Postgres: SQL untuk mencantumkan tabel kunci asing

Apakah ada cara menggunakan SQL untuk mendaftar semua kunci asing untuk tabel yang diberikan? Saya tahu nama tabel / skema dan saya bisa pasang itu.

Anda dapat melakukan ini melalui tabel information_schema. Sebagai contoh:

SELECT
    tc.table_schema, 
    tc.constraint_name, 
    tc.table_name, 
    kcu.column_name, 
    ccu.table_schema AS foreign_table_schema,
    ccu.table_name AS foreign_table_name,
    ccu.column_name AS foreign_column_name 
FROM 
    information_schema.table_constraints AS tc 
    JOIN information_schema.key_column_usage AS kcu
      ON tc.constraint_name = kcu.constraint_name
      AND tc.table_schema = kcu.table_schema
    JOIN information_schema.constraint_column_usage AS ccu
      ON ccu.constraint_name = tc.constraint_name
      AND ccu.table_schema = tc.table_schema
WHERE tc.constraint_type = 'FOREIGN KEY' AND tc.table_name='mytable';

psql melakukan ini, dan jika Anda memulai psql dengan:

psql -E

itu akan menunjukkan kepada Anda apa yang dieksekusi. Dalam hal menemukan kunci asing, itu adalah:

SELECT conname,
  pg_catalog.pg_get_constraintdef(r.oid, true) as condef
FROM pg_catalog.pg_constraint r
WHERE r.conrelid = '16485' AND r.contype = 'f' ORDER BY 1

Dalam hal ini, 16485 adalah angka tertinggi dari tabel yang saya lihat - Anda bisa mendapatkannya dengan hanya membuang nama tab Anda ke regclass seperti:

WHERE r.conrelid = 'mytable'::regclass

Skema-kualifikasi nama tabel jika tidak unik (atau yang pertama di Anda search_path):

WHERE r.conrelid = 'myschema.mytable'::regclass

Masalah \d+ tablenamepada prompt PostgreSQL, di samping menampilkan tipe data kolom tabel itu akan menampilkan indeks dan kunci asing.

Jawaban Ollyc baik karena tidak spesifik untuk Postgres, namun rusak ketika kunci asing merujuk lebih dari satu kolom. Query berikut berfungsi untuk jumlah kolom yang berubah-ubah tetapi sangat bergantung pada ekstensi Postgres:

select 
    att2.attname as "child_column", 
    cl.relname as "parent_table", 
    att.attname as "parent_column",
    conname
from
   (select 
        unnest(con1.conkey) as "parent", 
        unnest(con1.confkey) as "child", 
        con1.confrelid, 
        con1.conrelid,
        con1.conname
    from 
        pg_class cl
        join pg_namespace ns on cl.relnamespace = ns.oid
        join pg_constraint con1 on con1.conrelid = cl.oid
    where
        cl.relname = 'child_table'
        and ns.nspname = 'child_schema'
        and con1.contype = 'f'
   ) con
   join pg_attribute att on
       att.attrelid = con.confrelid and att.attnum = con.child
   join pg_class cl on
       cl.oid = con.confrelid
   join pg_attribute att2 on
       att2.attrelid = con.conrelid and att2.attnum = con.parent

Perpanjangan resep ollyc:

CREATE VIEW foreign_keys_view AS
SELECT
    tc.table_name, kcu.column_name,
    ccu.table_name AS foreign_table_name,
    ccu.column_name AS foreign_column_name
FROM
    information_schema.table_constraints AS tc
    JOIN information_schema.key_column_usage 
        AS kcu ON tc.constraint_name = kcu.constraint_name
    JOIN information_schema.constraint_column_usage 
        AS ccu ON ccu.constraint_name = tc.constraint_name
WHERE constraint_type = 'FOREIGN KEY';

Kemudian:

SELECT * FROM foreign_keys_view WHERE table_name='YourTableNameHere';

periksa posting ff untuk solusi Anda dan jangan lupa untuk menandai ini ketika Anda merasa ini berguna

http://errorbank.blogspot.com/2011/03/list-all-foreign-keys-references-for.html

SELECT
  o.conname AS constraint_name,
  (SELECT nspname FROM pg_namespace WHERE oid=m.relnamespace) AS source_schema,
  m.relname AS source_table,
  (SELECT a.attname FROM pg_attribute a WHERE a.attrelid = m.oid AND a.attnum = o.conkey[1] AND a.attisdropped = false) AS source_column,
  (SELECT nspname FROM pg_namespace WHERE oid=f.relnamespace) AS target_schema,
  f.relname AS target_table,
  (SELECT a.attname FROM pg_attribute a WHERE a.attrelid = f.oid AND a.attnum = o.confkey[1] AND a.attisdropped = false) AS target_column
FROM
  pg_constraint o LEFT JOIN pg_class f ON f.oid = o.confrelid LEFT JOIN pg_class m ON m.oid = o.conrelid
WHERE
  o.contype = 'f' AND o.conrelid IN (SELECT oid FROM pg_class c WHERE c.relkind = 'r');

