FAQ and Composite Key renaming
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@ -172,15 +172,15 @@ What is DQL?
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DQL stands for Doctrine Query Language, a query language that very much looks like SQL
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but has some important benefits when using Doctrine:
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* It uses class names and fields instead of tables and columns, separating concerns between backend and your object model.
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* It utilizes the metadata defined to offer a range of shortcuts when writing. For example you do not have to specify the ON clause of joins, since Doctrine already knows about them.
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* It adds some functionality that is related to object management and transforms them into SQL.
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- It uses class names and fields instead of tables and columns, separating concerns between backend and your object model.
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- It utilizes the metadata defined to offer a range of shortcuts when writing. For example you do not have to specify the ON clause of joins, since Doctrine already knows about them.
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- It adds some functionality that is related to object management and transforms them into SQL.
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It also has some drawbacks of course:
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* The syntax is slightly different to SQL so you have to learn and remember the differences.
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* To be vendor independent it can only implement a subset of all the existing SQL dialects. Vendor specific functionality and optimizations cannot be used through DQL unless implemented by you explicitly.
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* For some DQL constructs subselects are used which are known to be slow in MySQL.
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- The syntax is slightly different to SQL so you have to learn and remember the differences.
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- To be vendor independent it can only implement a subset of all the existing SQL dialects. Vendor specific functionality and optimizations cannot be used through DQL unless implemented by you explicitly.
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- For some DQL constructs subselects are used which are known to be slow in MySQL.
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Can I sort by a function (for example ORDER BY RAND()) in DQL?
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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@ -1,5 +1,5 @@
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Composite Primary Keys
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======================
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Composite and Foreign Keys as Primary Key
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=========================================
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Doctrine 2 supports composite primary keys natively. Composite keys are a very powerful relational database concept
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and we took good care to make sure Doctrine 2 supports as many of the composite primary key use-cases.
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