SQL查询从当前日期检索字段

Question

这是我的数据库SQL代码;

CREATE TABLE ProductType 
(
    ptID int not null auto_increment, 
    pType varchar(30), 
    PRIMARY KEY(ptID) 
)ENGINE=InnoDB; 

CREATE TABLE Service 
(
    sID int not null auto_increment, 
    description varchar(30) not null, 
    revenue int, 
    stID int not null, 
    PRIMARY KEY(sID), 
    FOREIGN KEY(stID) references ServiceType(stID) 
)ENGINE=InnoDB; 

CREATE TABLE Product 
(
    pID int not null auto_increment, 
    model varchar(30) not null, 
    cogs int, 
    ptID int not null, 
    PRIMARY KEY(pID), 
    FOREIGN KEY(ptID) references ProductType(ptID) 
)ENGINE=InnoDB; 

CREATE TABLE Sale 
(
    saleID int not null auto_increment, 
    assetID int not null, 
    eID int not null, 
    sID int not null, 
    pID int, 
    saDate date not null, 
    PRIMARY KEY(saleID), 
    FOREIGN KEY(eID) references Employee(eID), 
    FOREIGN KEY(sID) references Service(sID), 
    FOREIGN KEY(pID) references Product(pID) 
)ENGINE=InnoDB; 

CREATE TABLE Employee 
(
    eID int not null auto_increment, 
    firstName varchar(30) not null, 
    lastName varchar(30) not null, 
    phone varchar(30), 
    email varchar(30), 
    PRIMARY KEY(eID) 
) 

这是我的尝试，但我不知道如何从“服务”当我查询“出售”表访问“收入”字段。

<?php 
// Make a MySQL Connection 
mysql_connect("localhost", "root", "root") or die(mysql_error()); 
mysql_select_db("pnl") or die(mysql_error()); 

// Retrieve all the data from the "example" table 
$result = mysql_query("SELECT * FROM Sale WHERE saDate = CURDATE()") 
or die(mysql_error()); 

// store the record of the "example" table into $row 
$row = mysql_fetch_array($result); 
// Print out the contents of the entry 

echo "revenue: ".$row['revenue']; 

?> 

谁能给我的，我怎么会写一个PHP脚本来检索所有的销售收入为当前日期的例子吗？这也是我第一次尝试SQL和关系数据库模型，所以如果你发现我犯的任何重大错误或者我可以改进的地方，请告诉我！

Answer 1

试试这个方法。命名SUM字段并按给定名称访问它：

// Retrieve all the data from the "example" table 
$result = mysql_query("SELECT SUM(Service.revenue) sum FROM Service JOIN Sale ON Sale.sID = Service.sID WHERE Sale.saDate = $some_date") or die(mysql_error()); 
// store the record of the "example" table into $row 
$row = mysql_fetch_array($result); 
// Print out the contents of the entry 
echo "revenue: ".$row['sum']; 

Answer 2

如果SID销售和服务都是相同的，独一无二的每一个销售，那么你可以使用这样的查询：

$result = mysql_query(SELECT Sale.saleID, Sale.assetID, Sale.eID, Sale.sID, Sale.pID, Sale.saDate, Service.revenue "."FROM Sale, Service "."WHERE Sale.sID = Service.sID AND Sale.saDate = CURDATE()) or die(mysql_error()); 

或者，如果Service.sID = Sale.saleID然后更改acordingly。

通过这种方式，您可以控制您想要从每个表中检索哪个列。