Re: constraints in table

Dominique Bessette - Halsema asked:
>
> Hello,
>
> How do i find the constraints on a table in SQL?  my database is linux
> based, and I cant seem to find the command.  Thanks
>

From the psql prompt, \d works for me:

billing=# \d work.clients
                     Table "work.clients"
          Column          |          Type          | Modifiers
--------------------------+------------------------+-----------
 client_id                | character varying(10)  | not null
 client_name              | character varying(60)  | not null
<...>
 source_id                | integer                |
Indexes:
    "clients_pkey" PRIMARY KEY, btree (client_id)
Check constraints:
    "clients_client_host_fee_type" CHECK (client_host_fee_type = 'P'::bpchar OR client_host_fee_type = 'M'::bpchar OR client_host_fee_type = ''::bpchar)
Foreign-key constraints:
    "$1" FOREIGN KEY (client_status) REFERENCES client_status(client_status)
    "$2" FOREIGN KEY (client_brand) REFERENCES brandinginfo(branding_id)
Triggers:
    aud_client AFTER INSERT OR DELETE OR UPDATE ON "work".clients FOR EACH ROW EXECUTE PROCEDURE "work".aud_client()
    rt_client BEFORE INSERT OR DELETE OR UPDATE ON "work".clients FOR EACH ROW EXECUTE PROCEDURE work_rt.rt_client()

If you want to see the SQL that gets these results, invoke psql with -E:

bildb-01:~/wf_progs> !! -E
psql -d billing -E
Welcome to psql 8.1.6, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
       \h for help with SQL commands
       \? for help with psql commands
       \g or terminate with semicolon to execute query
       \q to quit

billing=# \d work.clients
********* QUERY **********
SELECT c.oid,
  n.nspname,
  c.relname
FROM pg_catalog.pg_class c
     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relname ~ '^clients$'
      AND n.nspname ~ '^work$'
ORDER BY 2, 3;
**************************

********* QUERY **********
SELECT relhasindex, relkind, relchecks, reltriggers, relhasrules,
relhasoids , reltablespace
FROM pg_catalog.pg_class WHERE oid = '21191'
**************************

********* QUERY **********
SELECT a.attname,
  pg_catalog.format_type(a.atttypid, a.atttypmod),
  (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid) for 128)
   FROM pg_catalog.pg_attrdef d
   WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef),
  a.attnotnull, a.attnum
FROM pg_catalog.pg_attribute a
WHERE a.attrelid = '21191' AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
**************************

********* QUERY **********
SELECT c2.relname, i.indisprimary, i.indisunique, i.indisclustered, pg_catalog.pg_get_indexdef(i.indexrelid, 0, true), c2.reltablespace
FROM pg_catalog.pg_class c, pg_catalog.pg_class c2, pg_catalog.pg_index i
WHERE c.oid = '21191' AND c.oid = i.indrelid AND i.indexrelid = c2.oid
ORDER BY i.indisprimary DESC, i.indisunique DESC, c2.relname
**************************

********* QUERY **********
SELECT r.conname, pg_catalog.pg_get_constraintdef(r.oid, true)
FROM pg_catalog.pg_constraint r
WHERE r.conrelid = '21191' AND r.contype = 'c' ORDER BY 1
**************************

********* QUERY **********
SELECT t.tgname, pg_catalog.pg_get_triggerdef(t.oid)
FROM pg_catalog.pg_trigger t
WHERE t.tgrelid = '21191' AND (not tgisconstraint  OR NOT EXISTS  (SELECT 1 FROM pg_catalog.pg_depend d    JOIN pg_catalog.pg_constraint c ON (d.refclassid = c.tableoid AND d.refobjid = c.oid)    WHERE d.classid = t.tableoid AND d.objid = t.oid AND d.deptype = 'i' AND c.contype = 'f'))   ORDER BY 1
**************************

********* QUERY **********
SELECT conname,
  pg_catalog.pg_get_constraintdef(oid, true) as condef
FROM pg_catalog.pg_constraint r
WHERE r.conrelid = '21191' AND r.contype = 'f' ORDER BY 1
**************************

********* QUERY **********
SELECT c.relname FROM pg_catalog.pg_class c, pg_catalog.pg_inherits i WHERE c.oid=i.inhparent AND i.inhrelid = '21191' ORDER BY inhseqno ASC
**************************


This SQL may differ on different versions; this is from 8.1.

HTH,

Greg Williamson
Senior DBA
GlobeXplorer LLC, a DigitalGlobe company

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