> For the complete documentation index, see [llms.txt](https://doc.telosys.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.telosys.org/target-sql-scripts/predefined-rules.md).

# Predefined rules

Telosys provides predefined rules to generate SQL for the most common databases.

To use them, simply indicate the database type in the template file (.vm).

The target database can be specified using the following directive :

```
#set ( $env.database = 'databaseType' )
```

Since version 4.0 Telosys has the following predefined database types:

* **POSTGRESQL** 
* **MYSQL** 
* **ORACLE** 
* **SQLSERVER** 
* **ANSISQL**  (for standard ANSI-SQL )

The predefined database types are not case sensitive.

Examples:

```
#set ( $env.database = 'postgresql' )
#set ( $env.database = 'PostgreSQL' )
#set ( $env.database = 'POSTGRESQL' )
```

If you try to use an unknown database name, an error will occur.