title: Using multiple conditions in SQL WHERE clause
body: <p>I have been searching online and even amongst Stackoverflow questions about this issue but couldnt receive any related response. 
  The SQL query that I have shown below,</p>
  
  <pre><code>SELECT Scania.GensetType
      , Scania.EngineType
      , Scania.Engine60Hz
      , Scania.Alternator
      , Scania.PriceEur 
  FROM Scania 
  LEFT JOIN NordhavnGenset 
      ON Scania.GensetType=NordhavnGenset.Alternator 
  WHERE (NordhavnGenset.MaxKva='46') 
      and (Generator.Alternator='ECP34-1LN/4') 
      and (insulation.Insulation='F (90ºC/45ºC)') 
      and (Klasse.Klasse='KRS\r') 
      and (airinletfilter.AirInletFilter='No') 
      and (Ip.IP='IP23');
  </code></pre>
  
  <p>Always returns the error message below, and I have checked several times that this column exists in the table!</p>
  
  <pre><code>#1054 - Unknown column 'Generator.Alternator' in 'where clause'
  </code></pre>
  
  <p>However if I execute the query by stopping at the first Where clause, then the results are displayed,</p>
  
  <pre><code>SELECT Scania.GensetType
      , Scania.EngineType
      , Scania.Engine60Hz
      , Scania.Alternator
      , Scania.PriceEur 
  FROM Scania 
  LEFT JOIN NordhavnGenset 
      ON Scania.GensetType=NordhavnGenset.Alternator 
  WHERE (NordhavnGenset.MaxKva='46');
  </code></pre>
  
  <p>The new query</p>
  
  <pre><code>    SELECT  Scania.GensetType, Scania.EngineType, Scania.Engine60Hz, Scania.Alternator, Scania.PriceEur
  FROM Scania  
  LEFT JOIN NordhavnGenset
      ON Scania.GensetType=NordhavnGenset.Alternator 
  LEFT JOIN Generator
      ON Scania.Alternator=Generator.Alternator
  LEFT JOIN Insulation 
      ON NordhavnGenset.Insulation=Insulation.Insulation
  LEFT JOIN Klasse
      ON NordhavnGenset.Class=Klasse.Class
  LEFT JOIN AirInletFilter
      ON NordhavnGenset.AirInletFilter=AirInletFilter.AirInletFilter
  LEFT JOIN IP
      ON NordhavnGenset.Ip=IP.IP
  WHERE (NordhavnGenset.MaxKva='46') and (Generator.Alternator='ECP34-1LN/4') and (Insulation.Insulation='F (90ºC/45ºC)') and (Klasse.Klasse='KRS\r') and (AirInletFilter.AirInletFilter='No') and (IP.IP='IP23');
  </code></pre>