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left join 运算是（）。
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用SQL语句进行表的查询操作，使用 ()语句。如果要进行分组查询，应使用 ()子句;如果要对查询结果进行排序，要使用 () 子句;查询使用连接操作时，可以使用的外连接方式主要有左连接() ，右连接() ，全连接 () 等几种。A UPDATE ， ORDER BY， GROUP BY， LEFT JOIN， RIGHT JOIN， FULL JOINB SELECT ， GROUP BY， ORDER BY， LEFT JOIN，RIGHT JOIN， FULL JOINC SELECT ， ORDER BY ， GROUP BY ， LEFT JOIN， RIGHT JOIN，FULL JOIND SELECT ，GROUP BY ， ORDER BY ， RIGHT JOIN， LEFT JOIN， FULL JOIN
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根据SQL标准，查询表student(sno,sname,sex,dept)中所有学生的选修课程数，其中选修记录在表SC(sno,cno,grade)中，两表中sno为关联字段。下面哪条语句合适?()A select sno,count(cno) from SCB select sno,count(cno) from studentC select a.sno,count(cno) from student a left outer join SCD select a.sno,count(cno) from SC left outer join student a
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ExhibitExamine the data in the EMPLOYEES and DEPARTMENTS tables.You want to retrieve all employees‘ last names, along with their manager‘s last names and their department names. Which query would you use?（）A. SELECT last_name, manager_id, department_name FROM employees e FULL OUTER JOIN department d ON (e.department_id = d.department_id);B. SELECT e.last_name, m.last_name, department_name FROM employees e LEFT OUTER JOIN employees m on ( e.managaer_id = m.employee_id) LEFT OUTER JOIN department d ON (e.department_id = d.department_id);C. SELECT e.last_name, m.last_name, department_name FROM employees e RIGT OUTER JOIN employees m on ( e.manager_id = m.employee_id) FULL OUTER JOIN department d ON (e.department_id = d.department_id);D. SELECT e.last_name, m.last_name, department_name FROM employees e LEFT OUTER JOIN employees m on ( e.manager_id = m.employee_id) RIGT OUTER JOIN department d ON (e.department_id = d.department_id);E. SELECT e.last_name, m.last_name, department_name FROM employees e RIGHT OUTER JOIN employees m on ( e.manager_id = m.employee_id) RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id)F. SELECT last_name, manager_id, department_name FROM employees e JOIN department d ON (e.department_id = d.department_id);
考题
Click the Exhibit button and examine the data in the EMPLOYEES and DEPARTMENTS tables.You want to retrieve all employees‘ last names, along with their managers‘ last names and their department names. Which query would you use?（）A.SELECT last_name, manager_id, department_name FROM employees e FULL OUTER JOIN departments d ON (e.department_id = d.department_id);B.SELECT e.last_name, m.last_name, department_name FROM employees e LEFT OUTER JOIN employees m on ( e.manager_id = m.employee_id) LEFT OUTER JOIN departments d ON (e.department_id = d.department_id);C.SELECT e.last_name, m.last_name, department_name FROM employees e RIGHT OUTER JOIN employees m on ( e.manager_id = m.employee_id) LEFT OUTER JOIN departments d ON (e.department_id = d.department_id);D.SELECT e.last_name, m.last_name, department_name FROM employees e LEFT OUTER JOIN employees m on ( e.manager_id = m.employee_id) RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);E.SELECT e.last_name, m.last_name, department_name FROM employees e RIGHT OUTER JOIN employees m on ( e.manager_id = m.employee_id) RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);F.SELECT last_name, manager_id, department_name FROM employees e JOIN departments d ON (e.department_id = d.department_id) ;
考题
设某数据库中有学生表（学号，姓名，所在系）和选课表（学号，课程号，成绩）。现要查询没选课的学生姓名和所在系。下列语句中能够实现该查询要求的是（ ）。A.SELECT姓名，所在系FROM学生表a LEFT JOIN选课表bON a．学号=b．学号WHERE a．学号IS NULLB.SELECT姓名，所在系FROM学生表a LEFT JOIN选课表bON a．学号=b．学号WHERE b．学号IS NULLC.SELECT姓名，所在系FROM学生表a RIGHT JOIN选课表bON a．学号=b．学号WHERE a．学号IS NULLD.SELECT姓名，所在系FROM学生表a RIGHT JOIN选课表bON a．学号=b．学号WHERE b．学号IS NULL
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Not a single word __________when he was forced to leave home and join the army in 1937.
