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====== Database Adaptor ======

{{:TAST-icon.png?nolink&70|}} 

===== Setup =====

In the initialization process the database adapter requests the necessary data to establish the connection with the destination database, and tries to make the connection. If it fails, the process is aborted.

==== Initialization Parameters ====

  * **Host:** Represents the ip address or the machine's dns name where the database resides.
  * **Port:** The port number that listens for incoming connections to the database.
  * **DbName:** Name of the instance or database service.
  * **User:** User name.
  * **Passwd:** User password.
  * **DbType:** Indicates the provider or type of database to which we want to connect.

==== Functions ====

  * **connect_DB():** Tries to connect to the configured database. Returns true if it succeeds or false otherwise.
 
  * **dBExecuteStatement(Statement):** Executes the SQL that it's contain in the statement. Allows the user to modify the data in the destination database. You can write sql statements Insert, Delete, Update and Merge  in the statement parameter. 

  * **dBGetQueryData(Query):** Executes the SQL Select statement contained in the Query parameter, and returns the results as a TastTableData variable to the executor, which allows access and work with the data in later steps of the diagram. The Query parameter contains the Select statement to execute in the database. It is possible to use variables created in the diagram within the Query parameter, the function will substitute the variables for their values at run time.

  * **disconnect_DB():** Tries to disconnect from the database. Returns true if it succeeds or false otherwise.

  * **getNumColumns():** Returns the number of columns contained in the TastTableData that was generated by the execution of the dBGetQueryData function. It requires the execution of the dBGetQueryData function in previous steps of the diagram.

  * **getNumRows():** Returns the number of rows contained in the TastTableData that was generated by the execution of the dBGetQueryData function. It requires the execution of the dBGetQueryData function in previous steps of the diagram. 

  * **getTableValue(RowNum, ColNum):** Returns the value contained in the cell indicated by the parameters Row and Col. It requires the execution of the dBGetQueryData function in previous steps of the diagram. 

  * **tableRecordCount(TableName, WhereClausule):** Performs a SQL query using the SQL Count (*) function. The tableName parameter represents the name of the table or view to be used for the Query, and the whereClausule parameter represents the SQL where  clause that we must apply. Returns the number of rows counted by the sentence.

==== Managing Variables in the database Adaptor ====

The management of variables in the DB Adapter is an important topic, especially it is important how the variables are handled within the predefined function of the query.

  * Instead of supporting parameters, its better to substitute them using this syntax, with Data being the variable to replace, '"+ #Data +"' (single quote, double quotes). For example:

    SELECT '" + #Data + "'    FROM dual   

  * In addition, queries have often used an alias that is enclosed in quotes. For example:

    SELECT domain FROMdual as //"Domain"//

  * If complex queries are manipulated, with several aliases in which you want to substitute several variables, it works by building in a javascript the complete query, being necessary to jump the quotes "" of the aliases with this symbol: \. For example:

    SELECT domain FROM dual S //\ "Domain" \//
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