Power Query doesn't have traditional looping constructs like "for" loops found in other programming languages. However, there are several ways to achieve iterative tasks using Power Query functions:

1. List.Generate Function:

This function is powerful for creating a list based on a starting value, incrementing by a step value, and reaching a defined end point. You can then use this generated list to iterate through logic or transformations.

Here's an example:

```
let
Numbers = List.Generate(0, each _ < 5, each _ + 1), // Generate list from 0 to 4
TransformedNumbers = List.Transform(Numbers, each _ * 2) // Loop and multiply each number by 2
in
TransformedNumbers // Output: {0, 2, 4, 6, 8}
```

2. Table.TransformRows Function:

This function allows you to iterate through each row of a table and perform transformations on those rows.

Here's an example:

```
let
Data = { "ID"=1, "Value"="Apple" },
TransformedData = Table.TransformRows(Data, each record =>
let
newValue = record[Value] & " Juice",
updatedRecord = {ID=record[ID], Value=newValue}
in
updatedRecord
),
in
TransformedData // Output: {ID: 1, Value: "Apple Juice"}
```

3. Custom Functions with Parameters:

You can create custom functions that take parameters and use logic within them to achieve looping behavior.

Here's a basic example (replace the logic within the function for your specific needs):

```
let
CustomLoopFunction = (list as list, action as function) =>
List.Reduce(list, null, (state, current) =>
let
newState = action(current)
in
newState
),
in
// Example usage: Double each value in a list
Result = CustomLoopFunction({1, 2, 3}, each _ * 2),
in
Result // Output: {2, 4, 6}
```

Choosing the Right Technique:

* Use `List.Generate` when you need to create a new list based on a defined sequence.
* Use `Table.TransformRows` when you want to iterate through each row in a table and modify them.
* Use custom functions with parameters for more complex scenarios requiring conditional logic or specific actions within the loop.

Remember, for complex looping tasks, consider alternative approaches like using recursive functions (functions that call themselves) if applicable to your scenario.

By understanding these techniques, you can effectively iterate through lists and tables in Power Query to achieve the desired data transformations.