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DataSet nested relationsHi, all.
I'm trying to set relations between two DataSet tables. The problem is, that the key of the parent table has more columns than the child table, something like this: ParentTable(id, name, amount) ChildTable(id, name) So I can't relate the column "amount" to any column of ChildTable. And if I don't consider this column, the program fails on "A child row has multiple parents." Any suggestions? Thanks in advance. Vad,
In my idea it is impossible what you want to do. The dataset has no invisible keys or other relation elements. Therefore if there are more Parents with the same id, name combination, than you should have to find yourself a solution in the data. Just my thought, Cor Show quote "Vad" <vg***@walla.co.il> schreef in bericht news:1148209961.593025.275240@j73g2000cwa.googlegroups.com... > Hi, all. > > I'm trying to set relations between two DataSet tables. > The problem is, that the key of the parent table has more columns > than the child table, something like this: > > ParentTable(id, name, amount) > ChildTable(id, name) > > So I can't relate the column "amount" to any column of ChildTable. > And if I don't consider this column, the program fails on "A child row > has multiple parents." > > Any suggestions? > Thanks in advance. > As it stands, you can't make it work without adding an amount column to the
child so they match - which is ill advised. What you may want to do though, is change the key in the parent table and remove amount. Add [amount] to the child table in a mannner that the aggregate of all child records will equal the actual Amount you want in the parent record. YOu can use an Aggregate such as DataTable.Compute(Sum(Amount)); to derive the Amount and then have it available in the parent. But isn't this the same thing you just told me not to do? , you may be asking. No. The difference here is that you can choose whether or not to make the computed column part of the parent table, and even if you do, you're removing it from the Key so the tables won't be constrained by it. Aggregates work pretty elegantly so you can make the new parent Amount either a Calculated column (using its expression property) or you can just leave it out altogether and use Compute to just populate an integer or whatever number you're looking for. Hopefully the distinction is clear - if not, let me know. Thanks, Bill Show quote "Vad" <vg***@walla.co.il> wrote in message news:1148209961.593025.275240@j73g2000cwa.googlegroups.com... > Hi, all. > > I'm trying to set relations between two DataSet tables. > The problem is, that the key of the parent table has more columns > than the child table, something like this: > > ParentTable(id, name, amount) > ChildTable(id, name) > > So I can't relate the column "amount" to any column of ChildTable. > And if I don't consider this column, the program fails on "A child row > has multiple parents." > > Any suggestions? > Thanks in advance. > In article <1148209961.593025.275***@j73g2000cwa.googlegroups.com>,
vg***@walla.co.il says... > I'm trying to set relations between two DataSet tables. Hi Vad,> The problem is, that the key of the parent table has more columns > than the child table, something like this: > > ParentTable(id, name, amount) > ChildTable(id, name) Besides what Cor and Bill have said, you might want to try flipping the parent and child tables in the relationship. Make ChildTable the parent. Although I haven't tried this, but I would think you should be able to find the "parent" record (the ChildTable record) for each record in ParentTable. HTH Johneevo,
That was what I was thinking as well about, but it fails if the key from what is now the child row is not unique. Cor Show quote "johneevo" <johne_evo@no_spam_yahoo_nope.com> schreef in bericht news:MPG.1edb838f8326370a98968b@msnews.microsoft.com... > In article <1148209961.593025.275***@j73g2000cwa.googlegroups.com>, > vg***@walla.co.il says... >> I'm trying to set relations between two DataSet tables. >> The problem is, that the key of the parent table has more columns >> than the child table, something like this: >> >> ParentTable(id, name, amount) >> ChildTable(id, name) > > Hi Vad, > > Besides what Cor and Bill have said, you might want to try flipping the > parent and child tables in the relationship. Make ChildTable the > parent. > > Although I haven't tried this, but I would think you should be able to > find the "parent" record (the ChildTable record) for each record in > ParentTable. > > HTH In article <eqSr8rafGHA.4***@TK2MSFTNGP02.phx.gbl>,
