mysql 获取所有表的主键字段和约束字段

-- 获取所有表或指定表的主键
SELECT
	O.CONSTRAINT_SCHEMA,
	O.TABLE_NAME,
	O.COLUMN_NAME 
FROM
	(
		SELECT
		-- T.TABLE_COMMENT, -- 表注释
		K.CONSTRAINT_SCHEMA,
		K.CONSTRAINT_NAME,-- 约束名
		K.TABLE_SCHEMA,-- 拥有者
		K.TABLE_NAME,-- 子表名称
		K.COLUMN_NAME,-- 子表字段
		K.REFERENCED_TABLE_SCHEMA,
		K.REFERENCED_TABLE_NAME,-- 父表名称
		K.REFERENCED_COLUMN_NAME,-- 父表字段
		R.UPDATE_RULE,-- 约束更新规则
		R.DELETE_RULE,-- 约束删除规则
		R.UNIQUE_CONSTRAINT_NAME 
	FROM
		information_schema.KEY_COLUMN_USAGE K
		LEFT JOIN information_schema.REFERENTIAL_CONSTRAINTS R ON K.CONSTRAINT_NAME = R.CONSTRAINT_NAME 
	) AS O
	INNER JOIN Information_schema.TABLE_CONSTRAINTS T ON O.Table_Name = T.TABLE_NAME 
	AND T.CONSTRAINT_NAME = O.CONSTRAINT_NAME 
WHERE
	O.CONSTRAINT_SCHEMA != 'mysql' 
	AND O.CONSTRAINT_SCHEMA = database()
	AND O.TABLE_NAME = 'sys_group' 
GROUP BY
	O.COLUMN_NAME;