thank u ,
SELECT constraint_name
FROM information_schema.table_constraints AS tc
WHERE tc.table_name = p_table_name
AND constraint_name IN (SELECT constraint_name
FROM information_schema.table_constraints AS tc
WHERE tc.table_name =
p_ref_table_name
AND tc.constraint_type =
'PRIMARY KEY');
is this correct process same as above ..
but i want check "r_constraint_name" instead of "constraint_name" in outer statement in above code..
please let me know..
thanks in advance,
ramesh
On Tue, Jul 22, 2014 at 7:52 AM, Adrian Klaver <adrian.klaver@xxxxxxxxxxx> wrote:
From psql:On 07/19/2014 12:26 PM, Ramesh T wrote:
Hi,
In oracle got constraint details using user_constraint,
But in postgres how to get the r_constraint_name,constraint_name of the
particular table...?
mainly i need r_constraint_name on table.. how to get it?please let me know
test=> CREATE TABLE parent_tbl(id serial primary key, fld_1 text);
NOTICE: CREATE TABLE will create implicit sequence "parent_tbl_id_seq" for serial column "parent_tbl.id"
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "parent_tbl_pkey" for table "parent_tbl"
CREATE TABLE
test=> CREATE TABLE child_tbl (id serial primary key, fk_fld integer references parent_tbl, fld_2 text);
NOTICE: CREATE TABLE will create implicit sequence "child_tbl_id_seq" for serial column "child_tbl.id"
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "child_tbl_pkey" for table "child_tbl"
CREATE TABLE
test=> \d parent_tbl
Table "public.parent_tbl"
Column | Type | Modifiers
--------+---------+---------------------------------------------------------
id | integer | not null default nextval('parent_tbl_id_seq'::regclass)
fld_1 | text |
Indexes:
"parent_tbl_pkey" PRIMARY KEY, btree (id)
Referenced by:
TABLE "child_tbl" CONSTRAINT "child_tbl_fk_fld_fkey" FOREIGN KEY (fk_fld) REFERENCES parent_tbl(id)
test=> \d child_tbl
Table "public.child_tbl"
Column | Type | Modifiers
--------+---------+--------------------------------------------------------
id | integer | not null default nextval('child_tbl_id_seq'::regclass)
fk_fld | integer |
fld_2 | text |
Indexes:
"child_tbl_pkey" PRIMARY KEY, btree (id)
Foreign-key constraints:
"child_tbl_fk_fld_fkey" FOREIGN KEY (fk_fld) REFERENCES parent_tbl(id)
If you want to know what query psql uses to get this information start psql with -E, this will tell you that the queries are:
To get the child key that references the parent from the parent:
test=> SELECT conname, conrelid::pg_catalog.regclass,
pg_catalog.pg_get_constraintdef(c.oid, true) as condef
FROM pg_catalog.pg_constraint c
WHERE c.confrelid = 'parent_tbl'::regclass AND c.contype = 'f' ORDER BY 1
;
conname | conrelid | condef
-----------------------+-----------+------------------------------------------------
child_tbl_fk_fld_fkey | child_tbl | FOREIGN KEY (fk_fld) REFERENCES parent_tbl(id)
To get the information from the child table:
test=> SELECT conname,
pg_catalog.pg_get_constraintdef(r.oid, true) as condef
FROM pg_catalog.pg_constraint r
WHERE r.conrelid = 'child_tbl'::regclass AND r.contype = 'f' ORDER BY 1
;
conname | condef
-----------------------+------------------------------------------------
child_tbl_fk_fld_fkey | FOREIGN KEY (fk_fld) REFERENCES parent_tbl(id)
I used the regclass cast to convert the table names to the appropriate ids the query expects. In the psql output you will see the numbers.
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
