Windows의 보기 옵션에 "보이지 않는 파일 표시" 옵션을 끄면 보이지 않습니다.
추가적으로 말하자면,
Windows Thumbnail Cache파일은 기본으로 Thumbs.db로 저장됩니다.
공통적인 DB 파일이름
Thumbs.db - 폴더 내 이미지의 축소판이 저장된 Windows가 생성한 숨김파일. 삭제할 수 있지만 재생성된다.
