http://blog.csdn.net/u011573853/article/details/51355113 在上面我们已经说了单表的一些操作,现在我们说一下多表的连接 from sqlalchemy import distinct from sqlalchemy.orm import aliased Astu = aliased(Stu, 'Astu' ) Acla = aliased(Cla, 'Acla'
http://blog.csdn.net/u011573853/article/details/51355113
在上面我们已经说了单表的一些操作,现在我们说一下多表的连接
<code class=" hljs python"><span class="hljs-prompt">>>> </span><span class="hljs-keyword">from</span> sqlalchemy <span class="hljs-keyword">import</span> distinct <span class="hljs-prompt">>>> </span><span class="hljs-keyword">from</span> sqlalchemy.orm <span class="hljs-keyword">import</span> aliased <span class="hljs-prompt">>>> </span>Astu = aliased(Stu,<span class="hljs-string">'Astu'</span>) <span class="hljs-prompt">>>> </span>Acla = aliased(Cla,<span class="hljs-string">'Acla'</span>) <span class="hljs-prompt">>>> </span>Agrade = aliased(Grade,<span class="hljs-string">'Agrade'</span>)</code>
在这里先用函数aliased()给表起一个别名以备使用
<code class=" hljs r"><span class="hljs-comment">#查询所有有成绩的学号</span> >>> query = session.query(Stu).join(Grade,Stu.id==Grade.uid).all() SELECT stu.id AS stu_id, stu.name AS stu_name FROM stu INNER JOIN grade ON stu.id = grade.uid <span class="hljs-number">2016</span>-<span class="hljs-number">05</span>-<span class="hljs-number">10</span> <span class="hljs-number">15</span>:<span class="hljs-number">02</span>:<span class="hljs-number">36</span>,<span class="hljs-number">476</span> INFO sqlalchemy.engine.base.Engine () >>> <span class="hljs-keyword">for</span> re <span class="hljs-keyword">in</span> query: <span class="hljs-keyword">...</span> print re.id <span class="hljs-keyword">...</span> <span class="hljs-number">1</span> <span class="hljs-number">2</span> <span class="hljs-number">3</span> <span class="hljs-number">4</span> <span class="hljs-number">5</span> >>> </code>
<code class=" hljs cpp"><span class="hljs-preprocessor">#查找有成绩的同学的学号好成绩</span> >>> print session.query(Grade.uid,Grade.gre).join(Stu,Grade.uid==Stu.id).all() SELECT grade.uid AS grade_uid, grade.gre AS grade_gre FROM grade INNER JOIN stu ON grade.uid = stu.id <span class="hljs-number">2016</span>-<span class="hljs-number">05</span>-<span class="hljs-number">10</span> <span class="hljs-number">15</span>:<span class="hljs-number">15</span>:<span class="hljs-number">22</span>,<span class="hljs-number">208</span> INFO sqlalchemy.engine.base.Engine () [(<span class="hljs-number">1L</span>, <span class="hljs-number">76L</span>), (<span class="hljs-number">1L</span>, <span class="hljs-number">76L</span>), (<span class="hljs-number">2L</span>, <span class="hljs-number">66L</span>), (<span class="hljs-number">2L</span>, <span class="hljs-number">76L</span>), (<span class="hljs-number">2L</span>, <span class="hljs-number">50L</span>), (<span class="hljs-number">3L</span>, <span class="hljs-number">96L</span>), (<span class="hljs-number">3L</span>, <span class="hljs-number">76L</span>), (<span class="hljs-number">3L</span>, <span class="hljs-number">60L</span>), (<span class="hljs-number">4L</span>, <span class="hljs-number">76L</span>), (<span class="hljs-number">4L</span>, <span class="hljs-number">76L</span>), (<span class="hljs-number">4L</span>, <span class="hljs-number">76L</span>), (<span class="hljs-number">5L</span>, <span class="hljs-number">66L</span>), (<span class="hljs-number">5L</span>, <span class="hljs-number">96L</span>), (<span class="hljs-number">5L</span>, <span class="hljs-number">96L</span>)] >>> </code>
