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Chapter 52: Building, Deploying, and Managing ETL Workfl ows in Integration Services
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@[User::foo] == 17 && CustomerID < 100 returns true if the variable foo
equals 17 AND the CustomerID column is less than 100.■ (^) String constants are enclosed in double quotes, and special characters are C-like
backslash escape sequences, such as \n for new line and \t for tab.
■ (^) The cast operator works by describing the target type in parentheses immedi-
ately before the value to be converted. For example, (DT_I4)"193" will convert
the string “193” to a four-byte integer. The cast operator is often used inside a
Derived Column transform to achieve data conversions, often with other logic in
the expression.
■ Functions mostly come from the Transact-SQL world, including the familiar date
(GETDATE(), DATEADD(), YEAR()), string (SUBSTRING(), REPLACE(),
LEN()), and mathematical (CEILING(), SIGN()) entries. Newly added with this
release is the familiar T-SQL ISNULL() expression. Details in syntax sometimes do
differ from standard T-SQL, however, so use the Expression Builder, as shown in
Figure 52-13, or Books Online to check availability and syntax.
FIGURE 52-13
The ever-helpful Expression Builder.
Using Package Logging
Because many packages are destined for unattended operation, generating an execution
log is an excellent method for tracking operations and collecting debug information. To
confi gure package level, customized logging for a package at its design time, right-click the
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