tMysqlInput

Executes a DB query with a strictly defined order which must correspond to the
schema definition.

tMysqlInput reads a database and extracts fields based on a query. Then
it passes on the field list to the next component via a Main row link.

Depending on the Talend
product you are using, this component can be used in one, some or all of the following
Job frameworks:

Standard: see tMysqlInput Standard properties.

The component in this framework is available in all Talend
products.
MapReduce: see tMysqlInput MapReduce properties (deprecated).

The component in this framework is available in all subscription-based Talend products with Big Data
and Talend Data Fabric.
Spark Batch: see tMysqlInput properties for Apache Spark Batch.

This component also allows you to connect and read data from a RDS Aurora or a RDS MySQL
database.

The component in this framework is available in all subscription-based Talend products with Big Data
and Talend Data Fabric.

tMysqlInput Standard properties

These properties are used to configure tMysqlInput running in
the Standard Job framework.

The Standard
tMysqlInput component belongs to the Databases family.

The component in this framework is available in all Talend
products.

Note: This component is a specific version of a dynamic database
connector. The properties related to database settings vary depending on your database
type selection. For more information about dynamic database connectors, see Dynamic database components.

Basic settings

Database	Select a type of database from the list and click Apply.
Property type	Either Built-In or Repository. Built-In: No property data stored centrally. Repository: Select the repository file where the properties are stored.
	Click this icon to open a database connection wizard and store the database connection parameters you set in the component Basic settings view. For more information about setting up and storing database connection parameters, see Talend Studio User Guide.
DB version	Select the version of the database to be used.
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: 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. 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.
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.
Schema and Edit Schema	A schema is a row description. It defines the number of fields (columns) to be processed and passed on to the next component. When you create a Spark Job, avoid the reserved word `line` when naming the fields. This component offers the advantage of the dynamic schema feature. This allows you to retrieve unknown columns from source files or to copy batches of columns from a source without mapping each column individually. For further information about dynamic schemas, see Talend Studio User Guide. This dynamic schema feature is designed for the purpose of retrieving unknown columns of a table and is recommended to be used for this purpose only; it is not recommended for the use of creating tables.
	Built-In: You create and store the schema locally for this component only.
	Repository: You have already created the schema and stored it in the Repository. You can reuse it in various projects and Job designs.
	Click Edit schema to make changes to the schema. If the current schema is of the Repository type, three options are available: View schema: choose this option to view the schema only. Change to built-in property: choose this option to change the schema to Built-in for local changes. Update repository connection: choose this option to change the schema stored in the repository and decide whether to propagate the changes to all the Jobs upon completion. If you just want to propagate the changes to the current Job, you can select No upon completion and choose this schema metadata again in the Repository Content window.
Table Name	Name of the table to be read.
Query type and Query	Enter your DB query paying particularly attention to properly sequence the fields in order to match the schema definition. If using the dynamic schema feature, the SELECT query must include the * wildcard, to retrieve all of the columns from the table selected.
Specify a data source alias	Select this check box and specify the alias of a data source created on the Talend Runtime side to use the shared connection pool defined in the data source configuration. This option works only when you deploy and run your Job in Talend Runtime . Warning: If you use the component’s own DB configuration, your data source connection will be closed at the end of the component. To prevent this from happening, use a shared DB connection with the data source alias specified. This check box is not available when the Use an existing connection check box is selected.

Advanced settings

Additional JDBC parameters	Specify additional connection properties for the DB connection you are creating. This option is not available if you have selected the Use an existing connection check box in the Basic settings. Note: When you need to handle data of the time-stamp type 0000-00-00 00:00:00 using this component, set the parameter as: `noDatetimeStringSync=true&zeroDateTimeBehavior=convertToNull`.
Enable stream	Select this check box to enables streaming over buffering which allows the code to read from a large table without consuming a large amount of memory in order to optimize the performance. This check box is available only when `Mysql 4` or `Mysql 5` is selected from the DB Version drop-down list.
Trim all the String/Char columns	Select this check box to remove leading and trailing whitespace from all the String/Char columns.
Trim column	Remove leading and trailing whitespace from defined columns. Note: Clear Trim all the String/Char columns to enable Trim columns in this field.
tStatCatcher Statistics	Select this check box to collect log data at the component level.

