فیلد های sql

[na3er-faraji]

با سلام . من بیشتر برنامه هامو با access تا الان نوشتم و تو sql هم مشکلی ندارم . مشکل اصلا اینه که من میخواستم ببینم فیلد های داخل sql هر کدوم چقدر میشه توش ذخیره کرد و کدوم رو باید کی استفاده کرد؟ مثلا فرق nvarchar با ntext چیه ؟ (اینو مثال زدم . کل متغیرهاشو میخام بدونم )

[whitehat]

Data Type Description
bigint
Integer (whole number) data from –2^63 (–9,223,372,036,854,775,808) through 2^63–1 (9,223,372,036,854,775,807). Storage size is 8 bytes.
integer
Integer (whole number) data from –2^31 (–2,147,483,648) through 2^31–1 (2,147,483,647).
Storage size is 4 bytes.
smallint
Integer data from –32,768 to 32,767. Storage size is 2 bytes.
tinyint
Integer data from 0 to 255. Storage size is 1 byte.
bit
Integer data with a value of either 1 or 0.
Storage size is 1 bit.
numeric (p, s)
Fixed-precision and scale-numeric data from –10^38+1 through 10^38–1. The p variable specifies precision and can vary between 1 and 38. The s variable specifies scale and can vary between 0 and p.
Storage size is 19 bytes.
money
Monetary data values from (–2^63/10000) (–922,337,203,685,477.5808) through 2^63–1 (922,337,203,685,477.5807), with accuracy to a ten-thousandth of a monetary unit. Storage size is 8 bytes.
float
Floating point number data from –1.79E +308 through 1.79E+308
Storage size is 8 bytes.
real
Floating precision number data from –3.40E+38 through 3.40E+38.
Storage size is 4 bytes.
datetime
Date and time data from January 1, 1753, to December 31, 9999, with an accuracy of one three-hundredth second, or 3.33 milliseconds. Values are rounded to increments of .000, .003, or .007 milliseconds.
Stored as two 4-byte integers. The first 4 bytes store the number of days before or after the base date, January 1, 1900. The base date is the system's reference date. Values for datetime earlier than January 1, 1753, are not permitted. The other 4 bytes store the time of day represented as the number of milliseconds after midnight. Seconds have a valid range of 0–59.
national character(n)
Synonym:nchar(n)
Fixed-length Unicode data with a maximum length of 4000 characters. Default length = 1. Storage size, in bytes, is two times the number of characters entered.
national character varying(n)
Synonym:nvarchar(n)
Variable-length Unicode data with a length of 1 to 4000 characters. Default length = 1. Storage size, in bytes, is two times the number of characters entered.
ntext
Variable-length Unicode data with a maximum length of (2^30–2)/2 (536,870,911) characters. Storage size, in bytes, is two times the number of characters entered.
Note: ntext is no longer supported in string functions.
binary(n)
Fixed-length binary data with a maximum length of 8000 bytes. Default length = 1.
Storage size is fixed, which is the length in bytes declared in the type.
varbinary(n)
Variable-length binary data with a maximum length of 8000 bytes. Default length = 1.
Storage size varies. It is the length of the value in bytes.
image
Variable-length binary data with a maximum length of 2^30–1 (1,073,741,823) bytes.
Storage is the length of the value in bytes.
uniqueidentifier
A globally unique identifier (GUID). Storage size is 16 bytes.
IDENTITY [(s, i)]
This is a property of a data column, not a distinct data type.
Only data columns of the integer data types can be used for identity columns. A table can have only one identity column. A seed and increment can be specified and the column cannot be updated.
s (seed) = starting value
i(increment) = increment value
ROWGUIDCOL
This is a property of a data column, not a distinct data type. It is a column in a table that is defined by using the uniqueidentifier data type. A table can have only one ROWGUIDCOL column.


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