SQL/MP Query Guide

Contents

HP NonStop SQL/MP Query Guide—524488-003

1. Retrieving Data: How to Write

Queries (continued)

1. Retrieving Data: How to Write Queries (continued)

Defining Predicates 1-30

Comparison Predicate 1-31

BETWEEN Predicate 1-32

LIKE Predicate 1-33

Predicates Connected by OR Operators 1-35

IN Predicate 1-36

EXISTS Predicate 1-37

Quantified Predicates 1-38

IS NULL Predicate 1-39

Multivalued Comparison Predicate 1-40

Using Multivalued Comparison Predicates in Context-Free Servers 1-41

Aggregate Functions in Predicates 1-41

Using CASE Expressions 1-43

Decoding Values 1-43

Evaluating Multiple Conditions 1-44

Computing Aggregates Based on Specific Conditions 1-45

Finding the Highest Value in a Row 1-47

Converting Long, Narrow Tables Into Short, Wide Ones 1-49

Ignoring the Largest and Smallest Values in a Set 1-51

Combining Data From More Than One Table 1-51

Types of Join Queries 1-53

Restrictions on Join Queries 1-59

Using Views With Joins 1-59

The ON Clause and the WHERE Clause in Join Queries 1-59

Using the UNION Operator 1-61

ORDER BY Clause With UNION Operator 1-63

GROUP BY and HAVING Clauses With UNION Operator 1-64

Using Collations With the UNION Operator 1-64

Developing Interactive Multistep Queries 1-65

Multilevel Group Aggregates 1-65

Computing Row Value as a Percent of All Row Values 1-66

2. The Optimizer

SQL Components and the Optimizer 2-1

SQL Executor 2-3

File System 2-3

Disk Processes 2-3

How the Optimizer Chooses an Execution Plan 2-3