diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index b6f1a40b4a0a46c293b852be5a352d1e1d43a943..7d603ef97822848a61f278ca0331aabfe6e0e3cd 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,5 +1,5 @@
@@ -7227,6 +7227,14 @@ SELECT ... WHERE CASE WHEN x <> 0 THEN y/x > 1.5 ELSE false END;
COALESCE
+
+ NVL
+
+
+
+ IFNULL
+
+
COALESCE(value , ...)
@@ -7234,9 +7242,8 @@ SELECT ... WHERE CASE WHEN x <> 0 THEN y/x > 1.5 ELSE false END;
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:
+ 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)') ...
@@ -7246,7 +7253,9 @@ SELECT COALESCE(description, short_description, '(none)') ...
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.
+ not evaluated. This SQL-standard function provides capabilities similar
+ to NVL> and IFNULL>, which are used in some other
+ database systems.
@@ -7262,16 +7271,19 @@ SELECT COALESCE(description, short_description, '(none)') ...
- 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:
+ 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.
+