php - 联接mySQL表时如何从主键和外键获取值？

我有两张桌子，employee是父母，license是孩子。他们都有一个Lic_ID列作为参考，这个列是PK中的license和FK中的employee。license表还有一列Lic_Type用于保存许可证的名称。
我正在尝试创建一个带有列表框的表，以便可以更新employee表。列表框value需要用license.Lic_ID填充，license.Lic_Type将显示在option中。以下是我所拥有的：

(Employee name, Id, etc. called out up here)

<?php
echo "<select name=\"Lic\">";
echo "<option value=\"\">Select...</option>";

$sql = $mysqli->query("SELECT Lic_ID, Lic_Type FROM license");

while($row = $result->fetch_assoc())
     {
     echo "<option value=\"" . $row['Lic_ID'] . "\">" . $row['Lic_Type'] . "</option>";
     }

echo "</select>";
?>

这样很好，它显示了许可证类型，并将值设置为许可证id。如果为员工设置了许可证id，我要做的是<option selected="selected">。这段代码不起作用，但我想它说明了我要做的：

<?php
echo "<select name=\"Lic\">";
echo "<option value=\"\">Select...</option>";

$sql = $mysqli->query("SELECT license.Lic_ID, license.Lic_Type, employee.Lic_ID FROM employee INNER JOIN license ON employee.Lic_ID = license.Lic_ID");

while($row = $result->fetch_assoc())
     {
     echo "<option value=\"" . $row['license.Lic_ID'] . "\"";
         if($row['employee.Lic_ID'] = $row['license.Lic_ID']){echo "selected=\"selected\";}
     echo ">" . $row['license.Lic_Type'] . "</option>";
     }

echo "</select>";
?>

有没有办法完成我想做的事？

最佳答案

我想我到底想完成什么可能有些困惑，我很抱歉没有说清楚。不管怎样，我今天无意中找到了答案，所以我想我应该把它贴出来。

$sql1 = ("SELECT Emp_Name, Lic_MAT_ID FROM employee");

if(!$result_employee_query = $mysqli->query($sql1))
    {
    die ("There was an error getting the records from the employee table");
    }

while($employee = $result_employee_query->fetch_assoc())
    {
    echo "Employee Name: " . $employee['Emp_Name'] . "<br>";

    echo "License: ";
    echo "<select>";

    $sql2 = ("SELECT Lic_MAT_ID, Lic_MAT_Type FROM license_mat");

    if(!$result_license_query = $mysqli->query($sql2))
        {
        die ("There was an error getting the records from the license table");
        }

    while($license = $result_license_query->fetch_assoc())
        {
        echo "<option value=\"" . $license ['Lic_MAT_ID'] . "\"";
            if($license['Lic_MAT_ID'] == $employee['Lic_MAT_ID'])
                {
                echo " selected=\"selected\"";
                }
        echo ">" . $license ['Lic_MAT_Type'] . "</option>";
        }

    echo "</select><br>";
    }

关于php - 联接mySQL表时如何从主键和外键获取值？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/13447723/