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Primary Key Cascade Question
In an Access 2007 db, I have 5 tables, with Proj_No the Primary Key field in
the main table tblProjID. It has 7 additional fields. It will be benificial to have Proj_No in the other 4 tables as foreign key fields. My question is, when a new Proj_No is entered into the main table to create a new record, how can I get that entry (alpha-numeric) to cascade to the other 4 tables, thus creating a new record in the 4 child tables. Thank you Marsh |
#2
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Primary Key Cascade Question
On Tue, 20 Apr 2010 12:00:01 -0700, Marsh
wrote: In an Access 2007 db, I have 5 tables, with Proj_No the Primary Key field in the main table tblProjID. It has 7 additional fields. It will be benificial to have Proj_No in the other 4 tables as foreign key fields. My question is, when a new Proj_No is entered into the main table to create a new record, how can I get that entry (alpha-numeric) to cascade to the other 4 tables, thus creating a new record in the 4 child tables. Don't. It's neither necessary nor helpful to have empty "placeholder" records in your related tables. If you use a Form based on the main table, with Subforms for your related tables (using Proj_No as the Master/Child Link Field), the Proj_No will fill in when you add data to the child table. That's when you need the foreign key - when there is data to link, not before. If you're adding data in table datasheets, don't! Tables are VERY limiting and (despite Microsoft's blandishments) inappropriate for data entry or editing. Forms are much more powerful and flexible. -- John W. Vinson [MVP] |
#3
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Primary Key Cascade Question
You shouldn't be creating a record in the other 4 tables unless there is a
real need for it. The best way to keep the tables linked is to first join them in the Relationships Window with Referential Integrity enabled. Next create a form based on the tblProjID table. On this form put subforms based on the other tables. It's pretty unusual to have one table linked to 4 other tables in a hub-and-spoke configuration. What is in the other tables? -- Jerry Whittle, Microsoft Access MVP Light. Strong. Cheap. Pick two. Keith Bontrager - Bicycle Builder. "Marsh" wrote: In an Access 2007 db, I have 5 tables, with Proj_No the Primary Key field in the main table tblProjID. It has 7 additional fields. It will be benificial to have Proj_No in the other 4 tables as foreign key fields. My question is, when a new Proj_No is entered into the main table to create a new record, how can I get that entry (alpha-numeric) to cascade to the other 4 tables, thus creating a new record in the 4 child tables. Thank you Marsh |
#4
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Primary Key Cascade Question
Marsh,
Go into relationships and set up relationships between all of the tables. Set the join as one-to-many (parent-to-child), enforce referential integrity and cascading updates and deletes. Also, I like to set the join type to all records in the parent and only the matching in the children. You don't have to do this but it is a good way to view parent records without children. Also, it is best to set this up before you have entered data. If you get an error while setting it up, I can help you with that. Finally, this set up will cause cascading updates and cascading deletes. The database will provide a warning and tell you how many records are being updated or deleted. Marsh wrote: In an Access 2007 db, I have 5 tables, with Proj_No the Primary Key field in the main table tblProjID. It has 7 additional fields. It will be benificial to have Proj_No in the other 4 tables as foreign key fields. My question is, when a new Proj_No is entered into the main table to create a new record, how can I get that entry (alpha-numeric) to cascade to the other 4 tables, thus creating a new record in the 4 child tables. Thank you Marsh |
#5
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Primary Key Cascade Question
Three very informative answers, and I shall work on this today. If problems
arise, I will be back tomorrow. Thank you all "SQLGal" wrote: Marsh, Go into relationships and set up relationships between all of the tables. Set the join as one-to-many (parent-to-child), enforce referential integrity and cascading updates and deletes. Also, I like to set the join type to all records in the parent and only the matching in the children. You don't have to do this but it is a good way to view parent records without children. Also, it is best to set this up before you have entered data. If you get an error while setting it up, I can help you with that. Finally, this set up will cause cascading updates and cascading deletes. The database will provide a warning and tell you how many records are being updated or deleted. Marsh wrote: In an Access 2007 db, I have 5 tables, with Proj_No the Primary Key field in the main table tblProjID. It has 7 additional fields. It will be benificial to have Proj_No in the other 4 tables as foreign key fields. My question is, when a new Proj_No is entered into the main table to create a new record, how can I get that entry (alpha-numeric) to cascade to the other 4 tables, thus creating a new record in the 4 child tables. Thank you Marsh . |
#6
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Primary Key Cascade Question
Not meaning to be excessively picky, and with respect for your knowledge and