<code class=" hljs oxygene">#查找有成绩同学的学好成绩和课程名 >>>print session.query(Grade.uid,Grade.gre,Cla.cname).<span class="hljs-keyword">join</span>(Stu,Grade.uid==Stuid).<span class="hljs-keyword">join</span>(Cla,Grade.cid==Cla.id).all() <span class="hljs-keyword">SELECT</span> grade.uid <span class="hljs-keyword">AS</span> grade_uid, grade.gre <span class="hljs-keyword">AS</span> grade_gre, cla.cname <span class="hljs-keyword">AS</span> cla_cname <span class="hljs-keyword">FROM</span> grade INNER <span class="hljs-keyword">JOIN</span> stu <span class="hljs-keyword">ON</span> grade.uid = stu.id INNER <span class="hljs-keyword">JOIN</span> cla <span class="hljs-keyword">ON</span> grade.cid = cla.id <span class="hljs-number">2016</span>-<span class="hljs-number">05</span>-<span class="hljs-number">10</span> <span class="hljs-number">15</span>:<span class="hljs-number">21</span>:<span class="hljs-number">29</span>,<span class="hljs-number">402</span> INFO sqlalchemy.engine.base.Engine () [(<span class="hljs-number">2</span>L, <span class="hljs-number">66</span>L, <span class="hljs-string">'yuwen'</span>), (<span class="hljs-number">5</span>L, <span class="hljs-number">66</span>L, <span class="hljs-string">'yuwen'</span>), (<span class="hljs-number">3</span>L, <span class="hljs-number">96</span>L, <span class="hljs-string">'shuxue'</span>), (<span class="hljs-number">2</span>L, <span class="hljs-number">50</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">3</span>L, <span class="hljs-number">60</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">4</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">5</span>L, <span class="hljs-number">96</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">1</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'wuli'</span>), (<span class="hljs-number">3</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'wuli'</span>), (<span class="hljs-number">4</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'wuli'</span>), (<span class="hljs-number">1</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'huaxue'</span>), (<span class="hljs-number">2</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'huaxue'</span>), (<span class="hljs-number">4</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'huaxue'</span>), (<span class="hljs-number">5</span>L, <span class="hljs-number">96</span>L, <span class="hljs-string">'huaxue'</span>)] >>> </code>
<code class=" hljs oxygene">#查找有成绩同学的学好成绩和课程名,并进行排序 >>> print session.query(Grade.uid,Grade.gre,Cla.cname).<span class="hljs-keyword">join</span>(Stu,Grade.uid==Stud).<span class="hljs-keyword">join</span>(Cla,Grade.cid==Cla.id).order_by(Grade.uid,Grade.gre.<span class="hljs-keyword">desc</span>()).all() <span class="hljs-keyword">SELECT</span> grade.uid <span class="hljs-keyword">AS</span> grade_uid, grade.gre <span class="hljs-keyword">AS</span> grade_gre, cla.cname <span class="hljs-keyword">AS</span> cla_cname <span class="hljs-keyword">FROM</span> grade INNER <span class="hljs-keyword">JOIN</span> stu <span class="hljs-keyword">ON</span> grade.uid = stu.id INNER <span class="hljs-keyword">JOIN</span> cla <span class="hljs-keyword">ON</span> grade.cid = cla.id <span class="hljs-keyword">ORDER</span> <span class="hljs-keyword">BY</span> grade.uid, grade.gre <span class="hljs-keyword">DESC</span> <span class="hljs-number">2016</span>-<span class="hljs-number">05</span>-<span class="hljs-number">10</span> <span class="hljs-number">15</span>:<span class="hljs-number">34</span>:<span class="hljs-number">17</span>,<span class="hljs-number">902</span> INFO sqlalchemy.engine.base.Engine () [(<span class="hljs-number">1</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'wuli'</span>), (<span