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POHow to solve code duplication in the following PostgreSQL query?
 

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  1. POHow to solve code duplication in the following PostgreSQL query?
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    <p>I have a table Inputs and a derived table Parameters</p> <pre><code>CREATE TABLE Configurables ( id SERIAL PRIMARY KEY ); CREATE TABLE Inputs ( configurable integer REFERENCES Configurables( id ), name text, time timestamp, PRIMARY KEY( configurable, name, time ) ); CREATE TABLE Parameters ( configurable integer, name text, time timestamp, value text, FOREIGN KEY( configurable, name, time ) REFERENCES Inputs( configurable, name, time ) ); </code></pre> <p>The following query checks whether a parameter has been changed, or is not present yet, and inserts the parameter with a new value.</p> <pre><code>QString PostgreSQLQueryEngine::saveParameter( int configurable, const QString&amp; name, const QString&amp; value ) { return QString( "\ INSERT INTO Inputs( configurable, name, time ) \ WITH MyParameter AS \ ( \ SELECT configurable, name, time, value \ FROM \ ( \ SELECT configurable, name, time, value \ FROM Parameters \ WHERE (configurable = %1) AND (name = '%2') AND time = \ ( \ SELECT max( time ) \ FROM Parameters \ WHERE (configurable = %1) AND (name = '%2') \ ) \ UNION \ SELECT %1 AS configurable, '%2' AS name, '-infinity' AS time, NULL AS value \ )AS foo \ ) \ SELECT %1 AS configurable, '%2' AS name, 'now' AS time FROM MyParameter \ WHERE time = (SELECT max(time) FROM MyParameter) AND (value &lt;&gt; '%3' OR value IS NULL); \ \ INSERT INTO Parameters( configurable, name, time, value ) \ WITH MyParameter AS \ ( \ SELECT configurable, name, time, value \ FROM \ ( \ SELECT configurable, name, time, value \ FROM Parameters \ WHERE (configurable = %1) AND (name = '%2') AND time = \ ( \ SELECT max( time ) \ FROM Parameters \ WHERE (configurable = %1) AND (name = '%2') \ ) \ UNION \ SELECT %1 AS configurable, '%2' AS name, '-infinity' AS time, NULL AS value \ )AS foo \ ) \ SELECT %1 AS configurable, '%2' AS name, 'now' AS time, '%3' AS value FROM MyParameter \ WHERE time = (SELECT max(time) FROM MyParameter) AND (value &lt;&gt; '%3' OR value IS NULL); \ " ).arg( configurable ).arg( name ).arg( value ); } </code></pre> <p>How should I best solve the duplication of 2 the MyParameter subqueries?</p> <p>Any other tips on cleaning up a query like this</p>
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    1. COAre you inserting the same configurable, name and time in both tables. You already have a foreign key in Parameters which refers to Inputs. Do you really need de-normalization ?
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      1. POHow to solve code duplication in the following PostgreSQL query?
      1. USEric Fortin
    2. COAdded Configurable definition. A Configurable has a list of inputs, an input can be a Parameter. I chose de-normalizing it so I can easily get an overview from the Inputs table. (there's more tables deriving from Inputs then Parameters)
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      1. POHow to solve code duplication in the following PostgreSQL query?
      1. USPieter
 

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