Stairway to T-SQL DML

Stairway to T-SQL DML Level 4: The Mathematics of SQL: Part 1

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.

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Question of the Day

Multiple Escape Characters

In SQL Server 2025, I run this code (in a database with the appropriate collation):

SELECT UNISTR('%*3041%*308A%*304C%*3068 and good night', '%*') AS 'A Classic';
What is returned?

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