Knowing which data types and functions to use ads flexibility to your query repertoire. Each column in a table is defined by a data type, which in turn can server as an input to a function.
In this section is an archive of article covering the best data types and functions posts we have made.
If you’re looking for a good place to start, I would start with
Seven SQL Server Data Types you Must Know to get an understanding of to main types.
One you’ve done that, read
Built-In Functions (SQL Server) to get a good introduction to the various functions you can use to perform calculations, such as setting text to upper case, or determining the month from a date.
All the examples for this lesson are based on Microsoft SQL Server Management Studio and the sample databases AdventureWorks and WideWorldImporters. You can get started using these free tools using my guide Getting Started Using SQL Server