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)
The PIVOT operator was added to the Transact-SQL language in SQL Server 2005. It allows you to turn your row data on its side, so it can be presented as column data. This is useful when you want take unique column values and have them displayed as column headings, where the column headings are associated with summarized values displayed below each column heading. In this article I will be exploring how to use the PIVOT operator.
2019-04-10 (first published: 2015-05-27)
The UNPIVOT operator does just the opposite of the PIVOT operator, which we looked at in the previous level. By using the PIVOT operator we can take multiple rows of data and create as single row as output. The UNPIVOT operator will take values from a single row and will create multiple rows. Microsoft introduced the UNPIVOT operator when they rolled out SQL Server 2005. In this level I will be showing you different examples of how to use the UNPIVOT operator.
2018-02-07 (first published: 2015-06-24)
When you build applications that store data in SQL Server you will most likely have to store dates and times, and you’ll call functions to do date manipulations. It is important to understand the different date and time data types, and when to use one data type over another. In this level I will be exploring the different date and time data types and discussing when each type is appropriate.
2017-09-27 (first published: 2015-11-25)
This level of the stairway details the creation of a relational database, as well as filling in some of the history of the relational database model.
2017-08-02 (first published: 2011-11-09)
When you build applications that store records in SQL Server you will most likely have to store date and time values as part of the data. To manage all the different date related tasks you might need to perform Microsoft has introduced a number of date functions. In this stairway I will be exploring those date and time functions.
2017-07-19 (first published: 2015-10-21)
In SQL Server there are 4 different ranking functions: RANK, DENSE_RANK, NTILE, and ROW_NUMBER. These ranking functions were introduced in SQL Server 2005. In this stairway level I will be reviewing each of these different ranking functions, and will show you how to use them by providing a few examples.
2017-07-14 (first published: 2015-09-02)
There times when you need to write T-SQL code that creates specific T-SQL Code and executes it. When you do this you are creating dynamic T-SQL code. When writing dynamic T-SQL you need to understand how dynamic code opens the possibilities for a SQL injection attack.
2016-07-29 (first published: 2014-07-23)
This level discusses how to use a database VIEW to simplify your Transact-SQL(T-SQL) code. By understanding how to use a VIEW you will be able to better support writing T-SQL code to meet complex business requirements. In this article I will be discussing what a database VIEW is and then providing a number of examples to help you understand how you can use a VIEW to implement different coding scenarios.
2016-07-22 (first published: 2014-03-19)