解释下这段代码total_male_salary = 0 total_female_salary = 0 count_male = 0 count_female = 0

这段代码定义了四个变量：total_male_salary，total_female_salary，count_male，count_female。

total_male_salary和total_female_salary分别表示男性员工和女性员工的总薪资。

count_male和count_female分别表示男性员工和女性员工的数量。

这些变量的初始值都被设置为0。这段代码可能是为了在之后的程序中计算男性和女性员工的平均薪资而设立的。

相关问题

所有要求都是用sql sever语句实现 创建一个数据库，至少里面有5个表，每个表至少有十条数据，至少有两个表具有外键， 使用模式匹配查询，使用top查询，in查询，降序查询，使用count集合函数查询，分组统计查询，使用连接条件的多表查询，比较运算符的子查询，使用in的子查询 创建视图并使用 创建索引 创建唯一性约束，检查约束，默认值约束，外键约束 创建一个存储过程并使用 在某个表上创建一个插入和更新的dml触发器

好的，您的问题是如何用 SQL Server 实现创建一个数据库，其中包含5个表，每个表至少有10条数据，至少有两个表具有外键关系，以及其他的一些操作。下面是一个可能的实现：

首先，我们可以使用以下代码创建一个新的数据库：

CREATE DATABASE MyDatabase;

接下来，我们可以使用以下代码创建5个表，每个表包含10条数据：

USE MyDatabase;

-- 创建表1
CREATE TABLE Table1 (
    ID INT PRIMARY KEY,
    Name VARCHAR(50),
    Age INT,
    Gender VARCHAR(10),
    City VARCHAR(50)
);

INSERT INTO Table1 VALUES (1, 'John', 25, 'Male', 'New York');
INSERT INTO Table1 VALUES (2, 'Jane', 30, 'Female', 'Los Angeles');
INSERT INTO Table1 VALUES (3, 'Bob', 40, 'Male', 'Chicago');
INSERT INTO Table1 VALUES (4, 'Alice', 35, 'Female', 'Houston');
INSERT INTO Table1 VALUES (5, 'David', 28, 'Male', 'Miami');
INSERT INTO Table1 VALUES (6, 'Mary', 42, 'Female', 'San Francisco');
INSERT INTO Table1 VALUES (7, 'Tom', 27, 'Male', 'Seattle');
INSERT INTO Table1 VALUES (8, 'Lucy', 33, 'Female', 'Boston');
INSERT INTO Table1 VALUES (9, 'Peter', 45, 'Male', 'Dallas');
INSERT INTO Table1 VALUES (10, 'Susan', 29, 'Female', 'Washington');

-- 创建表2
CREATE TABLE Table2 (
    ID INT PRIMARY KEY,
    ProductName VARCHAR(50),
    Category VARCHAR(50),
    Price DECIMAL(10,2),
    SupplierID INT
);

INSERT INTO Table2 VALUES (1, 'iPhone', 'Electronics', 999.00, 1);
INSERT INTO Table2 VALUES (2, 'MacBook Pro', 'Electronics', 1999.00, 1);
INSERT INTO Table2 VALUES (3, 'Samsung Galaxy', 'Electronics', 799.00, 2);
INSERT INTO Table2 VALUES (4, 'Dell XPS', 'Electronics', 1499.00, 3);
INSERT INTO Table2 VALUES (5, 'Nike Air Max', 'Shoes', 129.00, 4);
INSERT INTO Table2 VALUES (6, 'Adidas Ultraboost', 'Shoes', 149.00, 4);
INSERT INTO Table2 VALUES (7, 'Levi\'s Jeans', 'Clothing', 59.00, 5);
INSERT INTO Table2 VALUES (8, 'Calvin Klein Underwear', 'Clothing', 29.00, 6);
INSERT INTO Table2 VALUES (9, 'Sony PlayStation', 'Gaming', 399.00, 7);
INSERT INTO Table2 VALUES (10, 'Microsoft Xbox', 'Gaming', 299.00, 7);

-- 创建表3
CREATE TABLE Table3 (
    ID INT PRIMARY KEY,
    OrderDate DATE,
    CustomerID INT,
    TotalAmount DECIMAL(10,2)
);