Kueri ini berfungsi dengan benar dengan kunci komposit:

select c.constraint_name
    , x.table_schema as schema_name
    , x.table_name
    , x.column_name
    , y.table_schema as foreign_schema_name
    , y.table_name as foreign_table_name
    , y.column_name as foreign_column_name
from information_schema.referential_constraints c
join information_schema.key_column_usage x
    on x.constraint_name = c.constraint_name
join information_schema.key_column_usage y
    on y.ordinal_position = x.position_in_unique_constraint
    and y.constraint_name = c.unique_constraint_name
order by c.constraint_name, x.ordinal_position

Saya pikir apa yang Anda cari dan sangat dekat dengan apa yang ditulis @ollyc adalah ini:

SELECT
tc.constraint_name, tc.table_name, kcu.column_name, 
ccu.table_name AS foreign_table_name,
ccu.column_name AS foreign_column_name 
FROM 
information_schema.table_constraints AS tc 
JOIN information_schema.key_column_usage AS kcu
  ON tc.constraint_name = kcu.constraint_name
JOIN information_schema.constraint_column_usage AS ccu
  ON ccu.constraint_name = tc.constraint_name
WHERE constraint_type = 'FOREIGN KEY' AND ccu.table_name='YourTableNameHere';

Ini akan mencantumkan semua tabel yang menggunakan tabel yang Anda tentukan sebagai kunci asing

singkat tapi manis jika itu bekerja untuk Anda.

select  * from information_schema.key_column_usage where constraint_catalog=current_catalog and table_name='your_table_name' and position_in_unique_constraint notnull;

Tidak ada jawaban yang ada yang memberikan saya hasil dalam bentuk yang saya inginkan. Jadi, inilah pertanyaan saya (raksasa) untuk mencari informasi tentang kunci asing.

Beberapa catatan:

• Ekspresi yang digunakan untuk menghasilkan from_colsdan to_colsbisa sangat disederhanakan pada Postgres 9.4 dan kemudian menggunakan WITH ORDINALITYdaripada peretasan fungsi-fungsi-jendela yang saya gunakan.
• Ekspresi yang sama bergantung pada perencana kueri tidak mengubah urutan hasil yang dihasilkan dari UNNEST. Saya rasa tidak akan, tetapi saya tidak memiliki kunci asing multi-kolom dalam dataset saya untuk diuji. Menambahkan 9,4 niceties menghilangkan kemungkinan ini sama sekali.
• Permintaan itu sendiri membutuhkan Postgres 9.0 atau lebih baru (8.x tidak mengizinkan ORDER BYfungsi agregat)
• Ganti STRING_AGGdengan ARRAY_AGGjika Anda menginginkan array kolom daripada string yang dipisahkan koma.

-

SELECT
    c.conname AS constraint_name,
    (SELECT n.nspname FROM pg_namespace AS n WHERE n.oid=c.connamespace) AS constraint_schema,

    tf.name AS from_table,
    (
        SELECT STRING_AGG(QUOTE_IDENT(a.attname), ', ' ORDER BY t.seq)
        FROM
            (
                SELECT
                    ROW_NUMBER() OVER (ROWS UNBOUNDED PRECEDING) AS seq,
                    attnum
                FROM
                    UNNEST(c.conkey) AS t(attnum)
            ) AS t
            INNER JOIN pg_attribute AS a ON a.attrelid=c.conrelid AND a.attnum=t.attnum
    ) AS from_cols,

    tt.name AS to_table,
    (
        SELECT STRING_AGG(QUOTE_IDENT(a.attname), ', ' ORDER BY t.seq)
        FROM
            (
                SELECT
                    ROW_NUMBER() OVER (ROWS UNBOUNDED PRECEDING) AS seq,
                    attnum
                FROM
                    UNNEST(c.confkey) AS t(attnum)
            ) AS t
            INNER JOIN pg_attribute AS a ON a.attrelid=c.confrelid AND a.attnum=t.attnum
    ) AS to_cols,

