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:
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;