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SSIS - Precedence Contraints

. It is link created between the Containers, executables, tasks or any control flow elements.
. For example, to view a Precedence Constarint Editor, create two script tasks.
. select a task, it displays a arrows pointing downwards, drag and drop the arrow to the second script task.
. a conector is created in between the tasks. it is called Precedence constaint.
. the default value set to the constraint is success.
. to view the editor, select the connector, right click and select edit from the context menu.
. a dialog box opens with fields, evaluvation operation, constaint and expression.
. the flow can set as per the condition defined here.
. the condition can be set to Constraint, with following values,
1. Success - allows to flow only if the previous task executed succesfully.
2. Failure - allows to flow only if the previous task fail to execute.
3. Completion - allows to flow, without considering the execute status of previous task.
. the condition can be set to Expression. the flow depends on the result of the expression.
. the condition can be set to Constaint or Expression, where both will be defined and flow will be decided by any one.
. the condition can be set to Constraint and Expression, where both will be defined and flow will proceed only if both are passed.
. Multiple Precedence Constraints may contain for a task, in that case the logical Or and And between the Precedence Constraints can also be set using the editor.

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