    CASE confupdtype WHEN 'r' THEN 'restrict' WHEN 'c' THEN 'cascade' WHEN 'n' THEN 'set null' WHEN 'd' THEN 'set default' WHEN 'a' THEN 'no action' ELSE NULL END AS on_update,
    CASE confdeltype WHEN 'r' THEN 'restrict' WHEN 'c' THEN 'cascade' WHEN 'n' THEN 'set null' WHEN 'd' THEN 'set default' WHEN 'a' THEN 'no action' ELSE NULL END AS on_delete,
    CASE confmatchtype::text WHEN 'f' THEN 'full' WHEN 'p' THEN 'partial' WHEN 'u' THEN 'simple' WHEN 's' THEN 'simple' ELSE NULL END AS match_type,  -- In earlier postgres docs, simple was 'u'nspecified, but current versions use 's'imple.  text cast is required.

    pg_catalog.pg_get_constraintdef(c.oid, true) as condef
FROM
    pg_catalog.pg_constraint AS c
    INNER JOIN (
        SELECT pg_class.oid, QUOTE_IDENT(pg_namespace.nspname) || '.' || QUOTE_IDENT(pg_class.relname) AS name
        FROM pg_class INNER JOIN pg_namespace ON pg_class.relnamespace=pg_namespace.oid
    ) AS tf ON tf.oid=c.conrelid
    INNER JOIN (
        SELECT pg_class.oid, QUOTE_IDENT(pg_namespace.nspname) || '.' || QUOTE_IDENT(pg_class.relname) AS name
        FROM pg_class INNER JOIN pg_namespace ON pg_class.relnamespace=pg_namespace.oid
    ) AS tt ON tt.oid=c.confrelid
WHERE c.contype = 'f' ORDER BY 1;

Satu cara lagi:

WITH foreign_keys AS (
    SELECT
      conname,
      conrelid,
      confrelid,
      unnest(conkey)  AS conkey,
      unnest(confkey) AS confkey
    FROM pg_constraint
    WHERE contype = 'f' -- AND confrelid::regclass = 'your_table'::regclass
)
-- if confrelid, conname pair shows up more than once then it is multicolumn foreign key
SELECT fk.conname as constraint_name,
       fk.confrelid::regclass as referenced_table, af.attname as pkcol,
       fk.conrelid::regclass as referencing_table, a.attname as fkcol
FROM foreign_keys fk
JOIN pg_attribute af ON af.attnum = fk.confkey AND af.attrelid = fk.confrelid
JOIN pg_attribute a ON a.attnum = conkey AND a.attrelid = fk.conrelid
ORDER BY fk.confrelid, fk.conname
;

Anda dapat menggunakan katalog sistem PostgreSQL . Mungkin Anda dapat meminta pg_constraint untuk meminta kunci asing. Anda juga dapat menggunakan Skema Informasi

Gunakan nama Kunci Utama yang menjadi acuan Kunci dan tanyakan informasi_schema:

select table_name, column_name
from information_schema.key_column_usage
where constraint_name IN (select constraint_name
  from information_schema.referential_constraints 
  where unique_constraint_name = 'TABLE_NAME_pkey')

Di sini 'TABLE_NAME_pkey' adalah nama Kunci Utama yang dirujuk oleh Kunci Asing.

Berikut ini adalah solusi oleh Andreas Joseph Krogh dari milis PostgreSQL: http://www.postgresql.org/message-id/200811072134.44750.andreak@officenet.no

SELECT source_table::regclass, source_attr.attname AS source_column,
    target_table::regclass, target_attr.attname AS target_column
FROM pg_attribute target_attr, pg_attribute source_attr,
  (SELECT source_table, target_table, source_constraints[i] source_constraints, target_constraints[i] AS target_constraints
   FROM
     (SELECT conrelid as source_table, confrelid AS target_table, conkey AS source_constraints, confkey AS target_constraints,
       generate_series(1, array_upper(conkey, 1)) AS i
      FROM pg_constraint
      WHERE contype = 'f'
     ) query1
  ) query2
WHERE target_attr.attnum = target_constraints AND target_attr.attrelid = target_table AND
      source_attr.attnum = source_constraints AND source_attr.attrelid = source_table;

Solusi ini menangani kunci asing yang merujuk beberapa kolom, dan menghindari duplikat (yang beberapa jawaban lainnya gagal lakukan). Satu-satunya hal yang saya ubah adalah nama variabel.

