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Home » U++ Library support » U++ SQL » How can .sch express a many-to-many relationship ? (A minimal DDL example is provided -- how should this be expressed in .sch?)
How can .sch express a many-to-many relationship ? [message #47468] Thu, 19 January 2017 23:48 Go to next message
jfranks is currently offline  jfranks
Messages: 36
Registered: September 2014
Location: Houston, Texas
Member
Fellow developers,

I've been tasked with implementing a schema using SQLite + Upp.
Sql is not my strong suit, so I used a tool that converted an ERD --> DDL.
As I discovered, UPP has it's own .sch language representation that has benefits and DDL is derived from.

However, I could not find examples of a many-to-many relationship being expressed in .sch and am somewhat over-loaded with all the tasks ahead of me.

I figured that I could just convert by hand the DDL and produce a representative .sch -- and this worked except I could not figure out the many-to-many expressions needed in .sch

The following is a minimal DDL example that I cannot figure out how to do in .sch.

Can someone give me some pointers on this?

Thank you.

-- Jeff Franks

---------- Example DDL for a many-to-many relationship ----------
--
-- multiple user accounts w/ the possibility of multiple roles
--

CREATE TABLE USER_ACCOUNT (
ID INTEGER PRIMARY KEY,
NAME varchar(255));

CREATE TABLE ROLE (
ID INTEGER PRIMARY KEY,
ASPECT integer(2),
DESCRIPTION varchar(255));

CREATE TABLE USER_ROLE (
USER_ACCOUNT_ID integer(10),
ROLE_ID integer(10),
PRIMARY KEY(USER_ACCOUNT_ID, ROLE_ID),
FOREIGN KEY(USER_ACCOUNT_ID) REFERENCES USER_ACCOUNT(ID),
FOREIGN KEY(ROLE_ID) REFERENCES ROLE(ID));
Re: How can .sch express a many-to-many relationship ? [message #47694 is a reply to message #47468] Tue, 07 March 2017 13:03 Go to previous message
mirek is currently offline  mirek
Messages: 13984
Registered: November 2005
Ultimate Member
There might be errors, doing it from the head:

TABLE_(USER_ACCOUNT)
   ISERIAL  (ID) PRIMARY_KEY
   STRING_  (NAME, 255)
END_TABLE

TABLE_(ROLE)
   ISERIAL  (ID) PRIMARY_KEY
   INT_     (ASPECT)
   STRING_  (DESCRIPTION, 255)
END_TABLE

TABLE_(USER_ROLE)
   INT_     (USER_ACCOUNT_ID) REFERENCES(USER_ACCOUNT)
   INT_     (ROLE_ID) REFERENCES(ROLE)
   DUAL_PRIMARY_KEY (USER_ACCOUNT_ID, ROLE_ID)
END_TABLE


(I suspect it is too late for you to help, but putting it here for future reference...)
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