18 examples

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Expressing Queries in DBest

This section presents various ways to express queries in DBest, including SQL representations and alternative request structures.

DBest supports multiple ways to formulate the same query, offering flexibility in operator arrangements and query execution strategies.

The examples provided focus on subqueries, a crucial component of complex SQL queries. Subqueries involve nested processing and often include correlated variables. DBest provides specialized operators to efficiently handle subqueries and capture their nuances.

The following examples illustrate different use cases:

• 18.1 - Subqueries in the WHERE clause

  • 18.1.1 - IN vs EXISTS
  • 18.1.2 - NOT IN vs NOT EXISTS
  • 18.1.3 - ANY and ALL
  • 18.1.4 - Subqueries and direct comparisons
  • 18.1.5 - Subqueries in boolean expressions

• 18.2 - Subqueries in the FROM clause

• 18.3 - Subqueries in the SELECT clause

• 18.4 - ETL example