# tELTMap

Uses the tables provided as input to feed the parameter in the built SQL statement. The statement can include inner or outer joins to be implemented between tables or between one table and its aliases.

Information noteWarning: The query order of the built SQL statement is generated the same way as it appears in the GUI, so having the LEFT JOIN clauses prior to the INNER JOIN clauses could result in data loss. However, Talend has no plan to change this behavior from the GUI at this time, as some databases like [PostgreSQL](https://www.postgresql.org/docs/12/explicit-joins.html) consider the query order when generating the execution plan and the order part is necessary for query runtime optimization.

The three ELT components are closely related, in terms of their operating conditions. These components should be used to handle DB schemas to generate Insert statements, including clauses, which are to be executed in the DB output table defined.

For more technologies supported by Talend, see [Talend components](https://help.qlik.com/talend/r/en-US/7.3/components/elt-jdbc).

Note that it is highly recommended to use the ELT components for a specific type of database (if any) instead of the ELT components. For example, for Teradata, it is recommended to use the tELTTeradataInput, tELTTeradataMap and tELTTeradataOutput components instead.

### In this section

* [tELTMap Standard properties](https://help.qlik.com/talend/en-US/components/7.3/elt-jdbc/teltmap-standard-properties)

**Related concepts**

[Aggregating Snowflake data using context variables as table and connection names](https://help.qlik.com/talend/en-US/components/7.3/elt-jdbc/teltinput-teltmap-tsnowflakeinput-tlogrow-aggregating-snowflake-data-using-context-variables-as-table-and-connection-names "This scenario shows you an example of aggregating Snowflake data from two source tables STUDENT and TEACHER to one target table FULLINFO using the ELT components. In this example, set all input and output table names and connection names to context variables.")