Chapter 10. Type Conversion

   Table of Contents

   10.1. Overview
   10.2. Operators
   10.3. Functions
   10.4. Value Storage
   10.5. UNION, CASE, and Related Constructs
   10.6. SELECT Output Columns

   SQL statements can, intentionally or not, require the mixing of
   different data types in the same expression. PostgreSQL has extensive
   facilities for evaluating mixed-type expressions.

   In many cases a user does not need to understand the details of the
   type conversion mechanism. However, implicit conversions done by
   PostgreSQL can affect the results of a query. When necessary, these
   results can be tailored by using explicit type conversion.

   This chapter introduces the PostgreSQL type conversion mechanisms and
   conventions. Refer to the relevant sections in Chapter 8 and Chapter 9
   for more information on specific data types and allowed functions and
   operators.