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From Army <a...@golux.com>
Subject Re: Problems using CHAR function in DEFAULT statment of a CREATE TABLE
Date Thu, 16 Dec 2004 23:25:40 GMT
Bernd Ruehlicke wrote:
> 
> CREATE TABLE DOSENOTWORK (num int, created_by varchar(40) default user,
> create_date_string varchar(40) default char(current_date))
> 
> give an error as below - any idea why ?!??!
> 

The rules for what is acceptable as a column default in Derby say that the only valid functions
are datetime functions. 
  The logic that enforces this can be seen in the "defaultTypeIsValid" method of the file:

./java/engine/org/apache/derby/impl/sql/compile/ColumnDefinitionNode.java

The Derby Reference Manual also states this same restriction (albeit rather briefly):

----

Column Default

For the definition of a default value, a ConstantExpression is an expression that does not
refer to any table. It can 
include constants, date-time special registers, current schemas, users, and null.

----

A "date-time special register" here means a date-time function such as "date(current_date)"
in your first example. 
Since the function "char" is NOT a date-time function, it will throw an error.

I believe this restriction was put in place as part of the "DB2 compatibility" work was that
done in Cloudscape a while 
back.

Hope that answers your question,
Army

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