class="hljs-number">1</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'huaxue'</span>), (<span class="hljs-number">2</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'huaxue'</span>), (<span class="hljs-number">2</span>L, <span class="hljs-number">66</span>L, <span class="hljs-string">'yuwen'</span>), (<span class="hljs-number">2</span>L, <span class="hljs-number">50</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">3</span>L, <span class="hljs-number">96</span>L, <span class="hljs-string">'shuxue'</span>), (<span class="hljs-number">3</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'wuli'</span>), (<span class="hljs-number">3</span>L, <span class="hljs-number">60</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">4</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">4</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'huaxue'</span>), (<span class="hljs-number">4</span>L, <span class="hljs-number">76</span>L, <span class="hljs-string">'wuli'</span>), (<span class="hljs-number">5</span>L, <span class="hljs-number">96</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">5</span>L, <span class="hljs-number">96</span>L, <span class="hljs-string">'huaxue'</span>), (<span class="hljs-number">5</span>L, <span class="hljs-number">66</span>L, <span class="hljs-string">'yuwen'</span>)] >>> </code>
或
<code class=" hljs avrasm">>>> query2=session<span class="hljs-preprocessor">.query</span>(Grade<span class="hljs-preprocessor">.uid</span>,Grade<span class="hljs-preprocessor">.gre</span>,Cla<span class="hljs-preprocessor">.cname</span>)<span class="hljs-preprocessor">.join</span>(Stu,Grade<span class="hljs-preprocessor">.uid</span>==Stid)<span class="hljs-preprocessor">.join</span>(Cla,Grade<span class="hljs-preprocessor">.cid</span>==Cla<span class="hljs-preprocessor">.id</span>)<span class="hljs-preprocessor">.order</span>_by(Grade<span class="hljs-preprocessor">.uid</span>,Grade<span class="hljs-preprocessor">.gre</span><span class="hljs-preprocessor">.desc</span>())<span class="hljs-preprocessor">.all</span>() SELECT grade<span class="hljs-preprocessor">.uid</span> AS grade_uid, grade<span class="hljs-preprocessor">.gre</span> AS grade_gre, cla<span class="hljs-preprocessor">.cname</span> AS cla_cname FROM grade INNER JOIN stu ON grade<span class="hljs-preprocessor">.uid</span> = stu<span class="hljs-preprocessor">.id</span> INNER JOIN cla ON grade<span class="hljs-preprocessor">.cid</span> = cla<span class="hljs-preprocessor">.id</span> ORDER BY grade<span class="hljs-preprocessor">.uid</span>, grade<span class="hljs-preprocessor">.gre</span> DESC <span class="hljs-number">2016</span>-<span class="hljs-number">05</span>-<span class="hljs-number">10</span> <span class="hljs-number">15</span>:<span class="hljs-number">37</span>:<span class="hljs-number">33</span>,<span class="hljs-number">628</span> INFO sqlalchemy<span class="hljs-preprocessor">.engine</span><span class="hljs-preprocessor">.base</span><span class="hljs-preprocessor">.Engine</span> () >>> for re <span class="hljs-keyword">in</span> query2: ... print re<span class="hljs-preprocessor">.uid</span>,re<span class="hljs-preprocessor">.gre</span>,re<span class="hljs-preprocessor">.cname</span> ... <span class="hljs-number">1</span> <span class="hljs-number">76</span> wuli <span class="hljs-number">1</span> <span class="hljs-number">76</span> huaxue <span class="hljs-number">2</span> <span class="hljs-number">76</span> huaxue <span class="hljs-number">2</span> <span class="hljs-number">66</span> yuwen <span class="hljs-number">2</span> <span class="hljs-number">50</span> yingyu <span class="hljs-number">3</span> <span class="hljs-number">96</span> shuxue <span class="hljs-number">3</span> <span class="hljs-number">76</span> wuli <span class="hljs-number">3</span> <span class="hljs-number">60</span> yingyu <span class="hljs-number">4</span> <span class="hljs-number">76</span> yingyu <span class="hljs-number">4</span> <span class="hljs-number">76</span> huaxue <span class="hljs-number">4</span> <span class="hljs-number">76</span> wuli <span class="hljs-number">5</span> <span class="hljs-number">96</span> yingyu <span class="hljs-number">5</span> <span class="hljs-number">96</span> huaxue <span class="hljs-number">5</span> <span class="hljs-number">66</span> yuwen >>> </code>
只需要把你要查的字段写在query()中就好了
<code class=" hljs oxygene">#查找成绩小于等于<span class="hljs-number">70</span>同学的学好成绩和课程名,并进行排序 >>>print session.query(Grade.uid,Grade.gre,Cla.cname).<span class="hljs-keyword">join</span>(Stu,Grade.uid==Stu.id).jn(Cla,Grade.cid==Cla.id).filter(Grade.gre<=<span class="hljs-number">70</span>).order_by(Grade.uid,Grade.gre.de()).all() <span class="hljs-keyword">SELECT</span> grade.uid <span class="hljs-keyword">AS</span> grade_uid, grade.gre <span class="hljs-keyword">AS</span> grade_gre, cla.cname <span class="hljs-keyword">AS</span> cla_cname <span class="hljs-keyword">FROM</span> grade INNER <span class="hljs-keyword">JOIN</span> stu <span class="hljs-keyword">ON</span> grade.uid = stu.id INNER <span class="hljs-keyword">JOIN</span> cla <span class="hljs-keyword">ON</span> grade.cid = cla.id <span class="hljs-keyword">WHERE</span> grade.gre <= %s <span class="hljs-keyword">ORDER</span> <span class="hljs-keyword">BY</span> grade.uid, grade.gre <span class="hljs-keyword">DESC</span> <span class="hljs-number">2016</span>-<span class="hljs-number">05</span>-<span class="hljs-number">10</span> <span class="hljs-number">15</span>:<span class="hljs-number">42</span>:<span class="hljs-number">06</span>,<span class="hljs-number">742</span> INFO sqlalchemy.engine.base.Engine (<span class="hljs-number">70</span>,) [(<span class="hljs-number">2</span>L, <span class="hljs-number">66</span>L, <span class="hljs-string">'yuwen'</span>), (<span class="hljs-number">2</span>L, <span class="hljs-number">50</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">3</span>L, <span class="hljs-number">60</span>L, <span class="hljs-string">'yingyu'</span>), (<span class="hljs-number">5</span>L, <span class="hljs-number">66</span>L, <span class="hljs-string">'yuwen'</span>)] >>> </code>
或
<code class=" hljs r"><span class="hljs-comment">#用SQL语言来查询</span> >>> query = session.execute(<span class="hljs-string">"select uid from grade where cid = (select id fromla where cname='yuwen')"</span>) select uid from grade where cid = (select id from cla where cname=<span class="hljs-string">'yuwen'</span>) <span class="hljs-number">2016</span>-<span class="hljs-number">05</span>-<span class="hljs-number">10</span> <span class="hljs-number">17</span>:<span class="hljs-number">12</span>:<span class="hljs-number">57</span>,<span class="hljs-number">395</span> INFO sqlalchemy.engine.base.Engine () >>> <span class="hljs-keyword">for</span> re <span class="hljs-keyword">in</span> query: <span class="hljs-keyword">...</span> print re.uid <span class="hljs-keyword">...</span> <span class="hljs-number">2</span> <span class="hljs-number">5</span> >>> </code>
