dm (version 0.0.5)

cdm_enum_fk_candidates: Find foreign key candidates in a table

Description

Determine which columns would be good candidates to be used as foreign keys of a table, and reference the primary key column of another dm object's table.

Usage

cdm_enum_fk_candidates(dm, table, ref_table)
enum_fk_candidates(zoomed_dm, ref_table)

Arguments

dm

A dm object.

table

The table whose columns should be tested for suitability of use as foreign keys.

ref_table

A table with a primary key.

zoomed_dm

A dm with a zoomed table.

Value

A table that lists which columns of table would be suitable candidates for foreign key columns to reference ref_table, and which columns would not be suitable.

Details

cdm_enum_fk_candidates() first checks if ref_table has a primary key set. Then, for each column of table, a join operation will be tried, with argument 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)

enum_fk_candidates() works like cdm_enum_fk_candidates() with the zoomed table as table.

See Also

Other foreign key functions: cdm_add_fk(), cdm_get_all_fks(), cdm_get_fk(), cdm_has_fk(), cdm_rm_fk()

Examples

# NOT RUN {
cdm_enum_fk_candidates(cdm_nycflights13(), flights, airports)

# }