Microsoft SQL Server/Variables

Declaration and affectation

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


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


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:


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



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


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

Personalized types

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

Type determination

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

FROM table1


  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.


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