Cannot Enter Data into Form

[BillyMac]

Hope someone can help with this one - I have searched the Forum and cannot find any reference to this problem. I have a form which was originally based on a query linking 2 tables - data entry into the form worked fine. I then needed to add another field to the form from another table so I added the 3 table to my query, linked the table and then added the required field to my form and now the form will not allow me to enter or change data in any of the fields. I have checked relationships and they all seem to be OK. I have also tried creating a new query based on the original query and added the new table to that in case there was an issue with the first join, added my new table to this query and then based the form on this new query but the problem stills persists. Is there a limit to how many tables/queries a form can be linked to? Any help would be appresicated.

Cheers,

Bill

 

[gemma-the-husky]

so what was the third table you added, and what sort of link did you add

 

[BillyMac]

OK - sorry if I didn't explain in proper detail - Table 1 holds personal details, table 2 holds dates available, relationship table 1 one-to-many to table 2, Table 3 holds dates already booked, relationship table 1 one-to-many to table 3

 

[gemma-the-husky]

if yuo have a table with two one to many joins you will get a cartesian cross product table, I think that may very well be non-updateable.

I struggle to see how your table 1 can be joined to either table, but table 2 in particular.

 

[BillyMac]

Thanks for that Gemma - I never heard of a cartesian cross product table - I will look at redesigning the table and promise to learn all I can about cartesian cross product table - got to go now but will search this Forum for it on Monday.

Cheers

 

[gemma-the-husky]

its not really a cartesian cross product - you get that if you put two tables in with no joins. in that case, if you have x items in one table and y in another, you get x times y in the resultant query.

in your case your first query will give you multiple answers for each item from table1. Adding table 3 will give you multiple answers for each row derived form the first join. so you end up with potentially a very big query result.

I was just struggling to see how you could join a table of personal details, to a table of available dates, or a table of booked dates. What result are you trying to see.

 

[BillyMac]

The database is used to book students on training courses, I send out a list of dates available for particular courses, students select which dates they are available to attend (tbleDatesAvailalbe) - one student many dates. When we have enough students available on a particular day to warrant running the course then the course is confirmed and booked (tblBookedDates) - one student many dates. The result I want on my form is to see who is available when and I have achieved this with the link between table 1 and table 2 - what I wanted to see then was who had already been on courses already so that I could work out a priority for allocation - hence wanting to link table 3 also. I think it might be better if I combine the dates tables into one - I will test it out and see how it works. Thanks for your help.

Cheers,