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  • 第五章 多表查询

    1.基本描述

        本章主要讲解内连接,INNER JOIN子句将一个表中的行于其他标表中的行进行匹配,并允许从两个表中查询包含列的行纪录,一般出现在FROM子句之后。

    2.基本样例

    DESC employee;
    
    DESC department;
    
    SELECT e.fname, e.lname, d.name FROM employee e JOIN department d;
    
    SELECT e.fname, e.lname, d.name FROM employee e JOIN department d ON e.dept_id = d.dept_id;
    
    SELECT e.fname, e.lname, d.name FROM employee e INNER JOIN department d ON e.dept_id = d.dept_id;
    
    SELECT e.fname, e.lname, d.name FROM employee e INNER JOIN department d USING (dept_id);
    
    SELECT e.fname, e.lname, d.name FROM employee e, department d WHERE e.dept_id = d.dept_id;
    
    SELECT a.account_id, a.cust_id, a.open_date, a.product_cd FROM account a, branch b, employee e
    WHERE a.open_emp_id = e.emp_id
    AND e.start_date < '2007-01-01'
    AND e.assigned_branch_id = b.branch_id
    AND (e.title = 'Teller' OR e.title = 'Head Teller')
    AND b.name = 'Woburn Branch';
    
    SELECT a.account_id, a.cust_id, a.open_date, a.product_cd FROM account a INNER JOIN employee e
    ON a.open_emp_id = e.emp_id
    INNER JOIN branch b
    ON e.assigned_branch_id = b.branch_id
    WHERE e.start_date < '2007-01-01'
    AND (e.title = 'Teller' OR e.title = 'Head Teller')
    AND b.name = 'Woburn Branch';
    
    SELECT a.account_id, c.fed_id FROM account a INNER JOIN customer c
    ON a.cust_id = c.cust_id WHERE c.cust_type_cd = 'B';
    
    SELECT a.account_id, c.fed_id, e.fname, e.lname FROM account a INNER JOIN customer c
    ON a.cust_id = c.cust_id
    INNER JOIN employee e
    ON a.open_emp_id = e.emp_id
    WHERE c.cust_type_cd = 'B';
    
    SELECT a.account_id, c.fed_id, e.fname, e.lname FROM customer c INNER JOIN account a
    ON e.emp_id = a.open_emp_id
    INNER JOIN customer c
    ON a.cust_id = c.cust_id
    WHERE c.cust_type_cd = 'B';
    
    SELECT emp_id, assigned_branch_id FROM employee
    WHERE start_date < '2007-01-01'
    AND (title = 'Teller' OR title = 'Head Teller');
    
    SELECT branch_id FROM branch 
    WHERE name = 'Woburn Branch';
    
    SELECT a.account_id, e.emp_id, b_a.name open_branch, b_e.name emo_branch
    FROM account a INNER JOIN branch b_a
    ON a.open_branch_id = b_a.branch_id
    INNER JOIN employee e
    ON a.open_emp_id = e.emp_id
    INNER JOIN branch b_e
    ON e.assigned_branch_id = b_e.branch_id
    WHERE a.product_cd = 'CHK';
    
    SELECT e.fname, e.lname, e_mgr.fname mgr_fname, e_mgr.lname mgr_lname
    FROM employee e INNER JOIN employee e_mgr
    ON e.superior_emp_id = e_mgr.emp_id;
    
    SELECT e1.fname, e1.lname, 'VS' vs, e2.fname, e2.lname
    FROM employee e1 INNER JOIN employee e2
    ON e1.emp_id != e2.emp_id
    WHERE e1.title = 'Teller' AND e2.title = 'Teller';
    
    SELECT e1.fname, e1.lname, 'VS' vs, e2.fname, e2.lname
    FROM employee e1 INNER JOIN employee e2
    ON e1.emp_id < e2.emp_id
    WHERE e1.title = 'Teller' AND e2.title = 'Teller';
    
    SELECT a.account_id, a.product_cd, c.fed_id FROM account a INNER JOIN customer c
    ON a.cust_id = c.cust_id
    WHERE c.cust_type_cd = 'B';
    
    SELECT a.account_id, a.product_cd, c.fed_id FROM account a INNER JOIN customer c
    ON a.cust_id = c.cust_id
    AND c.cust_type_cd = 'B';
    
    SELECT a.account_id, a.product_cd, c.fed_id FROM account a INNER JOIN customer c
    WHERE a.account_id = c.cust_id
    AND c.cust_type_cd = 'B';
    
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  • 原文地址:https://www.cnblogs.com/LuckPsyduck/p/12608221.html
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