cdm_enum_fk_candidates: Find foreign key candidates in a table
Description
Which columns are good candidates as a foreign key of a table, referencing
the primary key column of another dm object's table?
Usage
cdm_enum_fk_candidates(dm, table, ref_table)
Arguments
dm
A dm object.
table
The table whose columns should be tested for foreign key candidate potential
ref_table
A table with a primary key.
Value
A table with an overview which columns of table would be suitable candidates as
foreign key columns referencing ref_table and which columns would not.
Details
cdm_enum_fk_candidates() checks first, if ref_table has a primary key set.
For each column of table a join operation is then tried, with parameter by matching
the respective column with the primary key of ref_table. This tests implicitly for
type compatibility (on most sources). Based on the result of the join, the
entry in the result column why is:
an empty entry, if the column is a candidate
the total percentage and individual numbers of missing matches between the entries of the
respective column in table table and the primary column entries in table ref_table.
the error message triggered by the error (often stating the mismatched column types)