experience as demonstrated by your posts over the years, is it unusual to have four child tables? I have at least one database with four, and several with three, and I don't think I'm operating at an especially sophisticated level as such things go. As an example of four child tables, a training database has a main Training Session record, with related records for documents (e.g. Standard Operating Procedures), PartNumber (we process machine parts, several of which may be related closely enough that they are covered by a single training session), trainers, and attendees. That said, I am curious too about the other tables the OP mentioned :-) Jerry Whittle wrote: You shouldn't be creating a record in the other 4 tables unless there is a real need for it. The best way to keep the tables linked is to first join them in the Relationships Window with Referential Integrity enabled. Next create a form based on the tblProjID table. On this form put subforms based on the other tables. It's pretty unusual to have one table linked to 4 other tables in a hub-and-spoke configuration. What is in the other tables? In an Access 2007 db, I have 5 tables, with Proj_No the Primary Key field in the main table tblProjID. It has 7 additional fields. [quoted text clipped - 5 lines] Thank you Marsh -- Message posted via AccessMonster.com http://www.accessmonster.com/Uwe/For...arted/201004/1 |
#7
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Primary Key Cascade Question
Hi Bruce,
You are correct that there can be many valid reasons for having that many child tables. Probably because this is the New Users forum, I assumed (and we know what that can mean) the the OP might have been doing something like a table for each year or something. Thanks for keeping me honest! -- Jerry Whittle, Microsoft Access MVP Light. Strong. Cheap. Pick two. Keith Bontrager - Bicycle Builder. "BruceM via AccessMonster.com" wrote: Not meaning to be excessively picky, and with respect for your knowledge and experience as demonstrated by your posts over the years, is it unusual to have four child tables? I have at least one database with four, and several with three, and I don't think I'm operating at an especially sophisticated level as such things go. As an example of four child tables, a training database has a main Training Session record, with related records for documents (e.g. Standard Operating Procedures), PartNumber (we process machine parts, several of which may be related closely enough that they are covered by a single training session), trainers, and attendees. That said, I am curious too about the other tables the OP mentioned :-) Jerry Whittle wrote: You shouldn't be creating a record in the other 4 tables unless there is a real need for it. The best way to keep the tables linked is to first join them in the Relationships Window with Referential Integrity enabled. Next create a form based on the tblProjID table. On this form put subforms based on the other tables. It's pretty unusual to have one table linked to 4 other tables in a hub-and-spoke configuration. What is in the other tables? In an Access 2007 db, I have 5 tables, with Proj_No the Primary Key field in the main table tblProjID. It has 7 additional fields. [quoted text clipped - 5 lines] Thank you Marsh -- Message posted via AccessMonster.com http://www.accessmonster.com/Uwe/For...arted/201004/1 . |
#8
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Primary Key Cascade Question
There were overriding reasons why I needed multiple tables, related as spokes
of a wheel. I like your analogy and will "borrow it" for our next project meeting. It had to do with the who/how data entry is to be done, with a form(s) in individual front ends, differing as job description varies. It is very possible that better design could be accomplished by someone with more experience than I, and as I continue my growth with DB skills, I will improve on past designs. "Jerry Whittle" wrote: Hi Bruce, You are correct that there can be many valid reasons for having that many child tables. Probably because this is the New Users forum, I assumed (and we know what that can mean) the the OP might have been doing something like a table for each year or something. Thanks for keeping me honest! -- Jerry Whittle, Microsoft Access MVP Light. Strong. Cheap. Pick two. Keith Bontrager - Bicycle Builder. "BruceM via AccessMonster.com" wrote: Not meaning to be excessively picky, and with respect for your knowledge and experience as demonstrated by your posts over the years, is it unusual to have four child tables? I have at least one database with four, and several with three, and I don't think I'm operating at an especially sophisticated level as such things go. As an example of four child tables, a training database has a main Training Session record, with related records for documents (e.g. Standard Operating Procedures), PartNumber (we process machine parts, several of which may be related closely enough that they are covered by a single training session), trainers, and attendees. That said, I am curious too about the other tables the OP mentioned :-) Jerry Whittle wrote: You shouldn't be creating a record in the other 4 tables unless there is a real need for it. The best way to keep the tables linked is to first join them in the Relationships Window with Referential Integrity enabled. Next create a form based on the tblProjID table. On this form put subforms based on the other tables. It's pretty unusual to have one table linked to 4 other tables in a hub-and-spoke configuration. What is in the other tables? In an Access 2007 db, I have 5 tables, with Proj_No the Primary Key field in the main table tblProjID. It has 7 additional fields. [quoted text clipped - 5 lines] Thank you Marsh -- Message posted via AccessMonster.com http://www.accessmonster.com/Uwe/For...arted/201004/1 . |
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