Global Variables

Global Variables	NB_LINE: the number of rows processed. This is an After variable and it returns an integer. QUERY: the query statement being processed. This is a Flow variable and it returns a string. 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.

NB_LINE: the number of rows processed. This is an After
variable and it returns an integer.

QUERY: the query statement being processed. This is a Flow
variable and it returns a string.

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

Usage rule	This component covers all possible SQL queries for Mysql databases.
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 Reading data from databases through context-based dynamic connections and 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.

Usage rule

This component covers all possible SQL queries for Mysql
databases.

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 Reading data from databases through context-based dynamic connections and 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.

Writing columns from a MySQL database to an output file using
tMysqlInput

In this scenario we will read certain columns from a MySQL database, and then
write them to a table in a local output file.

Dragging and dropping components and linking them together

Drop tMysqlInput and tFileOutputDelimited from the Palette onto the workspace.
Link tMysqlInput to tFileOutputDelimited using a Row > Main connection.

Configuring the components

Double-click tMysqlInput to open its
Basic Settings view in the Component tab.
From the Property Type list, select
Repository if you have already stored
the connection to database in the Metadata
node of the Repository tree view. The
property fields that follow are automatically filled in.

For more information about how to store a database connection, see

Talend Studio

User Guide.

If you have not defined the database connection locally in the Repository, fill in the details manually after
selecting Built-in from the Property Type list.
Set the Schema as Built-in and click Edit
schema to define the desired schema.

The schema editor opens:
Click the [+] button to add the rows
that you will use to define the schema, four columns in this example
id, first_name,
city and salary.

Under Column, click in the fields to
enter the corresponding column names.

Click the field under Type to define the
type of data.

Click OK to close the schema
editor.
Next to the Table Name field, click
the […] button to select the database
table of interest.

A dialog box displays a tree diagram of all the tables in the selected
database:
Click the table of interest and then click OK to close the dialog box.
Set the Query Type as Built-In.
In the Query box, enter the query
required to retrieve the desired columns from the table.
Double-click tFileOutputDelimited to set
its Basic settings in the Component tab.
Next to the File Name field, click the
[…] button to browse your directory
to where you want to save the output file, then enter a name for the
file.

Select the Include Header check box to
retrieve the column names as well as the data.
Save the Job.

Executing the Job

The results below can be found after F6 is
pressed to run the Job.

As shown above, the output file is written with the desired column names and
corresponding data, retrieved from the database:

Note:

The Job can also be run in the Traces Debug
mode, which allows you to view the rows as they are being written to the output
file, in the workspace.

Using context parameters when reading a table from a database

In this scenario, MySQL is used for demonstration purposes. We will read a
table from a MySQL database, using a context parameter to refer to the table name.

Dragging and dropping components and linking them together

Drop tMysqlInput and tLogRow from the Palette onto the workspace.
Link tMysqlInput to tLogRow using a Row >
Main connection.

Configuring the components

Double-click tMysqlInput to open its
Basic Settings view in the Component tab.
From the Property Type list, select
Repository if you have already stored
the connection to database in the Metadata
node of the Repository tree view. The
property fields that follow are automatically filled in.

For more information about how to store a database connection, see

Talend Studio

User Guide.

If you have not defined the database connection in the Repository, fill in the details manually after
selecting Built-in from the Property Type list.
Set the Schema as Built-In and click Edit
schema to define the desired schema.

The schema editor opens:
Click the [+] button to add the rows
that you will use to define the schema, seven columns in this example:
id, first_name, last_name, city, state, date_of_birth and salary.

Under Column, click the fields to enter
the corresponding column names.

Click the fields under Type to define
the type of data.

Click OK to close the schema
editor.
Put the cursor in the Table Name field
and press F5 for context parameter setting.

For more information about context settings, see
Talend Studio

User Guide.
Keep the default setting in the Name
field and type in the name of the database table in the Default value field, employees in this case.
Click Finish to validate the setting.

