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内连接:[inner|cross] join (不带inner或cross时也值内连接) 外连接: 左外连接:left [outer] join 右外连接:right [outer] join 语法: outer join full outer join mysql不支持全连接 全连接实现思路方法 select a.*,b.* from a left join b _disibledevent=>union select a.*,b.* from a right [阅读全文] [PDF]
="t18"> 还是先 Create table 吧 create table emp( id not null primary key, name varchar(10) ); create table emp_dept( dept_id varchar(4) not null, emp_id not null, emp_name varchar(10), primary key (dept_id,emp_id)); insert o emp values (1,"Dennis-1"), (2,"Dennis-2"), (3,"Dennis-3"), (4,"Dennis-4 [阅读全文] [PDF]
内连接:[inner|cross] join (不带inner或cross时也值内连接) 外连接: 左外连接:left [outer] join 右外连接:right [outer] join 错误语法: outer join full outer join mysql不支持全连接 全连接实现方法 select a.*,b.* from a left join b _disibledevent=b.id and a.id is null [阅读全文] [PDF]
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