hi, Robert I think you can do this: ---------------------- Table One: base_t
Access_ID primary key column_1 column_2 .... column_last ----------------------- Table extra_t ID Access_ID // from base_t , maybe releative to type B EXTREcol_1 (** one extra column) EXTREcol_2 (** another extra column) 2010/1/4 Robert lzw <[email protected]> > Hi there, > > It may not be relevant to this mailing list, but I post it here in > case somebody knows the answer to help me as a newbie of database > designing for the following simple question. Thanks in advance. > > I have about 10,000 data samples parsed from web pages. These data are > of two types, types A and B, almost 5,000 for each type, to be > populated in a single MySQL database (I hope this is a correct > approach), but have a question about the table in the database which I > should create: > > All 10,000 data samples have a unique access number, so it should be > used as the primary key in the table. Let me say in the table there > going to be the following columns: > (in Table A) > Access_ID primary key > column_1 > column_2 > .... > column_last > > However, these are true only for one of the 2 type, type A, half > amount of data (almost 5,000 data samples). For the remaining type, > type B data, the table should look like this: > (in Table B) > Access_ID [identical to those Table A] > column_1 > column_2 > .... > column_last [identical to those Table A] > EXTREcol_1 (** one extra column) > EXTREcol_2 (** another extra column) > > In a single database, if I am to use Table B, there going to be about > 5,000 data samples that would be filled with "null" on these two extra > columns, obviously violating the principle of database design. So my > question is: how should I create the table in the single MySQL > database? > > Thanks a lot in advance, > Robert > > > ------------------------------------------------------------------------------ > This SF.Net email is sponsored by the Verizon Developer Community > Take advantage of Verizon's best-in-class app development support > A streamlined, 14 day to market process makes app distribution fast and > easy > Join now and get one step closer to millions of Verizon customers > http://p.sf.net/sfu/verizon-dev2dev > _______________________________________________ > witty-interest mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/witty-interest >
------------------------------------------------------------------------------ This SF.Net email is sponsored by the Verizon Developer Community Take advantage of Verizon's best-in-class app development support A streamlined, 14 day to market process makes app distribution fast and easy Join now and get one step closer to millions of Verizon customers http://p.sf.net/sfu/verizon-dev2dev
_______________________________________________ witty-interest mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/witty-interest
