我有以下 SQL 代码,它返回数据库中的表以及每个表中的主键字段。
SELECT Keys.TABLE_NAME As 'Table Name',
Keys.COLUMN_NAME AS 'Primary Key'
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS Constraints
JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS Keys
ON Constraints.TABLE_NAME = Keys.TABLE_NAME
AND Constraints.CONSTRAINT_NAME = Keys.CONSTRAINT_NAME
WHERE Constraints.CONSTRAINT_TYPE = 'PRIMARY KEY'
事实上,它只显示那些具有主键的表。如何修改sql以显示所有表,而那些没有主键的表将在“主键”列中显示“null”?