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Published in:
2015 | OriginalPaper | Chapter
3. Procedural Code
Authors : Miguel Cebollero, Jay Natarajan, Michael Coles
Published in: Pro T-SQL Programmer's Guide
Publisher: Apress
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Abstract
T-SQL has always included support for procedural programming in the form of control-of-flow statements and cursors. One thing that throws developers from other languages off their guard when migrating to SQL is the peculiar three-valued logic (3VL) we enjoy. Chapter 1 introduced you to SQL 3VL, and this chapter expands further on this topic. SQL 3VL is different from most other programming languages’ simple two-valued Boolean logic. This chapter also discusses T-SQL control-of-flow constructs, which allow you to change the normally sequential order of statement execution. Control-of-flow statements let you branch your code logic with statements like
IF…ELSE…, perform loops with statements like WHILE, and perform unconditional jumps with the GOTO statement. You’re also introduced to CASE expressions and CASE-derived functions that return values based on given comparison criteria in an expression. Finally, we finish the chapter by explaining a topic closely tied to procedural code: SQL cursors.