COALESCE – This command is popular among many different SQL dialects. We can use it to replace NULL values. For all NULL values in the Description column, COALESCE() will replace the null with a value you include in the function. In this case, the value is "Misc". For more information about COALESCE, check the documentation.

SPLIT – This command splits a string value around a specified character and returns an array. An array is a list of values that you can access by position. In this case, the forward slash (“/”) is the character we use to split the data. The first value in the array is the month. This list is zero-indexed for the index of the first position is 0. Since we want to pull out the first value as the month, we indicate the value like this: SPLIT(InvoiceDate, "/")[0] and rename the column month. The day is the second value and its index is 1.

The third SPLIT is different. Remember that our InvoiceDate column is a string that includes a date and time. Each part of the date is seperated by a forward slash, but between the date and the time, there is only a space. Line 10 contains a nested SPLIT function that splits the string on a space delimiter.

SPLIT(InvoiceDate, " ")[0] –> Drops the time from the string and leaves the date intact. Then, we split that value on the forward slash delimiter.