<code class=" hljs avrasm"><span class="hljs-preprocessor">#把学好为2成绩为100的学生成绩改为99</span> >>> query5 = session<span class="hljs-preprocessor">.query</span>(Grade) >>> query5<span class="hljs-preprocessor">.filter</span>(Grade<span class="hljs-preprocessor">.uid</span>==<span class="hljs-number">2</span>,Grade<span class="hljs-preprocessor">.gre</span>==<span class="hljs-number">100</span>)<span class="hljs-preprocessor">.update</span>({Grade<span class="hljs-preprocessor">.gre</span>:<span class="hljs-number">99</span>}) <span class="hljs-number">2016</span>-<span class="hljs-number">05</span>-<span class="hljs-number">10</span> <span class="hljs-number">16</span>:<span class="hljs-number">28</span>:<span class="hljs-number">46</span>,<span class="hljs-number">485</span> INFO sqlalchemy<span class="hljs-preprocessor">.engine</span><span class="hljs-preprocessor">.base</span><span class="hljs-preprocessor">.Engine</span> UPDATE grade <span class="hljs-keyword">SET</span> gre=%s WHERE grade<span class="hljs-preprocessor">.uid</span> = %s <span class="hljs-keyword">AND</span> grade<span class="hljs-preprocessor">.gre</span> = %s <span class="hljs-number">2016</span>-<span class="hljs-number">05</span>-<span class="hljs-number">10</span> <span class="hljs-number">16</span>:<span class="hljs-number">28</span>:<span class="hljs-number">46</span>,<span class="hljs-number">486</span> INFO sqlalchemy<span class="hljs-preprocessor">.engine</span><span class="hljs-preprocessor">.base</span><span class="hljs-preprocessor">.Engine</span> (<span class="hljs-number">99</span>, <span class="hljs-number">2</span>, <span class="hljs-number">100</span>) <span class="hljs-number">1</span>L</code>
此时没有提交还没有正在的改变
<code class=" hljs asciidoc"><span class="hljs-header">mysql> select * from grade where gre=100; +----+------+------+------+</span> <span class="hljs-header">| id | uid | cid | gre | +----+------+------+------+</span> <span class="hljs-header">| 15 | 2 | 3 | 100 | +----+------+------+------+</span> 1 row in set (0.00 sec) >>> session.commit() mysql> select * from grade where gre=100; Empty set (0.00 sec) 也可以这样搞 >>> session.query(Grade).filter(Grade.gre==99).update({Grade.gre:50}) </code>
update里面使用的是字典类型
或这样搞
<code class=" hljs asciidoc">#用SQL语句把学语文的成绩都改为110 >>> session.execute("update grade set gre=110 where cid = (select id from cla ere cname=<span class="hljs-emphasis">'yuwen'</span>)") <span class="hljs-code"> update grade set gre=110 where cid = (select id from cla where cname='yuwen')</span> 2016-05-10 17:15:59,383 INFO sqlalchemy.engine.base.Engine () <sqlalchemy.engine.result.ResultProxy object at 0xb5c895cc> <span class="hljs-header">mysql> select * from grade where cid =(select id from cla where cname='yuwen'); +----+------+------+------+</span> <span class="hljs-header">| id | uid | cid | gre | +----+------+------+------+</span> | 2 | 2 | 1 | 66 | <span class="hljs-header">| 3 | 5 | 1 | 66 | +----+------+------+------+</span> 2 rows in set (0.00 sec) #提交后 >>> session.commit() 2016-05-10 17:16:18,223 INFO sqlalchemy.engine.base.Engine COMMIT >>> <span class="hljs-header">mysql> select * from grade where cid =(select id from cla where cname='yuwen'); +----+------+------+------+</span> <span class="hljs-header">| id | uid | cid | gre | +----+------+------+------+</span> | 2 | 2 | 1 | 110 | <span class="hljs-header">| 3 | 5 | 1 | 110 | +----+------+------+------+</span> 2 rows in set (0.00 sec)</code>
<code class=" hljs avrasm"><span class="hljs-preprocessor">#删除成绩为50的成绩记录</span> >>> session<span class="hljs-preprocessor">.query</span>(Grade)<span class="hljs-preprocessor">.filter</span>(Grade<span class="hljs-preprocessor">.gre</span>==<span class="hljs-number">50</span>)<span class="hljs-preprocessor">.delete</span>()</code>
