在Oracle中,您可以使用以下查詢來獲取所需的資訊:
查詢主鍵索引資訊:
SELECT c.table_name, c.constraint_name AS index_name, LISTAGG(c.column_name, ', ') WITHIN GROUP (ORDER BY c.position) AS index_keys
FROM all_constraints c
WHERE c.constraint_type = 'P'
GROUP BY c.table_name, c.constraint_name;
查詢唯一索引資訊:
SELECT c.table_name, c.constraint_name AS index_name, LISTAGG(c.column_name, ', ') WITHIN GROUP (ORDER BY c.position) AS index_keys
FROM all_constraints c
WHERE c.constraint_type = 'U'
GROUP BY c.table_name, c.constraint_name;
查詢外來鍵約束資訊:
SELECT c.table_name, c.constraint_name, c.search_condition AS constraint_definition
FROM all_constraints c
WHERE c.constraint_type = 'R';
查詢約束資訊:
SELECT c.table_name, c.constraint_name, c.search_condition AS constraint_definition
FROM all_constraints c;
在PostgreSQL中,您可以使用以下查詢來獲取所需的資訊:
查詢主鍵索引資訊:
SELECT t.relname AS table_name, c.conname AS index_name, array_to_string(array_agg(a.attname), ', ') AS index_keys
FROM pg_class t
JOIN pg_constraint c ON t.oid = c.conrelid
JOIN pg_attribute a ON t.oid = a.attrelid AND a.attnum = ANY(c.conkey)
WHERE c.contype = 'p'
GROUP BY t.relname, c.conname;
查詢唯一索引資訊:
SELECT t.relname AS table_name, c.conname AS index_name, array_to_string(array_agg(a.attname), ', ') AS index_keys
FROM pg_class t
JOIN pg_constraint c ON t.oid = c.conrelid
JOIN pg_attribute a ON t.oid = a.attrelid AND a.attnum = ANY(c.conkey)
WHERE c.contype = 'u'
GROUP BY t.relname, c.conname;
查詢外來鍵約束資訊:
SELECT t.relname AS table_name, c.conname AS constraint_name, pg_get_constraintdef(c.oid) AS constraint_definition
FROM pg_class t
JOIN pg_constraint c ON t.oid = c.conrelid
WHERE c.contype = 'f';
查詢約束資訊:
SELECT t.relname AS table_name, c.conname AS constraint_name, pg_get_constraintdef(c.oid) AS constraint_definition
FROM pg_class t
JOIN pg_constraint c ON t.oid = c.conrelid;
以上查詢將按照表名、索引名、索引鍵(如果是複合索引,則會進行行轉列)的格式輸出所需的資訊。請注意,這些查詢基於Oracle和PostgreSQL的常規約定和命名規則,如果您的資料庫有特定的命名規則,可能需要進行相應的調整。
在關係型資料庫中,唯一索引和主鍵索引之間存在一定的關係。
主鍵索引是一種特殊的唯一索引,它用於唯一標識表中的每一行資料,並且不允許為空。主鍵索引的值必須是唯一的,而且對於每個表只能有一個主鍵索引。
唯一索引是用於確保表中某一列或一組列的值是唯一的索引。唯一索引允許空值,但對於非空值,它們必須是唯一的。
因此,可以說主鍵索引是唯一索引的一種特殊情況,它具有唯一性和非空性的特點。
為了在查詢結果中表現出這種關係,您可以將查詢語句稍作修改,新增一個欄位來標識索引型別。例如,在Oracle中查詢主鍵索引資訊時,您可以使用以下查詢:
SELECT c.table_name, c.constraint_name AS index_name, LISTAGG(c.column_name, ', ') WITHIN GROUP (ORDER BY c.position) AS index_keys, 'Primary Key' AS index_type
FROM all_constraints c
WHERE c.constraint_type = 'P'
GROUP BY c.table_name, c.constraint_name;
而在查詢唯一索引資訊時,可以使用以下查詢:
SELECT c.table_name, c.constraint_name AS index_name, LISTAGG(c.column_name, ', ') WITHIN GROUP (ORDER BY c.position) AS index_keys, 'Unique Index' AS index_type
FROM all_constraints c
WHERE c.constraint_type = 'U'
GROUP BY c.table_name, c.constraint_name;
類似地,在PostgreSQL中查詢主鍵索引和唯一索引資訊時,可以在查詢結果中新增一個欄位來標識索引型別。
這樣,查詢結果中的每一行將包含表名、索引名、索引鍵以及索引型別,以準確反映主鍵索引和唯一索引之間的關係。