摘要： 1. JoinTips:(1). Inner Join 同 JoinSelect alias_name1.column_name, alias_name2.column_nameFrom table_name1 as alias_name1Inner join table_name2 as alias_name2On alias_name1.column3 = alias_name2.column4Order by alias_name1.column_name1(2). Left Join, 即使右表没有匹配，也返回左表所有行Select alias_name1.column_name, a 阅读全文