# Iteration
## Flow Iteration
In all operations, except the Read operation, one can use iterator to loop through several rows in one machine step. Notice, this not a BATCH call. The Flow Server will run the same machine step as many times there are rows in iterating table.
### Defining iterator
Set Iterator table
### Using iterator table variables in Input
After defining iterator table a new variable type Iterator will appear in each input parameter.
Select Iterator variable type
After which only variables from iterator table can be selected to the specified parameter.
Select column from iterator table
You can use mix of Constants and Variables, Not Set and Iterator variable in Input parameters
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