The context parameter context.TABLE
automatically appears in the Table Name
field.

In the Query type list, select Built-In. Then, click Guess
Query to get the query statement.

In this use case, we want to read the records with the salary above 8000.
Therefore, we add a Where clause and the final query statement
is as follows:

"SELECT
  "+context.TABLE+".`id`,
  "+context.TABLE+".`first_name`,
  "+context.TABLE+".`last_name`,
  "+context.TABLE+".`city`,
  "+context.TABLE+".`state`,
  "+context.TABLE+".`date_of_birth`,
  "+context.TABLE+".`salary`
FROM "+context.TABLE+"
WHERE
  "+context.TABLE+".`salary` &gt; 8000"

"SELECT

"+context.TABLE+".`id`,

"+context.TABLE+".`first_name`,

"+context.TABLE+".`last_name`,

"+context.TABLE+".`city`,

"+context.TABLE+".`state`,

"+context.TABLE+".`date_of_birth`,

"+context.TABLE+".`salary`

FROM "+context.TABLE+"

WHERE

"+context.TABLE+".`salary` > 8000"

Double-click tLogRow to set its Basic Settings in the Component tab.
In the Mode area, select Table (print values in cells of a table) for a
better display of the results.
Save the Job.

Executing the Job

The results below can be found after F6 is
pressed to run the Job.

As shown above, the records with the salary greater than 8000 are
retrieved.

Reading data from databases through context-based dynamic
connections

In this scenario, MySQL is used for demonstration purposes. We will read data
from database tables with the same data structure but in two different MySQL databases named
project_q1 and project_q2 respectively. We will
specify the connections to these databases dynamically at runtime, without making any
modification to the Job.

Dropping and linking the components

Drop two tMysqlConnection, a tMysqlInput, a tLogRow, and a tMysqlClose
components onto the design workspace.
Link the first tMysqlConnection to the
second tMysqlConnection and the second
tMysqlConnection to tMysqlInput using Trigger > On Subjob Ok
connections.
Link tMysqlInput to tLogRow using a Row >
Main connection.
Link tMysqlInput to tMysqlClose using a Trigger
> On Subjob Ok connection.

Creating a context variable

To be able to choose a database connection dynamically at runtime, we need to
define a context variable, which will then be configure it in the Dynamic settings of the database input component.

In the Contexts view, click the [+] button to add a row in the table, click in
the Name field and enter a name for the
variable, myConnection in this
example.
From the Type list field, select
List Of Value.
Click in the Value field and then click
the button that appears in the field to open the Configure value of list dialog box.
In the Configure value of list dialog
box, click the New… button to open the
New Value dialog box, and enter the
name of one of the connection components in the text field, tMysqlConnection_1 in this example. Then click
OK to close the dialog box.

Repeat this step to specify the other connection component name as another
list item, tMysqlConnection_2 in this
example.

When done, click OK to close the
Configure Values dialog box.
Select the check box next to the variable value field, and fill the
Prompt field with the message you want
to display at runtime, Select a connection
component: in this example.

Configuring the components

Double-click the first tMysqlConnection
component to show its Basic settings view,
and set the connection details. For more information on the configuration of
tMysqlConnection, see tMysqlConnection.

Note that we use this component to open a connection to a MySQL databased
named project_q1.
Configure the second tMysqlConnection
component in the same way, but fill the Database field with project_q2 because we want to use this component to open a
connection to another MySQL database, project_q2.
Double-click the tMysqlInput component to
show its Basic settings view.
Select the Use an existing connection
check box, and leave the Component List box
as it is.
Click the […] button next to Edit schema to open the Schema dialog box and define the data structure of the
database table to read data from.

