Microsoft SQL Server/Variables

Declaration and affectationEdit

Every variable name begins with an at.

  • Integer operations:
declare @i int
set @i = 5

declare @j int
set @j = 6

print @i+@j -- displays 11
  • Character operations:
declare @k char
set @k = '5'

declare @l char
set @l = '6'

print @k+@l -- displays 56

TypesEdit

The possible variable types are similar to the table fields ones[1]:

CharactersEdit

Those beginning by "n" are in Unicode format.

char, nchar, nvarchar, ntext, text, varchar.

To save a few memory space, it's possible to set a characters number limit during the declaration:

varchar(255)

The variable of characters maximum size is 2 GB[2] :

varchar(MAX)

NumbersEdit

decimal, int (tinyint, smallint, bigint), float, money, numeric, real, smallmoney.

DatesEdit

date, datetime, datetime2, datetimeoffset, smalldatetime, time.

Personalized typesEdit

In addition to the native types, it's possible to create one's own data types with CREATE TYPE.

Type determinationEdit

The function SQL_VARIANT_PROPERTY returns a given field type[3]. Example:

SELECT SQL_VARIANT_PROPERTY(Field1, 'BaseType')
FROM table1

ReferencesEdit