TABLE OF CONTENTS The major problem in learning SQL is that programmers are used to thinking in terms of files rather than tables.
Programming languages are usually based on some underlying model; if you understand the model, the language makes much more sense. For example, FORTRAN is based on algebra. This does not mean that FORTRAN is exactly like algebra. But if you know algebra, FORTRAN does not look all that strange to you. You can write an expression in an assignment statement or make a good guess as to the names of library functions you have never seen before.
Programmers are used to working with files in almost every other programming language. The design of files was derived from paper forms; they are very physical and very dependent on the host programming language. A COBOL file could not easily be read by a FORTRAN program, and vice versa. In fact, it was hard to share files even among programs written in the same programming language!
The most primitive form of a file is a sequence of records, ordered within the file and referenced by physical position. You open a file, then read a first record, followed by a series of next records until you come to the last record to raise the end-of-file condition. You navigate among these records and perform actions one record at a time. The actions you ...