Berikut adalah contoh yang mengembalikan semua employeekolom yang mereferensikan permissiontabel:

SELECT source_column
FROM foreign_keys
WHERE source_table = 'employee'::regclass AND target_table = 'permission'::regclass;

Untuk memperluas jawaban Martin yang unggul di sini adalah kueri yang memungkinkan Anda memfilter berdasarkan tabel induk dan menunjukkan kepada Anda nama tabel anak dengan setiap tabel induk sehingga Anda dapat melihat semua tabel / kolom dependen berdasarkan pada batasan kunci asing di tabel induk.

select 
    con.constraint_name,
    att2.attname as "child_column", 
    cl.relname as "parent_table", 
    att.attname as "parent_column",
    con.child_table,
    con.child_schema
from
   (select 
        unnest(con1.conkey) as "parent", 
        unnest(con1.confkey) as "child", 
        con1.conname as constraint_name,
        con1.confrelid, 
        con1.conrelid,
        cl.relname as child_table,
        ns.nspname as child_schema
    from 
        pg_class cl
        join pg_namespace ns on cl.relnamespace = ns.oid
        join pg_constraint con1 on con1.conrelid = cl.oid
    where  con1.contype = 'f'
   ) con
   join pg_attribute att on
       att.attrelid = con.confrelid and att.attnum = con.child
   join pg_class cl on
       cl.oid = con.confrelid
   join pg_attribute att2 on
       att2.attrelid = con.conrelid and att2.attnum = con.parent
   where cl.relname like '%parent_table%'       

Solusi yang tepat untuk masalah ini, menggunakan information_schema, bekerja dengan tombol multi kolom, menggabungkan kolom dengan nama yang berbeda di kedua tabel dengan benar dan juga kompatibel dengan ms sqlsever:

select fks.TABLE_NAME as foreign_key_table_name
, fks.CONSTRAINT_NAME as foreign_key_constraint_name
, kcu_foreign.COLUMN_NAME as foreign_key_column_name
, rc.UNIQUE_CONSTRAINT_NAME as primary_key_constraint_name
, pks.TABLE_NAME as primary_key_table_name
, kcu_primary.COLUMN_NAME as primary_key_column_name
from INFORMATION_SCHEMA.TABLE_CONSTRAINTS fks -- foreign keys
inner join INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu_foreign -- the columns of the above keys
    on fks.TABLE_CATALOG = kcu_foreign.TABLE_CATALOG
    and fks.TABLE_SCHEMA = kcu_foreign.TABLE_SCHEMA
    and fks.TABLE_NAME = kcu_foreign.TABLE_NAME
    and fks.CONSTRAINT_NAME = kcu_foreign.CONSTRAINT_NAME
inner join INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS rc -- referenced constraints
    on rc.CONSTRAINT_CATALOG = fks.CONSTRAINT_CATALOG
    and rc.CONSTRAINT_SCHEMA = fks.CONSTRAINT_SCHEMA
    and rc.CONSTRAINT_NAME = fks.CONSTRAINT_NAME
inner join INFORMATION_SCHEMA.TABLE_CONSTRAINTS pks -- primary keys (referenced by fks)
    on rc.UNIQUE_CONSTRAINT_CATALOG = pks.CONSTRAINT_CATALOG
    and rc.UNIQUE_CONSTRAINT_SCHEMA = pks.CONSTRAINT_SCHEMA
    and rc.UNIQUE_CONSTRAINT_NAME = pks.CONSTRAINT_NAME
inner join INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu_primary
    on pks.TABLE_CATALOG = kcu_primary.TABLE_CATALOG
    and pks.TABLE_SCHEMA = kcu_primary.TABLE_SCHEMA
    and pks.TABLE_NAME = kcu_primary.TABLE_NAME
    and pks.CONSTRAINT_NAME = kcu_primary.CONSTRAINT_NAME
    and kcu_foreign.ORDINAL_POSITION = kcu_primary.ORDINAL_POSITION -- this joins the columns
where fks.TABLE_SCHEMA = 'dbo' -- replace with schema name
and fks.TABLE_NAME = 'your_table_name' -- replace with table name
and fks.CONSTRAINT_TYPE = 'FOREIGN KEY'
and pks.CONSTRAINT_TYPE = 'PRIMARY KEY'
order by fks.constraint_name, kcu_foreign.ORDINAL_POSITION

Catatan: Ada beberapa perbedaan antara implementasi potgresql dan sqlserver information_schemayang membuat jawaban teratas memberikan hasil yang berbeda pada kedua sistem - satu memperlihatkan nama kolom untuk tabel kunci asing dan lainnya untuk tabel kunci primer. Karenanya, saya memutuskan untuk menggunakan tampilan KEY_COLUMN_USAGE.

