Index: doc/src/sgml/func.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/func.sgml,v
retrieving revision 1.295
diff -c -c -r1.295 func.sgml
*** doc/src/sgml/func.sgml 19 Nov 2005 19:44:54 -0000 1.295
--- doc/src/sgml/func.sgml 28 Nov 2005 23:17:42 -0000
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*** 7227,7232 ****
--- 7227,7240 ----
COALESCE
+
+ NVL
+
+
+
+ IFNULL
+
+
COALESCE(value , ...)
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*** 7234,7242 ****
The COALESCE function returns the first of its
arguments that is not null. Null is returned only if all arguments
! are null. This is often useful to substitute a
! default value for null values when data is retrieved for display,
! for example:
SELECT COALESCE(description, short_description, '(none)') ...
--- 7242,7249 ----
The COALESCE function returns the first of its
arguments that is not null. Null is returned only if all arguments
! are null. It is often used to substitute a default value for
! null values when data is retrieved for display, for example:
SELECT COALESCE(description, short_description, '(none)') ...
***************
*** 7246,7252 ****
Like a CASE expression, COALESCE will
not evaluate arguments that are not needed to determine the result;
that is, arguments to the right of the first non-null argument are
! not evaluated.
--- 7253,7261 ----
Like a CASE expression, COALESCE will
not evaluate arguments that are not needed to determine the result;
that is, arguments to the right of the first non-null argument are
! not evaluated. This SQL-standard function provides capabilities similar
! to NVL> and IFNULL>, which are used in some other
! database systems.
***************
*** 7262,7277 ****
! The NULLIF function returns a null value if and only
! if value1 and
! value2 are equal. Otherwise it returns
! value1. This can be used to perform the
! inverse operation of the COALESCE example
! given above:
SELECT NULLIF(value, '(none)') ...
--- 7271,7289 ----
! The NULLIF function returns a null value if
! value1 and value2
! are equal; otherwise it returns value1.
! This can be used to perform the inverse operation of the
! COALESCE example given above:
SELECT NULLIF(value, '(none)') ...
+
+ If value1 is (none)>, return a null,
+ otherwise return value1.
+