Hello,

I have designed two tables, one for the main information of
maintenance, and the other for additional information. The additional
table is used when one column in the main table has the value of 1
meaning we will send it to other company to repair it. So in the
additional table we have to record the company name, address, and
delivery package number, etc. If we can do it ourself, there is then
no need to use the additional table.

I have been thinking about this approach. Is this the right way? I
think it might cause the inconsistency of the database and difficulty
to maintain the database. But I wonder if there is any alternatives.
Any suggests? Thank you a lot.

On Jun 3, 3:38 am, iher... (AT) gmail (DOT) com wrote:
You really should give more details, but I'm going to assume some
things.
(Hopefully that other definition of assume won't bite us both! 8^)

so you have something like:
Table main_maint:
serial# PK
description
installation date
... (other attributes) ...
next repair date
out for repair flag

Table repair_outside:
serial# PK
service company name
address
estimated cost
estimated return date
....(other columns)

Since you gave such a slight purpose for that flag, I'd say you don't
need it. So how do you know a machine is out for repair? if there is a
record in the repair_outside table. (note assumes repair record
deleted once machine is back in service. If history is needed, then
copy the info to repair history tables).

HTH,
Ed

On Jun 3, 3:38 am, iher... (AT) gmail (DOT) com wrote:
You really should give more details, but I'm going to assume some
things.
(Hopefully that other definition of assume won't bite us both! 8^)

so you have something like:
Table main_maint:
serial# PK
description
installation date
... (other attributes) ...
next repair date
out for repair flag

Table repair_outside:
serial# PK
service company name
address
estimated cost
estimated return date
....(other columns)

Since you gave such a slight purpose for that flag, I'd say you don't
need it. So how do you know a machine is out for repair? if there is a
record in the repair_outside table. (note assumes repair record
deleted once machine is back in service. If history is needed, then
copy the info to repair history tables).

HTH,
Ed

On Jun 3, 3:38 am, iher... (AT) gmail (DOT) com wrote:
You really should give more details, but I'm going to assume some
things.
(Hopefully that other definition of assume won't bite us both! 8^)

so you have something like:
Table main_maint:
serial# PK
description
installation date
... (other attributes) ...
next repair date
out for repair flag

Table repair_outside:
serial# PK
service company name
address
estimated cost
estimated return date
....(other columns)

Since you gave such a slight purpose for that flag, I'd say you don't
need it. So how do you know a machine is out for repair? if there is a
record in the repair_outside table. (note assumes repair record
deleted once machine is back in service. If history is needed, then
copy the info to repair history tables).

HTH,
Ed