A．did Mark leave
B．left Mark
C．did leave Mark
D．Mark left
考题
给定关系模式如下，学生（学号，姓名，专业），课程（课程号，课程名称），选课（学号，课程号，成绩）。查询所有学生的选课情况的操作是（ ）;查询所有课程的选修情况的操作是（请作答此空）。A.选课JOIN课程
B.选课LEFT JOIN课程
C.选课RIGHT JOIN课程
D.选课FULL JOIN课程
考题
使用下列（）命令可以使结果表中除了匹配行外，还包括右表有的但左表中不匹配的行。A、LEFT OUTER JOINB、RIGHT OUTER JOINC、NATURAL JOIND、INNER JOIN
考题
关于HQL的连接查询，说法错误的是（）。A、inner join 或 join用于内连接B、inner join fetch或 join fetch用于迫切内连接C、left outer join fetch 或 left join fetch用于迫切左外连接D、right outer join fetch 或 right join fetch用于迫切右外连接
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使用下列哪个命令可以使结果表中除了匹配行外，还包括右表有的但左表中不匹配的行？（）A、LEFT OUTER JOINB、RIGHT OUTER JOINC、NATURAL JOIND、INNER JOIN
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对于表A（col1 int，col2 char（1）），表B（col1 int，col2char（1）），为确保表A的数据全部被保留，下面正确的联接方式是（）A、A inner join BB、A left join BC、A right join BD、Across join B
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以下哪两组联接关键字可以创建这样一个联接，该联接包括SELECT语句中指定的第一个表中的不匹配行？（）A、LEFT OUTER JOIN和FULL OUTER JOINB、RIGHTOUTERJOIN和LEFT OUTER JOINC、USING和HAVINGD、OUTER JOIN和USING
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Click the Exhibit button and examine the data in the EMPLOYEES and DEPARTMENTS tables.You want to retrieve all employees, whether or not they have matching departments in the departments table. Which query would you use?（）A、SELECT last_name, department_name FROM employees NATURAL JOIN departments;B、SELECT last_name, department_name FROM employees JOIN departments ;C、SELECT last_name, department_name FROM employees e JOIN departments d ON (e.department_id = d.department_id);D、SELECT last_name, department_name FROM employees e RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);E、SELECT last_name, department_name FROM employees FULL JOIN departments ON (e.department_id = d.department_id);F、SELECT last_name, department_name FROM employees e LEFT OUTER JOIN departments d ON (e.department_id = d.department_id);
考题
单选题对于表A（col1 int，col2 char（1）），表B（col1 int，col2char（1）），为确保表A的数据全部被保留，下面正确的联接方式是（）A
A inner join BB
A left join BC
A right join BD
Across join B
考题
单选题“客户”表和“贷款”表的结构如下：客户（客户号，姓名，出生日期，身份证号）贷款（贷款编号，银行号，客户号，贷款金额，贷款性质）如果要检索从来没有贷过款的客户信息，正确的SQL语句是（ ）。A
SELECT客户.*FROM客户LEFT JOIN贷款；ON客户.客户号=贷款.客户号WHERE贷款.客户号=NULLB
SELECT客户.*FROM客户LEFT JOIN贷款；ON客户.客户号=贷款.客户号WHERE贷款.客户号IS NULLC
SELECT客户.*FROM客户RIGHT JOIN贷款；ON客户.客户号=贷款.客户号WHERE贷款.客户号=NULLD
SELECT客户.*FROM客户RIGHT JOIN贷款；ON客户.客户号=贷款.客户号WHERE贷款.客户号IS NULL
考题
单选题关于HQL的连接查询，说法错误的是（）。A
inner join 或 join用于内连接B
inner join fetch或 join fetch用于迫切内连接C
left outer join fetch 或 left join fetch用于迫切左外连接D
right outer join fetch 或 right join fetch用于迫切右外连接
考题
( 难度：中等)多表关联时，以左表为主体进行关联所使用的关键字是？A.RIGHT JOINB.INNER JOINC.ANDD.LEFT_JOIN
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