title: Why did I get error in TypeOrm with JoinAndSelect?
body: <p>I have entities in NestJS app:</p>
  <pre><code>@Entity({ name: 'SYSTEM' })
  export class System {
    @PrimaryColumn()
    ID: number;
  
    @Column()
    NAME: string;
  
    @OneToMany(() =&gt; Section, (section) =&gt; section.system)
    sections: Section[];
  }
  
  @Entity({ name: 'SECTION' })
  export class Section {
    @PrimaryColumn()
    ID: number;  
  
    @Column()
    SYSTEM_ID: number;  
  
    @ManyToOne(() =&gt; System, (system) =&gt; system.sections)
    system: System;
  }
  </code></pre>
  <p>And try to complete LeftJoin &amp; Select. I use TypeOrm for this purpose:</p>
  <pre><code>return await this.systemRepository
    .createQueryBuilder('system')
    .leftJoinAndSelect('system.sections', 'section')          
    .getMany();
  </code></pre>
  <p><strong>What am I doing wrong?</strong> The result is:</p>
  <blockquote>
  <p>&quot;originalError&quot;: {
  &quot;info&quot;: {
  &quot;name&quot;: &quot;ERROR&quot;,
  &quot;event&quot;: &quot;errorMessage&quot;,
  &quot;number&quot;: 207,
  &quot;state&quot;: 1,
  &quot;class&quot;: 16,
  &quot;message&quot;: &quot;Invalid column name 'systemID'.&quot;,
  &quot;serverName&quot;: &quot;PROTECT&quot;,
  &quot;procName&quot;: &quot;&quot;,
  &quot;lineNumber&quot;: 1
  }
  }</p>
  </blockquote>