mysql查询无主键的表的方法：

查询无主键的表：
SELECT
	table_schema,
	table_name 
FROM
	information_schema.TABLES 
WHERE
	table_name NOT IN ( SELECT DISTINCT table_name FROM information_schema.COLUMNS WHERE column_key = "PRI" ) 
	AND table_schema IN ( 'caoss' );
	
查询无主键的表：
SELECT
	table_schema,
	table_name 
FROM
	information_schema.TABLES 
WHERE
	( table_schema, table_name ) NOT IN ( SELECT DISTINCT table_schema, table_name FROM information_schema.COLUMNS WHERE COLUMN_KEY = 'PRI' ) 
	AND table_schema NOT IN ( 'sys', 'mysql', 'information_schema', 'performance_schema' );