SQL Server supports a number of different logical operators. These operators can be used for testing Boolean conditions that return true, false and unknown in your T-SQL code. Logical operators are useful for defining constraints to limit the rows be processed when selecting or updating data. This chapter will provide an overview of the logical […]
2020-11-04 (first published: 2020-10-09)
Learn about scalar user defined functions in this next level in the Stairway.
2020-10-21 (first published: 2020-10-08)
Joining tables is a crucial concept to understanding data relationships in a relational database. When you are working with your SQL Server data, you will often need to join tables to produce the results your application requires. Having a good understanding of set theory, and the mathematical operators available and how they are used to join tables will make it easier for you to retrieve the data you need from SQL Server.
2019-05-29 (first published: 2011-11-30)
A relational database contains tables that relate to each other by key values. When querying data from these related tables you may choose to select data from a single table or many tables. If you select data from many tables, you normally join those tables together using specified join criteria. The concepts of selecting data from tables and joining tables together is all about managing and manipulating sets of data. In Level 4 of this Stairway we will explore the concepts of set theory and mathematical operators to join, merge, and return data from multiple SQL Server tables.
2019-05-22 (first published: 2011-11-16)
This stairway level will expand on the subquery topic by discussing a type of subquery known as a correlated subquery, and explores what a correlated subquery is and how it is different from a normal subquery.
2019-05-08 (first published: 2014-03-05)