Extracts the left hand part of a string.
string LEFT(string value, int num)
Will return "Ac"
Another example could be to get the first 4 letters of a product name from the ProductName column, to create a short product name. In this example we will use the following two products "Data Synchronisation Studio" and "Ouvvi":
Will return "Data" for the product "Data Synchronisation Studio" and "Ouvv" for the Ouvvi product.