notmyfirstn***@planet.nl says... Hi Cor, I'm not sure what key you are referring to. To help clarify how about if we change Vad's table names as below: ParentTable changes to TableB ChildTable changes to TableA TableA is now the parent and TableB is the child. Which table's key are you referring to? thanks Show quote > That was what I was thinking as well about, but it fails if the key from > what is now the child row is not unique. > > Cor > > "johneevo" <johne_evo@no_spam_yahoo_nope.com> schreef in bericht > news:MPG.1edb838f8326370a98968b@msnews.microsoft.com... > > In article <1148209961.593025.275***@j73g2000cwa.googlegroups.com>, > > vg***@walla.co.il says... > >> I'm trying to set relations between two DataSet tables. > >> The problem is, that the key of the parent table has more columns > >> than the child table, something like this: > >> > >> ParentTable(id, name, amount) > >> ChildTable(id, name) > > > > Hi Vad, > > > > Besides what Cor and Bill have said, you might want to try flipping the > > parent and child tables in the relationship. Make ChildTable the > > parent. > > > > Although I haven't tried this, but I would think you should be able to > > find the "parent" record (the ChildTable record) for each record in > > ParentTable. > > > > HTH > > > Table A if that becomes the parent it has for sure non unique keys in the
part Id Name, and the keys for a parent have to be unique. Cor Show quote "johneevo" <johne_evo@no_spam_yahoo_nope.com> schreef in bericht news:MPG.1edb9dde8fc0a9ec98968c@msnews.microsoft.com... > In article <eqSr8rafGHA.4***@TK2MSFTNGP02.phx.gbl>, > notmyfirstn***@planet.nl says... > Hi Cor, > > I'm not sure what key you are referring to. > > To help clarify how about if we change Vad's table names as below: > ParentTable changes to TableB > ChildTable changes to TableA > > TableA is now the parent and TableB is the child. Which table's key are > you referring to? > > thanks > >> That was what I was thinking as well about, but it fails if the key from >> what is now the child row is not unique. >> >> Cor >> >> "johneevo" <johne_evo@no_spam_yahoo_nope.com> schreef in bericht >> news:MPG.1edb838f8326370a98968b@msnews.microsoft.com... >> > In article <1148209961.593025.275***@j73g2000cwa.googlegroups.com>, >> > vg***@walla.co.il says... >> >> I'm trying to set relations between two DataSet tables. >> >> The problem is, that the key of the parent table has more columns >> >> than the child table, something like this: >> >> >> >> ParentTable(id, name, amount) >> >> ChildTable(id, name) >> > >> > Hi Vad, >> > >> > Besides what Cor and Bill have said, you might want to try flipping the >> > parent and child tables in the relationship. Make ChildTable the >> > parent. >> > >> > Although I haven't tried this, but I would think you should be able to >> > find the "parent" record (the ChildTable record) for each record in >> > ParentTable. >> > >> > HTH >> >> >> In article <O$OGyKbfGHA.4***@TK2MSFTNGP05.phx.gbl>,
notmyfirstn***@planet.nl says... OK, now I'm with you. I made the assumption (which I should have been explicit with) that since Vad used the term "key", that "id" and "name" are TableA's primary key. But I guess Vad could have just as easily meant that (id, name) are a foreign key. Show quote > Table A if that becomes the parent it has for sure non unique keys in the > part Id Name, and the keys for a parent have to be unique. > > Cor > > "johneevo" <johne_evo@no_spam_yahoo_nope.com> schreef in bericht > news:MPG.1edb9dde8fc0a9ec98968c@msnews.microsoft.com... > > In article <eqSr8rafGHA.4***@TK2MSFTNGP02.phx.gbl>, > > notmyfirstn***@planet.nl says... > > Hi Cor, > > > > I'm not sure what key you are referring to. > > > > To help clarify how about if we change Vad's table names as below: > > ParentTable changes to TableB > > ChildTable changes to TableA > > > > TableA is now the parent and TableB is the child. Which table's key are > > you referring to? > > > > thanks > > > >> That was what I was thinking as well about, but it fails if the key from > >> what is now the child row is not unique. > >> > >> Cor > >> > >> "johneevo" <johne_evo@no_spam_yahoo_nope.com> schreef in bericht > >> news:MPG.1edb838f8326370a98968b@msnews.microsoft.com... > >> > In article <1148209961.593025.275***@j73g2000cwa.googlegroups.com>, > >> > vg***@walla.co.il says... > >> >> I'm trying to set relations between two DataSet tables. > >> >> The problem is, that the key of the parent table has more columns > >> >> than the child table, something like this: > >> >> > >> >> ParentTable(id, name, amount) > >> >> ChildTable(id, name) > >> > > >> > Hi Vad, > >> > > >> > Besides what Cor and Bill have said, you might want to try flipping the > >> > parent and child tables in the relationship. Make ChildTable the > >> > parent. > >> > > >> > Although I haven't tried this, but I would think you should be able to > >> > find the "parent" record (the ChildTable record) for each record in > >> > ParentTable. > >> > > >> > HTH > >>  |
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