LEFT (string, count)
Returns the left most count of characters in string. The value of count is an integer.
The following example results in first name trimmed to three characters beginning from left, the length as 9 and locate results 0. This query results in "Roo", 9, 0
SELECT LEFT(First_name, 3),LENGTH(First_name), LOCATE(First_name, 'a') FROM Person WHERE First_name = 'Roosevelt'