如何列出PostgreSQL中表的所有约束？

问题描述 投票：0回答：6

如何列出 PostgreSQL 中表的所有约束（主键、外键、检查、唯一互斥、..）？

postgresql constraints
6个回答
35
投票

可以使用 SELECT 查询从 

catalog-pg-constraint 检索表的约束。

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}'; 
并且可以使用
在
PSQL
中查看相同内容

\d+ {SCHEMA_NAME.TABLE_NAME}

    



    

    
    
    

    

        

            

                

                    
11
投票

                    
                

            

        

        


这是 POSTGRES 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
    

    



    

    
    
    

    

        

            

                

                    
9
投票

                    
                

            

        

        
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>';

    



    

    
    
    

    

        

            

                

                    
7
投票

                    
                

            

        

        
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;

    



    

    
    
    

    

        

            

                

                    
0
投票

                    
                

            

        

        
这适用于当您想要获取
列名称+约束定义，按架构+表过滤。有点解决方法，但有效。

SELECT
    SUBSTRING(
        pg_get_constraintdef(con.oid) FROM 7
    ) as "check_definition",

    (REGEXP_MATCHES(
        SUBSTRING(pg_get_constraintdef(con.oid) FROM 7),
        'length\("([^"]+)"\)'
    ))[1] as "column_name"
    
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 = 'my_schema'
    AND rel.relname = 'my_table'
    AND contype = 'c'; --only "check" constraints

| check_definition                                                                | column_name        |
|---------------------------------------------------------------------------------|--------------------|
| (((length("User_Name") > 0) AND (length("User_Name") < 250)))                   | User_Name          |
| (((length("User_AccountNumber") > 0) AND (length("User_AccountNumber") < 250))) | User_AccountNumber |
| (((length("User_FirstName") > 0) AND (length("User_FirstName") < 250)))         | User_FirstName     |
| (((length("User_LastName") > 0) AND (length("User_LastName") < 250)))           | User_LastName      |
| (((length("User_PersonalEmail") > 0) AND (length("User_PersonalEmail") < 250))) | User_PersonalEmail |
| (((length("User_Phone") > 0) AND (length("User_Phone") < 250)))                 | User_Phone         |
| (((length("User_PlaceOfBirth") > 0) AND (length("User_PlaceOfBirth") < 250)))   | User_PlaceOfBirth  |
| (((length("User_WorkEmail") > 0) AND (length("User_WorkEmail") < 250)))         | User_WorkEmail     |

我的正则表达式假设在“文本长度约束”中查找列名称，结构类似于 
(((length("User_Name") > 0) AND (length("User_Name") < 250)))

    



    

    
    
    

    

        

            

                

                    
0
投票

                    
                

            

        

        
要动态生成创建具有所有约束的表的 PostgreSQL 脚本，您可以查询 PostgreSQL 系统目录表 (pg_catalog) 以提取有关列、主键、外键和检查约束的信息。


这是动态生成 CREATE TABLE 语句的完整脚本：


DO $$
DECLARE
    schema_name TEXT := 'public'; -- Replace with your schema name
    table_name TEXT := 'employees'; -- Replace with your table name
    column_def RECORD;
    pk_constraint RECORD;
    fk_constraint RECORD;
    check_constraint RECORD;
    create_table_query TEXT := '';
BEGIN
    -- Start CREATE TABLE statement
    create_table_query := format('CREATE TABLE IF NOT EXISTS %I.%I (\n', schema_name, table_name);

    -- Add columns
    FOR column_def IN 
        EXECUTE format(
            'SELECT column_name, data_type, character_maximum_length, numeric_precision, numeric_scale, is_nullable, column_default 
            FROM information_schema.columns 
            WHERE table_schema = %L AND table_name = %L',
            schema_name, table_name
        )
    LOOP
        create_table_query := create_table_query || 
            format('    %I %s%s%s%s,\n',
                column_def.column_name,
                CASE
                    WHEN column_def.data_type = 'character varying' THEN format('character varying(%s)', column_def.character_maximum_length)
                    WHEN column_def.data_type = 'numeric' THEN format('numeric(%s, %s)', column_def.numeric_precision, column_def.numeric_scale)
                    ELSE column_def.data_type
                END,
                CASE WHEN column_def.is_nullable = 'NO' THEN ' NOT NULL' ELSE '' END,
                CASE WHEN column_def.column_default IS NOT NULL THEN format(' DEFAULT %s', column_def.column_default) ELSE '' END,
                CASE WHEN column_def.data_type = 'character varying' THEN ' COLLATE pg_catalog."default"' ELSE '' END
            );
    END LOOP;

    -- Add primary key constraint
    FOR pk_constraint IN
        EXECUTE format(
            'SELECT conname, pg_get_constraintdef(oid, true) AS definition 
            FROM pg_constraint 
            WHERE conrelid = %L::regclass AND contype = %L',
            format('%I.%I', schema_name, table_name), 'p' -- 'p' = Primary Key
        )
    LOOP
        create_table_query := create_table_query || 
            format('    CONSTRAINT %I %s,\n', pk_constraint.conname, pk_constraint.definition);
    END LOOP;

    -- Add foreign key constraints
    FOR fk_constraint IN
        EXECUTE format(
            'SELECT conname, pg_get_constraintdef(oid, true) AS definition 
            FROM pg_constraint 
            WHERE conrelid = %L::regclass AND contype = %L',
            format('%I.%I', schema_name, table_name), 'f' -- 'f' = Foreign Key
        )
    LOOP
        create_table_query := create_table_query || 
            format('    CONSTRAINT %I %s,\n', fk_constraint.conname, fk_constraint.definition);
    END LOOP;

    -- Add check constraints
    FOR check_constraint IN
        EXECUTE format(
            'SELECT conname, pg_get_constraintdef(oid, true) AS definition 
            FROM pg_constraint 
            WHERE conrelid = %L::regclass AND contype = %L',
            format('%I.%I', schema_name, table_name), 'c' -- 'c' = Check Constraint
        )
    LOOP
        create_table_query := create_table_query || 
            format('    CONSTRAINT %I %s,\n', check_constraint.conname, check_constraint.definition);
    END LOOP;

    -- Remove last comma and close the statement
    create_table_query := regexp_replace(create_table_query, ',\n$', '\n');
    create_table_query := create_table_query || ');';

    -- Print the generated query
    RAISE NOTICE '%', create_table_query;
END $$;

    

	

    

    


  

  

    
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