SQL查询查找表的主键？

Question

如何使用查询找到哪个列是表的主键？

Answer 1

这是一个重复的问题:

Lukmdo对这个答案的信任:

可能不建议但工作得很好:

show index from TABLE where Key_name = 'PRIMARY' ;

坚实的方法是使用information_schema:

SELECT k.COLUMN_NAME
FROM information_schema.table_constraints t
LEFT JOIN information_schema.key_column_usage k
USING(constraint_name,table_schema,table_name)
WHERE t.constraint_type='PRIMARY KEY'
    AND t.table_schema=DATABASE()
    AND t.table_name='owalog';

Answer 2

对于Oracle,您可以在ALL_CONSTRAINTS表中查找:

SELECT a.COLUMN_NAME
FROM all_cons_columns a INNER JOIN all_constraints c 
     ON a.constraint_name = c.constraint_name 
WHERE c.table_name = 'TBL'
  AND c.constraint_type = 'P';

演示.

对于SQL Server,它已在这里得到解答,对于MySQL,请查看@ ajon的答案.

Answer 3

对于MySQL:

SELECT GROUP_CONCAT(COLUMN_NAME), TABLE_NAME
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
  TABLE_SCHEMA = '**database name**'
  AND CONSTRAINT_NAME='PRIMARY'
GROUP BY TABLE_NAME;

警告具有两列的主键将它们用逗号(,)分隔

Answer 4

在SQL Server中尝试此查询:

SELECT     X.NAME AS INDEXNAME,
           COL_NAME(IC.OBJECT_ID,IC.COLUMN_ID) AS COLUMNNAME
FROM       SYS.INDEXES  X 
INNER JOIN SYS.INDEX_COLUMNS  IC 
        ON X.OBJECT_ID = IC.OBJECT_ID
       AND X.INDEX_ID = IC.INDEX_ID
WHERE      X.IS_PRIMARY_KEY = 1
  AND      OBJECT_NAME(IC.OBJECT_ID)='YOUR_TABLE'