INSERT INTO Table3 VALUES (1, '2021-01-01', 1, 1000.00);
INSERT INTO Table3 VALUES (2, '2021-01-02', 2, 2000.00);
INSERT INTO Table3 VALUES (3, '2021-01-03', 3, 3000.00);
INSERT INTO Table3 VALUES (4, '2021-01-04', 4, 4000.00);
INSERT INTO Table3 VALUES (5, '2021-01-05', 5, 5000.00);
INSERT INTO Table3 VALUES (6, '2021-01-06', 6, 6000.00);
INSERT INTO Table3 VALUES (7, '2021-01-07', 7, 7000.00);
INSERT INTO Table3 VALUES (8, '2021-01-08', 8, 8000.00);
INSERT INTO Table3 VALUES (9, '2021-01-09', 9, 9000.00);
INSERT INTO Table3 VALUES (10, '2021-01-10', 10, 10000.00);

-- 创建表4
CREATE TABLE Table4 (
    ID INT PRIMARY KEY,
    EmployeeName VARCHAR(50),
    Department VARCHAR(50),
    Salary DECIMAL(10,2),
    ManagerID INT
);

INSERT INTO Table4 VALUES (1, 'John Smith', 'Sales', 5000.00, 2);
INSERT INTO Table4 VALUES (2, 'Jane Doe', 'Sales', 6000.00, 3);
INSERT INTO Table4 VALUES (3, 'Bob Johnson', 'Marketing', 7000.00, 4);
INSERT INTO Table4 VALUES (4, 'Alice Lee', 'Marketing', 8000.00, 5);
INSERT INTO Table4 VALUES (5, 'David Chen', 'Engineering', 9000.00, 6);
INSERT INTO Table4 VALUES (6, 'Mary Wang', 'Engineering', 10000.00, NULL);
INSERT INTO Table4 VALUES (7, 'Tom Liu', 'Finance', 11000.00, NULL);
INSERT INTO Table4 VALUES (8, 'Lucy Zhang', 'HR', 12000.00, 7);
INSERT INTO Table4 VALUES (9, 'Peter Wu', 'IT', 13000.00, 7);
INSERT INTO Table4 VALUES (10, 'Susan Zhao', 'IT', 14000.00, 8);

-- 创建表5
CREATE TABLE Table5 (
    ID INT PRIMARY KEY,
    CustomerName VARCHAR(50),
    Email VARCHAR(50),
    Phone VARCHAR(50),
    Address VARCHAR(50)
);

INSERT INTO Table5 VALUES (1, 'John', 'john@example.com', '123-456-7890', '123 Main St');
INSERT INTO Table5 VALUES (2, 'Jane', 'jane@example.com', '456-789-0123', '456 Oak Ave');
INSERT INTO Table5 VALUES (3, 'Bob', 'bob@example.com', '789-012-3456', '789 Pine St');
INSERT INTO Table5 VALUES (4, 'Alice', 'alice@example.com', '012-345-6789', '12 Maple Rd');
INSERT INTO Table5 VALUES (5, 'David', 'david@example.com', '345-678-9012', '345 Cedar St');
INSERT INTO Table5 VALUES (6, 'Mary', 'mary@example.com', '678-901-2345', '678 Elm St');
INSERT INTO Table5 VALUES (7, 'Tom', 'tom@example.com', '901-234-5678', '901 Walnut Ave');
INSERT INTO Table5 VALUES (8, 'Lucy', 'lucy@example.com', '234-567-8901', '234 Oak St');
INSERT INTO Table5 VALUES (9, 'Peter', 'peter@example.com', '567-890-1234', '567 Birch Rd');
INSERT INTO Table5 VALUES (10, 'Susan', 'susan@example.com', '890-123-4567', '890 Cherry St');

然后，我们可以使用以下代码创建两个具有外键关系的表：

-- 创建表6
CREATE TABLE Table6 (
    ID INT PRIMARY KEY,
    OrderID INT,
    ProductID INT,
    Quantity INT,
    Price DECIMAL(10,2),
    CONSTRAINT FK_Table6_OrderID FOREIGN KEY (OrderID) REFERENCES Table3(ID),
    CONSTRAINT FK_Table6_ProductID FOREIGN KEY (ProductID) REFERENCES Table2(ID)
);

INSERT INTO Table6 VALUES (1, 1, 1, 2, 1998.00);
INSERT INTO Table6 VALUES (2, 1, 2, 1, 1999.00);
INSERT INTO Table6 VALUES (3, 2, 3, 3, 2397.00);
INSERT INTO Table6 VALUES (4, 3, 4, 2, 2998.00);
INSERT INTO Table6 VALUES (5, 3, 5, 1, 129.00);
INSERT INTO Table6 VALUES (6, 4, 6, 2, 298.00);
INSERT INTO Table6 VALUES (7, 5, 7, 3, 177.00);
INSERT INTO Table6 VALUES (8, 6, 8, 1, 29.00);
INSERT INTO Table6 VALUES (9, 7, 9, 2, 798.00);
INSERT INTO Table6 VALUES (10, 8, 10, 1, 299.00);

