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====== Data Structure (Data Definition) ======


===== About =====
A ''data structure'' defines the structure of a [[resource|data resource]].

This definition may be created:
  * via a [[data-definition|data definition file]]
  * via a command (Example: for a [[docs:system:database:database|database]], a ''SQL'' statement known as the [[:docs:resource:sql_ddl|Data Definition Language (DDL)]])
  * via the structure of another [[resource|data resource]]




===== Operation =====

==== Creation ====
The creation of a data structure in ''Tabulify'' is done via:
  * the [[docs:op:create|create operation]]
  * [[:docs:resource:sql_ddl|DDL statements]]
  * or during any [[:docs:op:transfer|transfer]] if the [[:docs:flow:target|target]] does not exist

==== View ====
The data structure is viewable via the [[docs:tabul:data:describe|describe operation]]

===== Logical Structure =====

There is roughly three logical structures in the world that are:
  * a [[tabular|tabular]]
  * a ''graph''
  * a ''hierarchy'' (ie a graph without cycle)