<code class=" hljs asciidoc">#删除选修英语的所有成绩记录,用SQL进行 >>> session.execute( "delete from grade where cid =(select id from cla where cme=<span class="hljs-emphasis">'yingyu'</span>)") 2016-05-10 16:55:55,472 INFO sqlalchemy.engine.base.Engine delete from grade where cid =(select id from cla where cname=<span class="hljs-emphasis">'yingyu'</span>) 2016-05-10 16:55:55,472 INFO sqlalchemy.engine.base.Engine () mysql> select * from grade where cid = (select id from cla where cname=<span class="hljs-emphasis">'yingyu'</span>) <span class="hljs-header"> -> ; +----+------+------+------+</span> <span class="hljs-header">| id | uid | cid | gre | +----+------+------+------+</span> | 5 | 5 | 3 | 96 | | 9 | 4 | 3 | 76 | <span class="hljs-header">| 14 | 3 | 3 | 60 | +----+------+------+------+</span> 3 rows in set (0.00 sec) >>> session.commit() 2016-05-10 16:56:33,075 INFO sqlalchemy.engine.base.Engine COMMIT >>> mysql> select * from grade where cid = (select id from cla where cname=<span class="hljs-emphasis">'yingyu'</span>) <span class="hljs-code"> -> ;</span> Empty set (0.00 sec)</code>
级联删除:在relationship关联时要加上passive_deletes=True外键要加上ondelete=’CASCADE’,否则sqlalchemy不能级联删除
这些是多表连接的操作
单表的操作请看http://blog.csdn.net/u011573853/article/details/51355113
一些细节会在下面进行说明(事务,加锁,编码等)
http://blog.csdn.net/u011573853/article/details/51366124

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Die Hauptaufgabe von MySQL in Webanwendungen besteht darin, Daten zu speichern und zu verwalten. 1.Mysql verarbeitet effizient Benutzerinformationen, Produktkataloge, Transaktionsunterlagen und andere Daten. 2. Durch die SQL -Abfrage können Entwickler Informationen aus der Datenbank extrahieren, um dynamische Inhalte zu generieren. 3.Mysql arbeitet basierend auf dem Client-Server-Modell, um eine akzeptable Abfragegeschwindigkeit sicherzustellen.

Zu den Schritten zum Erstellen einer MySQL -Datenbank gehören: 1. Erstellen einer Datenbank und Tabelle, 2. Daten einfügen, und 3. Durchführen von Abfragen. Verwenden Sie zunächst die Anweisungen für erstellte und creatEtable, um die Datenbank und Tabelle zu erstellen, und verwenden Sie dann die Anweisung InsertInto, um die Daten einzulegen, und verwenden Sie schließlich die Auswahlanweisung, um die Daten abzufragen.

MySQL ist für Anfänger geeignet, da es einfach zu bedienen und leistungsfähig ist. 1.Mysql ist eine relationale Datenbank und verwendet SQL für CRUD -Operationen. 2. Es ist einfach zu installieren und erfordert, dass das Stammbenutzerkennwort konfiguriert wird. 3.. Verwenden Sie Einfügen, Aktualisieren, Löschen und Wählen Sie, um Datenvorgänge auszuführen. 4. OrderBy, wo und Join kann für komplexe Abfragen verwendet werden. 5. Debugging erfordert die Überprüfung der Syntax und verwenden Sie Erklärungen zur Analyse der Abfrage. 6. Die Optimierungsvorschläge umfassen die Verwendung von Indizes, die Auswahl des richtigen Datentyps und der guten Programmiergewohnheiten.


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Damn Vulnerable Web App (DVWA) ist eine PHP/MySQL-Webanwendung, die sehr anfällig ist. Seine Hauptziele bestehen darin, Sicherheitsexperten dabei zu helfen, ihre Fähigkeiten und Tools in einem rechtlichen Umfeld zu testen, Webentwicklern dabei zu helfen, den Prozess der Sicherung von Webanwendungen besser zu verstehen, und Lehrern/Schülern dabei zu helfen, in einer Unterrichtsumgebung Webanwendungen zu lehren/lernen Sicherheit. Das Ziel von DVWA besteht darin, einige der häufigsten Web-Schwachstellen über eine einfache und unkomplizierte Benutzeroberfläche mit unterschiedlichen Schwierigkeitsgraden zu üben. Bitte beachten Sie, dass diese Software