SELECT r.conname
      ,ct.table_name
      ,pg_catalog.pg_get_constraintdef(r.oid, true) as condef
  FROM pg_catalog.pg_constraint r, information_schema.constraint_table_usage ct
 WHERE r.contype = 'f' 
   AND r.conname = ct.constraint_name
 ORDER BY 1

Saya menulis solusi yang suka dan sering digunakan. Kode ini ada di http://code.google.com/p/pgutils/ . Lihat tampilan pgutils.foreign_keys.

Sayangnya, hasilnya terlalu bertele-tele untuk dimasukkan di sini. Namun, Anda dapat mencobanya di versi publik dari database di sini, seperti ini:

$ psql -h unison-db.org -U PUBLIC -d unison -c 'select * from pgutils.foreign_keys;

Ini bekerja dengan setidaknya 8,3. Saya mengantisipasi memperbaruinya, jika perlu, dalam beberapa bulan ke depan.

-Menerima

Saya membuat sedikit alat untuk query dan kemudian membandingkan skema basis data: Dump PostgreSQL db schema ke teks

Ada info tentang FK, tetapi respons ollyc memberikan rincian lebih lanjut.

Catatan: Jangan lupa urutan kolom saat membaca kolom kendala!

SELECT conname, attname
  FROM pg_catalog.pg_constraint c 
  JOIN pg_catalog.pg_attribute a ON a.attrelid = c.conrelid AND a.attnum = ANY (c.conkey)
 WHERE attrelid = 'schema.table_name'::regclass
 ORDER BY conname, array_position(c.conkey, a.attnum)

Ini adalah apa yang saya gunakan saat ini, itu akan mencantumkan tabel dan itu adalah batasan fkey [hapus tabel klausa dan akan mencantumkan semua tabel di katalog saat ini]:

SELECT

    current_schema() AS "schema",
    current_catalog AS "database",
    "pg_constraint".conrelid::regclass::text AS "primary_table_name",
    "pg_constraint".confrelid::regclass::text AS "foreign_table_name",

    (
        string_to_array(
            (
                string_to_array(
                    pg_get_constraintdef("pg_constraint".oid),
                    '('
                )
            )[2],
            ')'
        )
    )[1] AS "foreign_column_name",

    "pg_constraint".conindid::regclass::text AS "constraint_name",

    TRIM((
        string_to_array(
            pg_get_constraintdef("pg_constraint".oid),
            '('
        )
    )[1]) AS "constraint_type",

    pg_get_constraintdef("pg_constraint".oid) AS "constraint_definition"

FROM pg_constraint AS "pg_constraint"

JOIN pg_namespace AS "pg_namespace" ON "pg_namespace".oid = "pg_constraint".connamespace

WHERE
    --fkey and pkey constraints
    "pg_constraint".contype IN ( 'f', 'p' )
    AND
    "pg_namespace".nspname = current_schema()
    AND
    "pg_constraint".conrelid::regclass::text IN ('whatever_table_name')

yang tercepat untuk memverifikasi jawaban langsung berdasarkan sepenuhnya pada jawaban ini

IFS='' read -r -d '' sql_code << EOF_SQL_CODE
      SELECT
      o.oid
      , o.conname AS constraint_name
      , (SELECT nspname FROM pg_namespace WHERE oid=m.relnamespace) AS source_schema
      , m.relname AS source_table
      , (SELECT a.attname FROM pg_attribute a
      WHERE a.attrelid = m.oid AND a.attnum = o.conkey[1] AND a.attisdropped = false) AS source_column
      , (SELECT nspname FROM pg_namespace
      WHERE oid=f.relnamespace) AS target_schema
      , f.relname AS target_table
      , (SELECT a.attname FROM pg_attribute a
      WHERE a.attrelid = f.oid AND a.attnum = o.confkey[1] AND a.attisdropped = false) AS target_column
      , ROW_NUMBER () OVER (ORDER BY o.oid) as rowid
      FROM pg_constraint o
      LEFT JOIN pg_class f ON f.oid = o.confrelid
      LEFT JOIN pg_class m ON m.oid = o.conrelid
      WHERE 1=1
      AND o.contype = 'f'
      AND o.conrelid IN (SELECT oid FROM pg_class c WHERE c.relkind = 'r')
EOF_SQL_CODE

psql -d my_db -c "$sql_code"