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This chapter discusses search condition clauses and the predicates
used in them. The following sections are presented: A search condition specifies criteria for choosing rows to
select, update, delete, insert, permit in a table, or fire rules
on. Search conditions are parameters in the following statements: In the SELECT statement, search conditions are used for two purposes
as follows: In the WHERE
clause, to determine rows to retrieve for further processing. The
only expressions not valid in this clause are aggregate functions
and expressions containing LONG columns that are not in long column
functions. In the HAVING clause, to specify a test to apply
to each group of rows surviving the GROUP BY clause test(s). If
a GROUP BY clause is not used, the test is applied to all the rows
meeting the WHERE clause conditions. References in a HAVING clause to
non-grouping columns must be from within aggregate functions. Grouping columns
can be referred to by name or with an aggregate function.
In the UPDATE statement, search conditions in the WHERE clause identify
rows that qualify for updating. In the DELETE statement, search conditions in the WHERE clause identify
rows that qualify for deletion. In the INSERT statement, search conditions in the embedded SELECT statement identify rows to copy from one or more tables
or views into a table. In the DECLARE CURSOR statement, search conditions in the embedded SELECT statement identify rows and columns to be processed with
a cursor. In the CREATE VIEW statement, search conditions in the embedded SELECT statement identify rows and columns that qualify for
the view. In table CHECK constraints, the search condition identifies valid
rows that a table may contain. In rule firing conditions, search conditions identify
conditions that cause rules to fire.
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