Saya memiliki database besar yang perlu saya ekstrak semua kunci utama dan kunci asing dari setiap tabel.
Saya punya pgAdmin III.
Apakah ada cara untuk melakukan ini secara otomatis dan tidak membahas setiap tabel secara manual?
Saya memiliki database besar yang perlu saya ekstrak semua kunci utama dan kunci asing dari setiap tabel.
Saya punya pgAdmin III.
Apakah ada cara untuk melakukan ini secara otomatis dan tidak membahas setiap tabel secara manual?
Jawaban:
Anda dapat menggunakan fungsi pg_get_constraintdef(constraint_oid)
dalam kueri seperti berikut:
SELECT conrelid::regclass AS table_from
, conname
, pg_get_constraintdef(oid)
FROM pg_constraint
WHERE contype IN ('f', 'p ')
AND connamespace = 'public'::regnamespace -- your schema here
ORDER BY conrelid::regclass::text, contype DESC;
Hasil:
table_from | conname | pg_get_constraintdef
------------+------------+----------------------
tbl | tbl_pkey | PRIMARY KEY (tbl_id)
tbl | tbl_col_fk | FOREIGN KEY (col) REFERENCES tbl2(col) ON UPDATE CASCADE
...
Mengembalikan semua kunci utama dan asing untuk semua tabel dalam skema yang diberikan, diperintahkan oleh tablename, PKs terlebih dahulu.
Manual tentang jenis objek identifier ( regclass
, regnamespace
, ...).
Berdasarkan solusi Erwin:
SELECT conrelid::regclass AS "FK_Table"
,CASE WHEN pg_get_constraintdef(c.oid) LIKE 'FOREIGN KEY %' THEN substring(pg_get_constraintdef(c.oid), 14, position(')' in pg_get_constraintdef(c.oid))-14) END AS "FK_Column"
,CASE WHEN pg_get_constraintdef(c.oid) LIKE 'FOREIGN KEY %' THEN substring(pg_get_constraintdef(c.oid), position(' REFERENCES ' in pg_get_constraintdef(c.oid))+12, position('(' in substring(pg_get_constraintdef(c.oid), 14))-position(' REFERENCES ' in pg_get_constraintdef(c.oid))+1) END AS "PK_Table"
,CASE WHEN pg_get_constraintdef(c.oid) LIKE 'FOREIGN KEY %' THEN substring(pg_get_constraintdef(c.oid), position('(' in substring(pg_get_constraintdef(c.oid), 14))+14, position(')' in substring(pg_get_constraintdef(c.oid), position('(' in substring(pg_get_constraintdef(c.oid), 14))+14))-1) END AS "PK_Column"
FROM pg_constraint c
JOIN pg_namespace n ON n.oid = c.connamespace
WHERE contype IN ('f', 'p ')
AND pg_get_constraintdef(c.oid) LIKE 'FOREIGN KEY %'
ORDER BY pg_get_constraintdef(c.oid), conrelid::regclass::text, contype DESC;
Akan mengembalikan tabel formulir:
| FK_Table | FK_Column | PK_Table | PK_Column |
Tidak perlu menguraikan pg_get_constraintdef()
, cukup gunakan kolom pg_constraint
tabel untuk mendapatkan detail lainnya ( dokumen ).
Di sini constraint_type
bisa:
Berdasarkan jawaban Erwin :
SELECT c.conname AS constraint_name,
c.contype AS constraint_type,
sch.nspname AS "schema",
tbl.relname AS "table",
ARRAY_AGG(col.attname ORDER BY u.attposition) AS columns,
pg_get_constraintdef(c.oid) AS definition
FROM pg_constraint c
JOIN LATERAL UNNEST(c.conkey) WITH ORDINALITY AS u(attnum, attposition) ON TRUE
JOIN pg_class tbl ON tbl.oid = c.conrelid
JOIN pg_namespace sch ON sch.oid = tbl.relnamespace
JOIN pg_attribute col ON (col.attrelid = tbl.oid AND col.attnum = u.attnum)
GROUP BY constraint_name, constraint_type, "schema", "table", definition
ORDER BY "schema", "table";
Hasil dipesan oleh schema
dan table
.
Catatan teknis: lihat pertanyaan ini tentang with ordinality
.
Baru-baru ini harus mengimplementasikan ini untuk Lapisan Akses Data yang membangun utilitas CRUD berdasarkan skema info, akhirnya dengan 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
"pg_constraint".contype IN ( 'f', 'p' )
AND
"pg_namespace".nspname = current_schema()
AND
"pg_constraint".conrelid::regclass::text IN ('whatever_table_name')
WHERE contype IN ('f', 'p', 'u')