-- 创建表7
CREATE TABLE Table7 (
    ID INT PRIMARY KEY,
    OrderID INT,
    EmployeeID INT,
    CONSTRAINT FK_Table7_OrderID FOREIGN KEY (OrderID) REFERENCES Table3(ID),
    CONSTRAINT FK_Table7_EmployeeID FOREIGN KEY (EmployeeID) REFERENCES Table4(ID)
);

INSERT INTO Table7 VALUES (1, 1, 1);
INSERT INTO Table7 VALUES (2, 2, 2);
INSERT INTO Table7 VALUES (3, 3, 3);
INSERT INTO Table7 VALUES (4, 4, 4);
INSERT INTO Table7 VALUES (5, 5, 5);
INSERT INTO Table7 VALUES (6, 6, 6);
INSERT INTO Table7 VALUES (7, 7, 7);
INSERT INTO Table7 VALUES (8, 8, 8);
INSERT INTO Table7 VALUES (9, 9, 9);
INSERT INTO Table7 VALUES (10, 10, 10);

接下来，我们可以使用以下代码来执行一些常见的查询操作：

USE MyDatabase;

-- 模式匹配查询
SELECT * FROM Table1 WHERE Name LIKE 'J%';

-- Top查询
SELECT TOP 5 * FROM Table2;

-- In查询
SELECT * FROM Table2 WHERE Category IN ('Electronics', 'Shoes');

-- 降序查询
SELECT * FROM Table4 ORDER BY Salary DESC;

-- Count集合函数查询
SELECT COUNT(*) FROM Table5 WHERE Address LIKE '%St';

-- 分组统计查询
SELECT Department, AVG(Salary) AS AvgSalary, COUNT(*) AS NumEmployees FROM Table4 GROUP BY Department;

-- 使用连接条件的多表查询
SELECT Table1.Name, Table2.ProductName FROM Table1 INNER JOIN Table6 ON Table1.ID = Table6.OrderID INNER JOIN Table2 ON Table6.ProductID = Table2.ID;

-- 比较运算符的子查询
SELECT * FROM Table4 WHERE Salary > (SELECT AVG(Salary) FROM Table4);

-- 使用In的子查询
SELECT * FROM Table3 WHERE CustomerID IN (SELECT ID FROM Table5 WHERE Phone LIKE '%123%');

然后，我们可以使用以下代码来创建视图：

CREATE VIEW View1 AS
SELECT Table1.Name, Table2.ProductName, Table6.Quantity, Table6.Price 
FROM Table1 INNER JOIN Table6 ON Table1.ID = Table6.OrderID INNER JOIN Table2 ON Table6.ProductID = Table2.ID;

接下来，我们可以使用以下代码创建索引：

CREATE INDEX IX_Table2_Category ON Table2(Category);

然后，我们可以使用以下代码来创建约束：

-- 唯一性约束
ALTER TABLE Table5 ADD CONSTRAINT UQ_Table5_Email UNIQUE (Email);

-- 检查约束
ALTER TABLE Table2 ADD CONSTRAINT CK_Table2_Price CHECK (Price > 0);

-- 默认值约束
ALTER TABLE Table1 ADD CONSTRAINT DF_Table1_Age DEFAULT 18 FOR Age;

-- 外键约束
ALTER TABLE Table6 ADD CONSTRAINT FK_Table6_SupplierID FOREIGN KEY (SupplierID) REFERENCES Table2(ID);

接下来，我们可以使用以下代码创建一个存储过程：

CREATE PROCEDURE Proc1
AS
BEGIN
    SELECT * FROM Table3 WHERE TotalAmount > 5000;
END;

最后，我们可以使用以下代码为某个表创建一个插入和更新的DML触发器：

CREATE TRIGGER Trigger1 ON Table3
FOR INSERT, UPDATE
AS
BEGIN
    IF EXISTS(SELECT * FROM Table6 WHERE OrderID IN (SELECT ID FROM inserted))
    BEGIN
        PRINT 'An order has been updated or inserted.';
    END
END;