如何通過plpgsql從Postgres獲取表的主鍵？

Question

給定一個表名，我如何從plpgsql函數中提取主鍵列及其數據類型的列表？

Answer 1

上面的查詢是非常糟糕的，因爲它實在是太慢了。

我會推薦這正式版：

http://wiki.postgresql.org/wiki/Retrieve_primary_key_columns

是否需要架構查詢是如下

SELECT    
    pg_attribute.attname, 
    format_type(pg_attribute.atttypid, pg_attribute.atttypmod) 
FROM pg_index, pg_class, pg_attribute, pg_namespace 
WHERE 
    pg_class.oid = 'foo'::regclass AND 
    indrelid = pg_class.oid AND 
    nspname = 'public' AND 
    pg_class.relnamespace = pg_namespace.oid AND 
    pg_attribute.attrelid = pg_class.oid AND 
    pg_attribute.attnum = any(pg_index.indkey) 
AND indisprimary 

Answer 2

看看pg_constraint系統表。或者如果您願意堅持接近SQL標準，則可以使用information_schema.table_constraints視圖。

有關完整示例，請使用帶「-E」選項的psql連接到數據庫，並鍵入\d <some_table> - 您將看到用於描述表的實際查詢。

Answer 3

提供SQL的直一點，你可以列出的主鍵列和它們的類型有：

SELECT 
c.column_name, c.data_type 
FROM 
information_schema.table_constraints tc 
JOIN information_schema.constraint_column_usage AS ccu USING (constraint_schema, constraint_name) 
JOIN information_schema.columns AS c ON c.table_schema = tc.constraint_schema AND tc.table_name = c.table_name AND ccu.column_name = c.column_name 
where constraint_type = 'PRIMARY KEY' and tc.table_name = 'mytable'; 

Answer 4

謹防指標，其中列的順序從表中的列的順序不同。 （即，如果主鍵使用，2列3和1）

以下查詢要複雜得多，但以適當的順序返回列。 （刪除「indisprimary」條款得到所有索引的相同信息上表）

WITH ndx_list AS 
(
    SELECT pg_index.indexrelid 
     FROM pg_index, pg_class 
    WHERE pg_class.relname = 'test_indices_table' 
     AND pg_class.oid = pg_index.indrelid 
     AND pg_index.indisprimary 
), ndx_cols AS 
(
    SELECT pg_class.relname AS index_name, UNNEST(i.indkey) AS col_ndx, i.indisunique, i.indisprimary 
    FROM pg_class, pg_index i 
    WHERE pg_class.oid = i.indexrelid 
     AND pg_class.oid IN (SELECT indexrelid FROM ndx_list) 
) 
    SELECT ndx_cols.index_name, ndx_cols.indisunique, ndx_cols.indisprimary, 
     a.attname, format_type(a.atttypid, a.atttypmod), a.attnum 
    FROM pg_class c, pg_attribute a 
    JOIN ndx_cols ON (a.attnum = ndx_cols.col_ndx) 
    WHERE c.oid = 'test_indices_table'::regclass 
    AND a.attrelid = c.oid 

Answer 5

保留使用generate_subscripts列順序：

SELECT 
    a.attname, 
    format_type(a.atttypid, a.atttypmod) 
FROM 
    pg_attribute a 
    JOIN (SELECT *, GENERATE_SUBSCRIPTS(indkey, 1) AS indkey_subscript FROM pg_index) AS i 
    ON 
     i.indisprimary 
     AND i.indrelid = a.attrelid 
     AND a.attnum = i.indkey[i.indkey_subscript] 
WHERE 
    a.attrelid = 'your_table'::regclass 
ORDER BY 
    i.indkey_subscript 

Answer 6

以下SQL語句對我的作品：

SELECT a.attname 
FROM pg_index i 
JOIN pg_attribute a ON a.attrelid = i.indrelid 
        AND a.attnum = ANY(i.indkey) 
WHERE i.indrelid = 'tablename'::regclass 
AND i.indisprimary; 

它是直接從here拍攝。