tELTMysqlMap properties - 6.3

Talend Open Studio for Big Data Components Reference Guide

EnrichVersion
6.3
EnrichProdName
Talend Open Studio for Big Data
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Component family

ELT/Map/Mysql

Basic settings

Use an existing connection

Select this check box and in the Component List click the relevant connection component to reuse the connection details you already defined.

Note

When a Job contains the parent Job and the child Job, if you need to share an existing connection between the two levels, for example, to share the connection created by the parent Job with the child Job, you have to:

  1. In the parent level, register the database connection to be shared in the Basic settings view of the connection component which creates that very database connection.

  2. In the child level, use a dedicated connection component to read that registered database connection.

For an example about how to share a database connection across Job levels, see Talend Studio User Guide.

 

ELT Mysql Map editor

The ELT Map editor allows you to define the output schema as well as build graphically the SQL statement to be executed. The column names of schema can be different from the column names in the database.

 

Style link

Select the way in which links are displayed.

Auto: By default, the links between the input and output schemas and the Web service parameters are in the form of curves.

Bezier curve: Links between the schema and the Web service parameters are in the form of curve.

Line: Links between the schema and the Web service parameters are in the form of straight lines.

This option slightly optimizes performance.

 

Property type

Either Built-in or Repository.

Since version 5.6, both the Built-In mode and the Repository mode are available in any of the Talend solutions.

 

 

Built-in: No property data stored centrally.

 

 

Repository: Select the Repository file where Properties are stored. The following fields are pre-filled in using fetched data.

 

Host

Database server IP address.

 

Port

Listening port number of DB server.

 

Database

Name of the database.

 

Username and Password

DB user authentication data.

To enter the password, click the [...] button next to the password field, and then in the pop-up dialog box enter the password between double quotes and click OK to save the settings.

Dynamic settings

Click the [+] button to add a row in the table and fill the Code field with a context variable to choose your database connection dynamically from multiple connections planned in your Job. This feature is useful when you need to access database tables having the same data structure but in different databases, especially when you are working in an environment where you cannot change your Job settings, for example, when your Job has to be deployed and executed independent of Talend Studio.

The Dynamic settings table is available only when the Use an existing connection check box is selected in the Basic settings view. Once a dynamic parameter is defined, the Component List box in the Basic settings view becomes unusable.

For examples on using dynamic parameters, see Scenario 3: Reading data from MySQL databases through context-based dynamic connections and Scenario: Reading data from different MySQL databases using dynamically loaded connection parameters. For more information on Dynamic settings and context variables, see Talend Studio User Guide.

Global Variables

ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box.

A Flow variable functions during the execution of a component while an After variable functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl + Space to access the variable list and choose the variable to use from it.

For further information about variables, see Talend Studio User Guide.

Usage

tELTMysqlMap is used along with a tELTMysqlInput and tELTMysqlOutput. Note that the Output link to be used with these components must correspond strictly to the syntax of the table name.

Note

The ELT components do not handle actual data flow but only schema information.

Connecting ELT components

The ELT components do not handle any data as such but table schema information that will be used to build the SQL query to execute. Therefore the only connection required to connect these components together is a simple link.

Note that the output name you give to the link when creating it should always be the exact name of the table to be accessed as this parameter will be used in the SQL statement generated.

For the related topic, see Talend Studio User Guide.

Mapping and joining tables

In the ELT Mapper, you can select specific columns from the input schema and include them in the output schema.

  • As you would do it in the regular Map editor, simply drag & drop the columns from the input schema towards the output table defined.

  • Use the Ctrl or Shift key for multiple selection of contiguous or non-contiguous table columns.

You can implement explicit joins to retrieve various data from different tables.

  • Select the Explicit join check box for the relevant column of the input schema and then select a type of join from the join list in the upper right corner of the input schema.

  • Possible joins include: INNER JOIN, LEFT OUTER JOIN, RIGHT OUTER JOIN and CROSS JOIN. By default, the INNER JOIN is selected.

You can also create alias tables to retrieve various data from the same table.

  • In the input area, click the [+] button in the upper left corner of the map editor to create a new alias.

  • Select the table on which the alias is based.

  • Type in a new name for the alias table, preferably not the same as the main table.

Adding where and other clauses

You can also restrict the Select statement based on a Where clause and/or other clauses such as Group By, Order By, etc. by clicking the Add filter row button at the top of the output table in the map editor.

To add a restriction based on a Where clause, click the Add filter row button and select Add a WHERE clause from the pop-up menu.

To add a restriction based on Group By, Order By etc., click the Add filter row button and select Add an other(GROUP...) clause from the pop-up menu.

Make sure that all input components are linked correctly to the ELT Map component to be able to implement all inclusions, joins and clauses.

Generating the SQL statement

The mapping of elements from the input schemas to the output schemas creates instantly the corresponding SELECT statement. The clauses are also included automatically.