Where Clause (Database Source Wizard)
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By default the DataSource will read all the data from the source data table and any linked tables. In a large database this can be huge amounts of data. In order to reduce the data read an SQL WHERE clause can be used which will reduce the quantity of data read.
The 'WHERE SQL' must start with keyword 'WHERE' and MUST use the name 'TableAlias' when referencing columns within the source table.
Failure to use the TableAlias will result in errors (i.e. "WHERE Country = 'USA'" could fail you should use "WHERE TableAlias.Country = 'USA'")
Failure to use the TableAlias will result in errors (i.e. "WHERE Country = 'USA'" could fail you should use "WHERE TableAlias.Country = 'USA'")
The WHERE clause can also be parameterized to allow values to be taken from within the transform.
Once you have completed your WHERE Clause it can be tested with the Test button, the results are shown in dialog.
It is advisable to test the query before exiting the wizard.
If you want to test the query then you need to provide default values for all of the parameters as you define them.
For complex queries it is recommended that you build and test them in your standard database tools, and then cut and paste the SQL into this dialog.
See Also