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 Types The possible variable types are similar to the table fields oneshttps://msdn.microsoft.com/en-US/library/ms187752.aspx: Characters 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 GBhttps://msdn.microsoft.com/en-US/library/ms176089.aspx : varchar(MAX) Numbers decimal, int (tinyint, smallint, bigint), float, money, numeric, real, smallmoney. Dates 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 typehttps://msdn.microsoft.com/en-us/library/ms178550.aspx. Example: SELECT SQL_VARIANT_PROPERTY(Field1, 'BaseType') FROM table1 References