1. 基本描述

  本章讲解SELECT语句的各个组成部分及它们之间是如何相互作用的。

2. 基本样例

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SELECT emp_id, fname, lname FROM employee  WHERE lname = 'Bkadfl';  SELECT fname, lname FROM employee;  SELECT * FROM department;  SELECT dept_id, name FROM department;  SELECT name FROM department;  SELECT emp_id, 'ACTIVE', emp_id * 3.14159, UPPER(lname) FROM employee;  SELECT VERSION(), USER(), DATABASE();  SELECT emp_id, 'ACTIVE' status, emp_id * 3.14159 empid_x_pi, UPPER(lname) last_name_upper FROM employee;  SELECT emp_id, 'ACTIVE' AS status, emp_id * 3.14159 AS empid_x_pi, UPPER(lname) AS last_name_upper FROM employee;  SELECT cust_id FROM account;  SELECT DISTINCT cust_id FROM account;  SELECT e.emp_id, e.fname, e.lname FROM (SELECT emp_id, fname, lname, start_date, title FROM employee) e;  CREATE VIEW employee_vw AS SELECT emp_id, fname, lname, YEAR(start_date) start_year FROM employee;  SELECT emp_id, start_year FROM employee_vw;  SELECT employee.emp_id, employee.fname, employee.lname, department.name dept_name  FROM employee INNER JOIN department ON employee.dept_id = department.dept_id;  SELECT emp_id, fname, lname, start_date, title FROM employee WHERE title = 'Head Teller';  SELECT emp_id, fname, lname, start_date, title FROM employee WHERE title = 'Head Teller' AND start_date > '2006-01-01';  SELECT emp_id, fname, lname, start_date, title FROM employee WHERE title = 'Head Teller<