HP 3000 Manuals

ALLBASE/SQL Reference Manual

Chapter 8  Expressions 

This chapter discusses value specification.  The following sections are
presented:

   *   Expression
   *   Add Months Function
   *   Aggregate Functions[REV BEG]
   *   CAST Function
   *   Constant
   *   Current Functions
   *   Date/Time Functions[REV END]
   *   Long Column Functions
   *   String Functions
   *   TID Function

An expression specifies a value to be obtained in one of the following
ways:

   *   From a column of a table
   *   From a host variable in an application program
   *   From a dynamic parameter
   *   From a local variable or parameter in a procedure
   *   From a constant
   *   By adding, subtracting, multiplying, dividing, or negating values
   *   By evaluating an aggregate function
   *   By evaluating a date/time (conversion, current, or add months)
       function
   *   By evaluating a long column or string function
   *   By a combination of these methods

Expressions are used for several purposes including:

   *   To identify columns.  In the SELECT statement, expressions are
       used in the select list to identify column values to be retrieved.

       The SELECT statement is also part of the CREATE VIEW, DECLARE
       CURSOR, and INSERT statements.  The expressions in this case
       identify columns that qualify for the view, the cursor, or the
       insert operation.[REV BEG]

   *   To identify rows.  In the search condition of the following
       statements, expressions help define the set of rows to be operated
       on:  SELECT, INSERT, UPDATE, DELETE, CREATE VIEW, and DECLARE.
       Refer to the "Search Conditions" chapter for more information.

   *   To define a new column value.  In the UPDATE statement,
       expressions define a new value for a column in an existing
       row.[REV END]

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