<< Click to Display Table of Contents >> ETL > 14.0 > Implementation Guide > Tutorial and implementation guide > Steps > Mapping  Using fixed values

You can use an automatically generated, non-static value for a column. Currently there are 4 types of auto-columns supported:

•Guid
Random UUID (globally unique)

•Number
Autoincremented number (locally unique)

•DateTime
Date and time (not guaranteed to be unique, neither globally nor locally)

•Date
Current date (without time part)

•Time
Current time

•TableName
The name of the source table (not unique). This type of auto-column makes sense in case when two or more tables are selected by a single map statement, and the information about the source table name is important.

To define auto-column, an object notation in the following format is required:

{

    "columns": {

        "target_column_name": 

        {

            "auto": "<type>"

        },
        [...]            

    }

}

 
Where <type> is one of the supported value: Guid, Number, DateTime or TableName. There are no more properties required or defined by auto-columns.

 

Example

Given the following table SourceTable:

 
And the following JSON step definition:

    {

      "id": 1,

      "type": "map",

      "name": "Example of auto-columns",

      "source": "SourceTable",

      "columns": {

        "Name": "Name",

        "Auto_DateTime": { "auto": "datetime" },

        "Auto_Guid": { "auto": "guid" },

        "Auto_Number": { "auto": "number" },

        "Auto_TableName": { "auto": "tableName" }

      },

      "target": "TargetTable_AutoColumns"

    }

 

The following result table TargetTable_AutoColumns is expected:

 

Arbitrary types, casting and converting

Using the type property lets you define a custom cast or custom type length. This common property is available for all column types, see more information in chapter Arbitrary column types.