| title | date | tags | categories | mathjax |
|---|---|---|---|---|
Excel文件导入导出和实战 |
2019-03-03 05:44:14 -0800 |
SQL |
SQL |
true |
Excel文件导入到Mysql，以及Mysql导出到本地文件中。最后附加三个练习题！
首先创建一个对应的表格Employee，然后右键点击刷新，会出现下图中的Employee表格。
其次，右键Employee表格，点击导入向导，出现下图：
然后，选择需要导入的文件类型，这里选择xlsx；再，选择源文件和表格：
设置起始行等：
确定目标表和源表：
选择源表的具体列（如果源表列名与目标表列名相同，会设置为默认）：
点击下一步，选择添加模式：
点击开始，进行导入
显示成功：
从上面导入的表格数据中导出所有数据：
选择源表，和本地的目标表格：
确定源表：
附加选项
点击开始
导出成功：
创建Employee 表，包含所有员工信息，每个员工有其对应的 Id, salary 和 department Id。
+----+-------+--------+--------------+
| Id | Name | Salary | DepartmentId |
+----+-------+--------+--------------+
| 1 | Joe | 70000 | 1 |
| 2 | Henry | 80000 | 2 |
| 3 | Sam | 60000 | 2 |
| 4 | Max | 90000 | 1 |
+----+-------+--------+--------------+
创建Department 表，包含公司所有部门的信息。
+----+----------+
| Id | Name |
+----+----------+
| 1 | IT |
| 2 | Sales |
+----+----------+
编写一个 SQL 查询，找出每个部门工资最高的员工。例如，根据上述给定的表格，Max 在 IT 部门有最高工资，Henry 在 Sales 部门有最高工资。
+------------+----------+--------+
| Department | Employee | Salary |
+------------+----------+--------+
| IT | Max | 90000 |
| Sales | Henry | 80000 |
+------------+----------+--------+
CREATE TABLE Department (Id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
Name VARCHAR(10));
CREATE TABLE Employee (Id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
Name VARCHAR(10), Salary BIGINT, DepartmentId INT NOT NULL);
INSERT INTO Employee (Id, Name, Salary, DepartmentId) VALUES
(1, "Joe", 70000, 1),
(2, "Henry", 80000, 2),
(3, "Sam", 60000, 2),
(4, "Max", 90000, 1);
INSERT INTO Department (Id, Name) VALUES
(1, "IT"),
(2, "Sales");
SELECT d.Name Department, e.Name Employee, Salary
FROM Employee e, Department d
WHERE e.DepartmentId = d.Id
AND Salary IN (SELECT MAX(Salary)
FROM Employee, Department
WHERE DepartmentId = Department.Id
GROUP BY Department.Id);
小美是一所中学的信息科技老师，她有一张 seat 座位表，平时用来储存学生名字和与他们相对应的座位 id。其中纵列的 id 是连续递增的小美想改变相邻俩学生的座位。你能不能帮她写一个 SQL query 来输出小美想要的结果呢？
请创建如下所示seat表：示例：
+---------+---------+
| id | student |
+---------+---------+
| 1 | Abbot |
| 2 | Doris |
| 3 | Emerson |
| 4 | Green |
| 5 | Jeames |
+---------+---------+
假如数据输入的是上表，则输出结果如下：
+---------+---------+
| id | student |
+---------+---------+
| 1 | Doris |
| 2 | Abbot |
| 3 | Green |
| 4 | Emerson |
| 5 | Jeames |
+---------+---------+
注意：如果学生人数是奇数，则不需要改变最后一个同学的座位。
--创建表
CREATE TABLE seat (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
student VARCHAR(20));
--插入数据
INSERT INTO seat (id, student) VALUES
(1, "Abbot"),
(2, "Doris"),
(3, "Emerson"),
(4, "Green"),
(5, "Jeames");
--方法一
SELECT a.id, a.student
FROM
(
SELECT id-1 as id,student
FROM seat
WHERE id%2=0
UNION
SELECT id+1 as id,student
FROM seat
WHERE id%2=1 AND id != (SELECT MAX(id) FROM seat)
UNION
SELECT id,student
FROM seat
WHERE id%2=1 AND id = (SELECT MAX(id) FROM seat)
)a
ORDER BY a.id;
--方法二
SELECT (CASE
WHEN id % 2 != 0 AND id != counts THEN id+1
WHEN id % 2 != 0 AND id = counts THEN id
ELSE id-1
END) AS id, student
FROM seat,
(SELECT COUNT(*) counts FROM seat) as seat_count
ORDER BY id;
编写一个 SQL 查询来实现分数排名。如果两个分数相同，则两个分数排名（Rank）相同。请注意，平分后的下一个名次应该是下一个连续的整数值。换句话说，名次之间不应该有“间隔”。
创建以下score表：
+----+-------+
| Id | Score |
+----+-------+
| 1 | 3.50 |
| 2 | 3.65 |
| 3 | 4.00 |
| 4 | 3.85 |
| 5 | 4.00 |
| 6 | 3.65 |
+----+-------+
例如，根据上述给定的 Scores 表，你的查询应该返回（按分数从高到低排列）：
+-------+------+
| Score | Rank |
+-------+------+
| 4.00 | 1 |
| 4.00 | 1 |
| 3.85 | 2 |
| 3.65 | 3 |
| 3.65 | 3 |
| 3.50 | 4 |
+-------+------+
--创建表
CREATE TABLE score (Id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
Score DOUBLE);
--插入数据
INSERT INTO score (Id, Score) VALUES
(1, 3.50),
(2, 3.65),
(3, 4.00),
(4, 3.85),
(5, 4.00),
(6, 3.65);
SELECT Score,
(SELECT COUNT(Score) + 1
FROM score WHERE Score > s.Score)
AS Rank
FROM score s
ORDER BY Score DESC;
