mysql 2个数据表关联查询

mysql 2个数据表关联查询(tableA,tableB)

select a,b from tableA,tableB where tableA.m = tableB.m

与

select a,b from tableA left join tableB on  tableA.m = tableB.m

与

select a,b from tableA left join tableB using (m)

的查询结果是相同的