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Archive for July, 2014

What are SQL Query Hints?

July 5, 2014 Leave a comment

SQL server usually selects the best query plan required to execute a T-SQL query. However, there might be cases where the plans selected are not the best. In such situations, you can use the query hints to suggest the best possible plan/method of executing a query. The Query hints can be applied on all operators in a query. These hints apply to SELECT, DELETE, INSERT, UPDATE and MERGE. You can use the Query hints in the OPTION clause after the query.

Few commonly used Query hints with examples are as below.

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SSIS : Using and Configuring For Loop Container

July 5, 2014 Leave a comment

What is For Loop Container?

For loop defines a repeating control flow. It has similar behavior as the “FOR” loop available in programming languages.  The For Loop container uses 3 expressions as definition

  1. Initialization expression:  it assigns value to the loop counters. This expression is optional.
  2. Evaluation expression : It contains the expression to test whether the loop should continue executing  or exit.
  3. An optional iteration expression that increments or decrements the loop counter.

The expressions used must be valid SSIS expression. A variable is generally used in the expression.

Using and Configuring For Loop Container

(Task in hand: print counter variable value for each iteration times.)

Drag a for loop container into the SSIS Control flow window from the Toolbox. Double click on the for loop container to view the “For Loop Editor”. As mentioned earlier it contains 3 expressions. Now create a variable by name “TestVariable” of type “int32”.

Use this variable as counter in the container using expressions as shown below.

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