Microsoft SQL Server/Variables
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Declaration and affectation[edit | edit source]
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
Types[edit | edit source]
The possible variable types are similar to the table fields ones[1]:
Characters[edit | edit source]
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)
Numbers[edit | edit source]
decimal, int (tinyint, smallint, bigint), float, money, numeric, real, smallmoney.
Dates[edit | edit source]
date, datetime, datetime2, datetimeoffset, smalldatetime, time.
Personalized types[edit | edit source]
In addition to the native types, it's possible to create one's own data types with CREATE TYPE.
Type determination[edit | edit source]
The function SQL_VARIANT_PROPERTY returns a given field type[3]. Example:
SELECT SQL_VARIANT_PROPERTY(Field1, 'BaseType')
FROM table1