In this example, the database table structure is made of four columns,
id (type Integer, 2 characters long),
firstName (type String, 15 characters
long), lastName (type String, 15
characters long), and city (type String,
15 characters long). When done, click OK to
close the dialog box and propagate the schema settings to the next
component.
Fill the Table field with the database
table name, customers in this example,
and click Guess Query to generate the query
statement corresponding to your table schema in the Query field.
In the Dynamic settings view, click the
[+] button to add a row in the table,
and fill the Code field with the code
script of the context variable you just created, " + context.myConnection + " in this example.
In the Basic settings view of the
tLogRow component, select the Table option for better display effect of the Job
execution result.
In the Dynamic settings view of the
tMysqlClose component, do exactly the
same as in the Dynamic settings view of the
tMysqlInput component.

Saving and executing the Job

Press Ctrl+S to save your Job and press
F6 or click Run to launch it.

A dialog box appears prompting you to specify the connection component you
want to use.
Select the connection component, tMysqlConnection_1, and click OK.

The data read from database project_q1
is displayed in the Run console.
Press F6 or click Run
to launch your Job again. When prompted, select the other connection
component, tMysqlConnection_2, to read data
from the other database, project_q2.

The data read from database project_q2
is displayed in the Run console.

Writing dynamic columns from a database to an output file

This scenario applies only to subscription-based Talend products.

In this scenario, MySQL is used for demonstration purposes. You will read
dynamic columns from a MySQL database, map them and then write them to a table in a local
output file. By defining a dynamic column alongside known column names, we can retrieve all of
the columns from the database table, including the unknown columns.

Dragging and dropping components and linking them together

Drop a tMysqlInput, a tMap and a tFileOutputDelimited component onto the workspace.
Link tMysqlInput to tMap using a Row >
Main connection.
Link tMap to tFileOutputDelimited using a Row >
*New Output* (Main) connection.

Configuring the components

Configuring the tMysqlInput component

Double-click tMysqlInput
to open its Basic Settings view in the
Component tab.

Warning:

The dynamic schema feature is only supported in
Built-In mode.
Select Built-in as the
Property Type.
Select the DB Version from the corresponding list.
Next to Host, enter the database server IP
address.
Next to Port, enter the listening port number of the
database server.
Enter your authentication data in the Username and
Password fields.
Set the Schema type
as Built-in and click Edit schema to define the dynamic schema.

The schema editor opens:
Click the [+] button to
add a row to the schema.
1. Under Column and Db
  Column, click in the fields to enter the corresponding
  column names.
2. Click the field under Type to define the type of
  data.
3. Click the arrow and select Dynamic from the
  list.
  
  Warning:
  
  Under Type, the dynamic column type
  must be set as Dynamic.
Click OK to close the
schema editor.
Next to the Table Name
field, click the […] button to select
the database table of interest.

A dialog box displays a tree diagram of all the tables in the selected
database:
Click the table of interest and then click OK to close
the dialog box.
Set the Query Type as
Built-In.
In the Query box, enter the query required to retrieve
all of the columns from the table.

Warning:

In the SELECT statement it is necessary to use the
* wildcard character, to retrieve all of the
columns from the selected table.

Configuring the tMap component

Click tMap to open its
Basic Settings view in the Component tab.
Click […] next to
Map Editor to map the column from the
source file.
Drop the column defined as dynamic from the input schema on
the left onto the output schema on the right.

The column dropped on the output schema retains its original
values.

Warning:

The dynamic column must be mapped on
a one to one basis and cannot undergo any transformations. It cannot be
used in a filter expression or in a variables section. It cannot be
renamed in the output table and cannot be used as a join condition.
Click OK to close the
Map Editor.

Configuring the tFileOutputDelimited component

Double-click tFileOutputDelimited to set
its Basic Settings in the Component tab.
Next to the File Name field, click the
[…] button to browse your directory
to where you want to save the output file, then enter a name for the
file.
Select the Include Header check box to
retrieve the column names as well as the data.

Executing the Job

Press Ctrl+S to save the
Job.
Press F6 to run
it.

The output file is written with all the column names and corresponding data,
retrieved from the database via the dynamic schema:

Note:

The Job can also be run in the Traces
Debug mode, which allows you to view the rows as they are written to
the output file, in the workspace.

For further information about defining and mapping dynamic schemas,
see
Talend Studio

User Guide.

Related scenarios

For related scenarios, see: