Question

I am trying to extract some meta data from Oracle about foreign keys. I am using the “all_constraints” to find all referential constraints information and “all_cons_columns” to find the actual columns. However, I can’t get the order of my columns in the foreign key.

Below are 4 example tables all with 3 columns. 3 of the tables reference the table “tab_d”, but the order of the columns in the foreign key differs. This order is not reflected in the “all_cons_columns” view, so is there another place where this information is available?

create table tab_d (
    col_a int,
    col_b int,
    col_c int,
    constraint tab_d_pk primary key (col_a, col_b, col_c)
);

create table tab_e (
    ref_col_a int,
    ref_col_b int,
    ref_col_c int,
    constraint tab_e_fk foreign key (ref_col_b, ref_col_c, ref_col_a)
        references tab_d(col_b, col_c, col_a)
);

create table tab_f (
    ref_col_a int,
    ref_col_b int,
    ref_col_c int,
    constraint tab_f_fk foreign key (ref_col_b, ref_col_c, ref_col_a)
        references tab_d(col_c, col_a, col_b)
);

create table tab_g (
    ref_col_a int,
    ref_col_b int,
    ref_col_c int,
    constraint tab_g_fk foreign key (ref_col_c, ref_col_b, ref_col_a)
        references tab_d(col_c, col_b, col_a)
);

The information i get from “all_cons_columns” is shown below and e.g. I my table “tab_g” where I thought position show the column order ref_col_c = 1, ref_col_b = 2 and ref_col_a = 3 it shows what order the column is in the primary key.

CONSTRAINT_NAME TABLE_NAME  COLUMN_NAME  POSITION
TAB_F_FK           TAB_F       REF_COL_A    2
TAB_F_FK           TAB_F       REF_COL_B    3
TAB_F_FK           TAB_F       REF_COL_C    1
TAB_E_FK           TAB_E       REF_COL_A    1
TAB_E_FK           TAB_E       REF_COL_B    2
TAB_E_FK           TAB_E       REF_COL_C    3
TAB_G_FK           TAB_G       REF_COL_A    1
TAB_G_FK           TAB_G       REF_COL_B    2
TAB_G_FK           TAB_G       REF_COL_C    3

Answer 1

The order of the columns is reflected in the ALL_CONS_COLUMNS view – by the column called POSITION.