Implicit conversion Vs Explicit conversionĮach pair of SSIS data types has its own case, you can find a pair that can be converted implicitly and another one that needs an explicit conversion. In this article, I will not describe the Derived Column Transformation, since it was explained in a previous article in this series: SSIS Derived Column with multiple expression Vs multiple transformation In SSIS, Explicit conversion can be done using different methods, for example: SELECT CAST ( AS Varchar ( 50 ) ) FROM Table For example, when a string is compared to an int, the string is implicitly converted to int before the comparison proceeds: Data types are automatically converted from one data type to another. Implicit conversions are not visible to the user.
In this section, I will try to make a quick overview of each type. There are two types of data type conversion: On the other hand, these data types have some limitations such as the minimum and maximum allowed values for the decimal data type, more detailed can be found at: The SSIS data types were founded to provide a unified set of data types that can handle different types from different sources. Working with Data Types in the Data Flow.For more information, you can refer to the following links:
Microsoft provided very detailed information about SSIS data types and related data types on the different data sources. As an example, string data types are converted into DT_STR, DT_WSTR, DT_TEXT, DT_NTEXT data types.
When handling data using Integration Services Data Flow Task, the source data types are converted into SSIS data types. This article is the seventh article in the SSIS feature face-to-face series, which aims to remove confusion and to illustrate some of the differences between similar features provided by SQL Server Integration Services. In this article, I will first give an overview of SSIS data types and data types conversion methods and then I will illustrate the difference between changing the columns data types from the Source Advanced editor and using Data Conversion Transformation.
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