SSIS Interview: Data Conversion and Derived Column

The Data Conversion Transform performs a similar function to the CONVERT or CAST

Functions In TSQL. The transform is configured in the Data Conversion Transformation Editor,

where you would check each column that you wished to convert and then assign what you

wish to convert it to under the Data Type column.

The Output Alias is the column name you want to assign to the column after it is transformed.

If you don ’ t assign it a new name, it will show as Data Conversion: ColumnName later in the

Data Flow.

The Derived Column Transform creates a new column that is derived from the output

Another column. It is one of the most important transforms in your Data Flow arsenal. You may

wish to use this transformation, for example, to multiply the quantity of orders by the cost of

the order to derive the total cost of the order. You can also use it to find out

the current date or to fill in the blanks in the data by using the ISNULL function. This is one of

the top five transforms that you ’ ll find yourself using to alleviate the need for TSQL scripting in

the package. To configure this transform, drag the column or variable into the Expression

column .Then add any functions to it. A list of functions can be found in the top - right corner of

the Derive Column Transformation Editor. You must then specify, in the Derived Column drop

down box, if you want the output to replace an existing column in the Data Flow or to create a

new column.

 

 

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