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POTrouble with SQL Statment
 

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  1. POTrouble with SQL Statment
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    <p>I have a database for a Train company. I want to combine two queries together so I can use them as one from a Java front end.</p> <p>The first query returns the IDs of trains that are not full.</p> <pre><code>select TrainID from Train where Capacity &gt; 0; </code></pre> <p>Each train has a capacity of 50 and I subtract one each time a seat is booked, so if the capacity is greater than zero, then there's a seat on board.</p> <p>The second query returns the RouteID of a train given a destination and origin:</p> <pre><code>select * from Timetable where RouteID = (select RouteID from Routes where OriginID = "New York" and DestinationID = "LA"); </code></pre> <h2>The Question/Need</h2> <p>I want to merge these two queries together so I can have something like:</p> <pre><code>Give me all the Timetable entries for this route ONLY IF there's room on the train. </code></pre> <p>I'm not a DB kinda guy so I'm just having trouble putting two and two together.</p> <p>Edit: Schema is outlined below. Thanks for the answers so far, I'm going to try them now.</p> <p>Routes</p> <pre><code>+---------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------------+-------------+------+-----+---------+-------+ | RouteID | varchar(25) | NO | PRI | NULL | | | OriginID | varchar(25) | NO | MUL | NULL | | | DestinationID | varchar(25) | NO | MUL | NULL | | | Duration | int(3) | NO | | NULL | | +---------------+-------------+------+-----+---------+-------+ </code></pre> <p>Stations</p> <pre><code>+-----------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+-------------+------+-----+---------+-------+ | StationID | varchar(25) | NO | | NULL | | +-----------+-------------+------+-----+---------+-------+ </code></pre> <p>Timetable</p> <pre><code>+-------------+-------------+------+-----+---------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------------+-------------+------+-----+---------------------+----------------+ | TimeID | int(11) | NO | PRI | NULL | auto_increment | | RouteID | varchar(11) | NO | | NULL | | | TrainID | varchar(11) | NO | | NULL | | | DepartDate | timestamp | NO | | 0000-00-00 00:00:00 | | | ArrivalDate | timestamp | NO | | 0000-00-00 00:00:00 | | +-------------+-------------+------+-----+---------------------+----------------+ </code></pre> <p>Train</p> <pre><code>]+----------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +----------+-------------+------+-----+---------+-------+ | TrainID | varchar(11) | NO | PRI | NULL | | | Capacity | int(11) | NO | | 50 | | +----------+-------------+------+-----+---------+-------+ </code></pre>
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    1. COCan you provide the schema for the Train and Timetable tables?
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      1. USJonathanK
    2. COI think we need to know the schema of the two tables in question. I'm not sure which fields are in which tables...
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      1. USFrank V
    3. COWhat database are you using?
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      1. USOMG Ponies
 

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