title: Get minimum column value from related entity
body: <p>Please, help me. I cant find information about how do this.
  I have got this code. It load all products with all relations. One of relations is product item. In product item entity I have got price column.</p>
  <p>How I can get minimal product item price without get in my response array of product items?</p>
  <pre><code>const { skip, take } = pagination;
  
      const query = this.createQueryBuilder('product');
  
      query.where('product.shop = :id AND product.blocked = FALSE', {
        id: shop.id,
      });
  
      if (skip) {
        query.offset(Number(skip));
      }
  
      if (take) {
        query.limit(Number(take));
      }
  
      query.leftJoin('product.info', 'info');
      query.leftJoin('product.avatar', 'avatar');
  
      // load product items
      query.leftJoin('product.productItem', 'item');
  
      query.select([
        'product.id',
        'product.path',
        'info.name',
        'info.description',
        'info.info',
        'info.lang',
        'avatar.path',
        'avatar.type',
  
        'item.price'
      ]);
  
      const [list, amount] = await query.getManyAndCount();
  </code></pre>
  <p>Now i have got:</p>
  <pre><code>{
      &quot;list&quot;: [
          {
              &quot;id&quot;: 3,
              &quot;path&quot;: &quot;admin-product-2&quot;,
              &quot;order&quot;: 1,
              &quot;shop&quot;: {
                  &quot;id&quot;: 1
              },
              &quot;info&quot;: [
                  {
                      &quot;name&quot;: &quot;Admin Name ;)&quot;,
                      &quot;description&quot;: &quot;Shorty&quot;,
                      &quot;info&quot;: &quot;&quot;,
                      &quot;lang&quot;: &quot;RU&quot;
                  }
              ],
              &quot;avatar&quot;: null,
              &quot;productItem&quot;: [
                  {
                      &quot;price&quot;: 1000
                  },
                  {
                      &quot;price&quot;: 500
                  },
                  {
                      &quot;price&quot;: 300
                  },
                  {
                      &quot;price&quot;: 2000
                  },
                  {
                      &quot;price&quot;: 3000
                  }
              ]
          }
      ]
  }
  ........
  </code></pre>
  <p>But I need:</p>
  <pre><code>
  {
      &quot;list&quot;: [
          {
              &quot;id&quot;: 3,
              &quot;path&quot;: &quot;admin-product-2&quot;,
              &quot;order&quot;: 1,
              &quot;shop&quot;: {
                  &quot;id&quot;: 1
              },
              &quot;info&quot;: [
                  {
                      &quot;name&quot;: &quot;Admin Name ;)&quot;,
                      &quot;description&quot;: &quot;Shorty&quot;,
                      &quot;info&quot;: &quot;&quot;,
                      &quot;lang&quot;: &quot;RU&quot;
                  }
              ],
              &quot;avatar&quot;: null,
              &quot;minProductItemPrice&quot;: 300
          }
      ]
  }
  
  </code></pre>
  <p>Pls help me</p>