LEFT(string,length[,pad])

The first two mandatory parameters are a string and a length. The result
of this function is the leftmost "length" characters of string. If
string has fewer than this many characters, then it is padded up to the
required length with spaces on the right, or, if the pad character is
given, with this character.

Examples: left("12345",2) = "12"   left("123",5,"0") = "12300"