Expression mapping allows using simple and complex expressions and formulas to transform source data into target field values.
To use expression mapping, first click the Column list and select Expression. Then enter the expression in the box.
Expression mapping uses different syntax depending on whether old or new data integration engine (runtime) is used. You can determine the engine your package uses by selecting the Use new runtime check box on the tab bar.
Old integration runtime uses Microsoft SQL Integration Services expression syntax. You can find the information about it in Microsoft documentation
New integration runtime uses our own expression syntax that is described in Expression Syntax.
You can find more information about main syntax differences in the Main Differences between Old and New Runtime Syntax topic.
If your package uses new runtime, you may not only enter expressions in the box, but also use a helpful expression editor. You may open the expression editor by clicking the button.
Expression editor lists the operators that you can use in the bottom, and all the available source columns and functions on the left. You can click them in order to quickly add them to your expression. You can also click the in order to quickly find the required column or function.
Expression editor provides syntax highlighting and code completion. To use code completion, simply start typing the expression in the Expression editor, and Skyvia will show all the suitable identifiers and functions. For functions, code completion can even display the argument list.
Moreover, Expression Editor automatically validates your expressions while you edit them and underlines errors in them. Whenever needed, you may also manually validate an expression by clicking the Validate button. To view details of the error, simply point the underlined part of your expression, and Expression editor displays information about the error,
Additionally, you may test your expressions with test data even without starting the package. For this, click the Preview button. Then enter test values for the columns, referenced in the expression, to the corresponding boxes in the Value column (you may specify null values by selecting check boxes in the Null column, and view the expression result in the Result column.