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2012年 6月 15日 (金) 19:18:04 JST
Kouhei Sutou 2012-06-15 19:18:04 +0900 (Fri, 15 Jun 2012)
New Revision: 572a6d1715ab672dade14b77148d155568a13c2b
Log:
doc: describe about assingment expression
Modified files:
doc/source/spec/query_syntax.txt
Modified: doc/source/spec/query_syntax.txt (+10 -1)
===================================================================
--- doc/source/spec/query_syntax.txt 2012-06-15 18:39:07 +0900 (46e9232)
+++ doc/source/spec/query_syntax.txt 2012-06-15 19:18:04 +0900 (1c94ad4)
@@ -536,6 +536,15 @@ disabled in ``--query`` option of :doc:`/commands/select`. You need to
use groonga as a library instead of server or command line tool for
assignment expression.
+Assignment expression in query syntax has some limitations. So you
+should use :doc:`/spec/script_syntax` instead of query syntax for
+assignment.
+
There is only one syntax for assignment expression. It's ``column:=value``.
-TODO: describe me.
+``value`` is assigend to ``column``. ``value`` is always processed as
+string in query syntax. ``value`` is casted to the type of ``column``
+automatically. It causes some limitations. For example, you cannot use
+boolean literal such as ``true`` and ``false`` for ``Bool`` type
+column. You need to use empty string for ``false`` but query syntax
+doesn't support ``column:=`` syntax.