For relational sources, the Integration Service generates a query for each Source Qualifier transformation when it runs a session. The default query is a SELECT statement for each source column used in the mapping. In other words, the Integration Service reads only the columns that are connected to another transformation.

The following figure shows a single source definition connected to a Source Qualifier transformation, with many source definition columns but only three connected to the final transformation:

Although there are many columns in the source definition, only three columns are connected to another transformation. In this case, the Integration Service generates a default query that selects only those three columns:

If any table name or column name contains a database reserved word, you can create and maintain a file, reswords.txt, containing reserved words. When the Integration Service initializes a session, it searches for reswords.txt in the Integration Service installation directory. If the file exists, the Integration Service places quotes around matching reserved words when it executes SQL against the database. If you override the SQL, you must enclose any reserved word in quotes.

When generating the default query, the Designer delimits table and field names containing the following characters with double quotes: