如何在 PostgreSQL 中列出表的所有约束？

Question

如何在 PostgreSQL 中列出表的所有约束（主键、外键、检查、唯一互斥、..）？

Answer 1

这是 POSTGRES 的具体答案 ......它将检索所有列及其关系

SELECT * FROM (

SELECT
    pgc.contype as constraint_type,
    pgc.conname as constraint_name,
    ccu.table_schema AS table_schema,
    kcu.table_name as table_name,
    CASE WHEN (pgc.contype = 'f') THEN kcu.COLUMN_NAME ELSE ccu.COLUMN_NAME END as column_name, 
    CASE WHEN (pgc.contype = 'f') THEN ccu.TABLE_NAME ELSE (null) END as reference_table,
    CASE WHEN (pgc.contype = 'f') THEN ccu.COLUMN_NAME ELSE (null) END as reference_col,
    CASE WHEN (pgc.contype = 'p') THEN 'yes' ELSE 'no' END as auto_inc,
    CASE WHEN (pgc.contype = 'p') THEN 'NO' ELSE 'YES' END as is_nullable,

        'integer' as data_type,
        '0' as numeric_scale,
        '32' as numeric_precision
FROM
    pg_constraint AS pgc
    JOIN pg_namespace nsp ON nsp.oid = pgc.connamespace
    JOIN pg_class cls ON pgc.conrelid = cls.oid
    JOIN information_schema.key_column_usage kcu ON kcu.constraint_name = pgc.conname
    LEFT JOIN information_schema.constraint_column_usage ccu ON pgc.conname = ccu.CONSTRAINT_NAME 
    AND nsp.nspname = ccu.CONSTRAINT_SCHEMA
 
 UNION
 
    SELECT  null as constraint_type , null as constraint_name , 'public' as "table_schema" ,
    table_name , column_name, null as refrence_table , null as refrence_col , 'no' as auto_inc ,
    is_nullable , data_type, numeric_scale , numeric_precision
    FROM information_schema.columns cols 
    Where 1=1
    AND table_schema = 'public'
    and column_name not in(
        SELECT CASE WHEN (pgc.contype = 'f') THEN kcu.COLUMN_NAME ELSE kcu.COLUMN_NAME END 
        FROM
        pg_constraint AS pgc
        JOIN pg_namespace nsp ON nsp.oid = pgc.connamespace
        JOIN pg_class cls ON pgc.conrelid = cls.oid
        JOIN information_schema.key_column_usage kcu ON kcu.constraint_name = pgc.conname
        LEFT JOIN information_schema.constraint_column_usage ccu ON pgc.conname = ccu.CONSTRAINT_NAME 
        AND nsp.nspname = ccu.CONSTRAINT_SCHEMA
    )
)   as foo

ORDER BY table_name desc
    

Answer 2

可以从catalog-pg-constraint 中检索表的约束。使用SELECT查询。

SELECT con.*
    FROM pg_catalog.pg_constraint con
        INNER JOIN pg_catalog.pg_class rel ON rel.oid = con.conrelid
        INNER JOIN pg_catalog.pg_namespace nsp ON nsp.oid = connamespace
        WHERE nsp.nspname = '{schema name}'
             AND rel.relname = '{table name}';

同样可以在PSQL使用中查看

\d+ {SCHEMA_NAME.TABLE_NAME}

Answer 3

我无法使上述解决方案发挥作用。也许他们不再受到支持，或者更有可能是我做错了什么。这就是我让它发挥作用的方式。请注意，“contype”列将缩写为约束类型（例如，“c”表示检查，“p”表示主键等）。我包含该变量，以防您想在 FROM 块之后添加 WHERE 语句来过滤它。

select pgc.conname as constraint_name,
       ccu.table_schema as table_schema,
       ccu.table_name,
       ccu.column_name,
       contype,
        pg_get_constraintdef(pgc.oid)
from pg_constraint pgc
         join pg_namespace nsp on nsp.oid = pgc.connamespace
         join pg_class  cls on pgc.conrelid = cls.oid
         left join information_schema.constraint_column_usage ccu
                   on pgc.conname = ccu.constraint_name
                       and nsp.nspname = ccu.constraint_schema
order by pgc.conname;

Answer 4

这是获取 PostgreSQL 中表的所有约束的简单方法

SELECT constraint_name, table_name, column_name, ordinal_position FROM information_schema.key_column_usage WHERE table_name = '<your_table_name>';