the questions are:
Given the tables:
TABLEA
Empid name
1 JOE
2 BOB
TABLEB
empid weeknumber paycheck
1 1 1000.00
1 2 1000.00
2 1 1000.00
TABLEB was defined as follows:
CREATE TABLE tableb (empid CHAR(3), weeknumber CHAR(3), paycheck DECIMAL(6,2),
CONSTRAINT const1 FOREIGN KEY (empid)
REFERENCES tablea (empid) ON DELETE SET NULL)
How many rows would be deleted from tableb if the following command is issued:
DELETE FROM tablea WHERE empid = '2'?
A 2 B 0 C3 D1
The answer is B ?why not A ?

How can i define some SQL statements sets the default qualifier to "user1"?
set current user to user1? Is it right?

Given the two following tables:
Points
Name Points
Wayne Gretzky 244
Jaromir Jagr 168
Bobby Orr 129

PIM
Name PIM
Mats Sundin 14
Jaromir Jagr 18
Bobby Orr 12
How can i define some statements will display the player's Names, points and PIM for all players?
if i define SQL statements like this: select points.name,points,pim from points,pim where points.name=pim.name.
but that can not display all name in these two table,how can i do?

Thanks any help would be great!

First question: Why should it be A? The referential action for the foreign key is not ON DELETE CASCADE. Thus, DB2 must not even attempt to delete the data in the child table. (C and D are out-of question anyway.)

You may want to read up on the concepts of constraints and referential actions. There are 5 defined in the SQL standard for ON UPDATE and ON DELETE (not all of which are fully implemented in DB2):

• RESTRICT - prevent update/delete if there are dependent rows
• NO ACTION - just do the update/delete, but the statement fails if there are dangling references after the data modification (the difference to RESTRICT is that triggers or whatever could adjust the references during statement execution)
• SET NULL - set value(s) in referencing column(s) to NULL, leaving orphans
• SET DEFAULT - set value(s) in referencing column(s) to the default value of each column; same as SET NULL if the default happens to be NULL
• CASCADE - delete/update the dependent records

Second question: The statement you quote is syntactically incorrect. The "TO" keyword cannot be used there. Besides, the CURRENT_USER special register cannot be updated: http://publib.boulder.ibm.com/infoce...c/r0008404.htm

http://publib.boulder.ibm.com/infoce...c/r0011138.htm
http://publib.boulder.ibm.com/infoce...c/r0001016.htm

Third question: have a look at outer joins.

p.s: I highly recommend that you take some SQL classes before you attempt the certification. All your questions are about standard SQL stuff and every serious database course covers that. That would help you tremendously because you would only have to learn a few DB2-specific things additionally - the SQL part is mostly common across database systems from different vendors.

Thank you very much!