61、对于employees表中，给出奇数行的first_name

1、题目描述

对于employees表中，给出奇数行的first_name
CREATE TABLE `employees` (
`emp_no` int(11) NOT NULL,
`birth_date` date NOT NULL,
`first_name` varchar(14) NOT NULL,
`last_name` varchar(16) NOT NULL,
`gender` char(1) NOT NULL,
`hire_date` date NOT NULL,
PRIMARY KEY (`emp_no`));
输出格式:

first_name

Georgi

Chirstian

Anneke

Tzvetan

Saniya

Mary

2、代码

SELECT e1.first_name FROM 
  (SELECT e2.first_name, 
    (SELECT COUNT(*) FROM employees e3 
     WHERE e3.first_name <= e2.first_name) 
   AS rowid FROM employees e2) e1
WHERE e1.rowid % 2 = 1;