Question

这是示例查询-

self.eslTopics.isHidden = false

我得到的结果-

WITH empdata AS (SELECT xmltype ('<office>
                            <emp>
                                <empno>1</empno>
                                <ename>Abraham</ename>
                                <deptno>10</deptno>
                            </emp>
                            <emp>
                                <empno>2</empno>
                                <ename>Alexander</ename>
                                <deptno>10</deptno>
                            </emp>
                            <emp>
                                <empno>3</empno>
                                <ename>Benjamin</ename>
                                <deptno>20</deptno>
                            </emp>
                            <emp>
                                <empno>4</empno>
                                <ename>Bradley</ename>
                                <deptno>20</deptno>
                            </emp>
                         </office>') AS xcol FROM dual),
     dept AS
         (SELECT 10 deptno, 'Accounting' dname FROM dual
          UNION ALL
          SELECT 20, 'Broking' FROM dual
          UNION ALL
          SELECT 30, 'HR' FROM dual)
SELECT d.dname, e.ename, e.empno
  FROM dept d
       CROSS JOIN empdata e_data
       LEFT OUTER JOIN
       xmltable (
           'office/emp'
           PASSING e_data.xcol
           COLUMNS deptno NUMBER (28, 0) PATH 'deptno',
                   ename VARCHAR2 (10) PATH 'ename',
                   empno NUMBER (28, 0) PATH 'empno') e
           ON d.deptno = e.deptno;

为什么DNAME ENAME EMPNO ---------- ---------- ---------- Accounting Abraham 1 Accounting Alexander 2 Broking Benjamin 3 Broking Bradley 4中的第三行没有显示，即HR的第三行没有显示在结果集中？理想情况下，应根据LEFT JOIN的规则显示左侧表格中的所有记录。为什么那一个被过滤掉？

Answer 1

您的外部联接和交叉联接的方式错误。您需要将apply plugin: 'com.android.application' apply plugin: 'kotlin-android' apply plugin: 'kotlin-android-extensions' android { compileSdkVersion 27 defaultConfig { applicationId "com.test.myapplication" minSdkVersion 15 targetSdkVersion 27 versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } } dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation"org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" implementation 'com.android.support:appcompat-v7:27.1.1' implementation 'com.android.support.constraint:constraint-layout:1.1.2' implementation 'com.android.support:design:27.1.1' testImplementation 'junit:junit:4.12' androidTestImplementation 'com.android.support.test:runner:1.0.2' androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' }交叉连接到build.gradle作为子变量，并使用该子查询（内联视图）作为外部联接的目标：

empdata

使用XMLTABLE的LEFT OUTER JOIN不起作用吗？

1 个答案: