an introduction to objectoriented programming in c pdf

... drag in the (in our experience, rather confusing and unhelpful) terms and concepts result covariance and argument contravariance "Result contravariance" is just an obvious consequence ... there are clearly more colored circles than there are circles And colored circles can't be obtained from circles via S by C, either Note the remark to the effect that "COLORED_CIRCLE is a ... declared types) • We consider single inheritance only in this chapter, for simplicity, though our model in fact supports multiple inheritance too • We consider scalar inheritance only in

Ngày tải lên: 06/08/2014, 01:21

... very clearly defined (certainly it's not very precise) After all, even a number might be decomposed (e.g., into decimal digits, or into integer and fractional parts) in suitable circumstances; ... articulated in reference [6.2] See references [6.7] and [6.8] for some specific criticisms Answers to Exercises 6.1 Fundamentally, cardinality is a concept that applies to sets: The cardinality ... separate topic out of them in a live class Relations with No Attributes A gentle introduction to this concept is DEFINITELY worth including as a separate topic Strong logical justification: TABLE_DEE

Ngày tải lên: 06/08/2014, 01:21

... thing as an <aggregate operator invocation> An <aggregate operator invocation> is a scalar expression and can appear wherever a scalar selector invocation──in particular, a scalar ... type) In fact, when we say that INTERSECT is Trang 10a special case of JOIN, what we really mean is that every specific INTERSECT is a special case of some specific JOIN Let S_JOIN be such a specific ... for JOIN generically, but we can't do the same for INTERSECT──we can define the result only for specific INTERSECT operations (i.e., INTERSECT operations that are specific to some particular

Ngày tải lên: 06/08/2014, 01:21

... operand column-naming requirements are indeed satisfied──the SQL column name inheritance rules in fact coincide with those of the algebra as described (under the name relation type inference) in ... than the original calculus (or algebra) We therefore need another extension to the original calculus (and algebra) The TCLOSE operator discussed briefly in Chapter 7 is part of the solution to ... (algebraic) operators restrict, project, product, union, and difference, and then (b) that the operands to those SQL expressions can be arbitrary SQL expressions in turn We begin by observing that

Ngày tải lên: 06/08/2014, 01:21

... NK In other words, to say that R has a nullary key is to constrain R to contain at most one tuple, and such a constraint could certainly be useful in some circumstances [6.5] Note that Tutorial ... constraints from TEACHER to OFFERING, ENROLLMENT to OFFERING, and OFFERING to COURSE are all properly maintained, the referential constraints from TEACHER to COURSE and ENROLLMENT to COURSE will ... concentrating on in this chapter so far The difference between them isn't──and in fact can't be, thanks to The Principle of Interchangeability of Base and Derived Relvars, which we'll be discussing in the

Ngày tải lên: 06/08/2014, 01:21

... from the main theme of the chapter It's included partly (a) because snapshots are becoming increasingly important in practice, thanks to the growing use of (asynchronous) replication and data warehouse ... JOIN SR? Answer: a Inserting the tuple (s,sn,st,sc,rt) into the join is equivalent to inserting the tuple (s,sn,st,sc) into S (unless it's already present) and inserting the tuple (s,rt) into ... actions) into account UPDATE is shorthand for a DELETE-then-INSERT sequence (loosely speaking) INSERTs map to INSERTs and DELETEs map to DELETEs The mechanism must be recursive We can't assume

Ngày tải lên: 06/08/2014, 01:21

... operator in its own special way──special rules for union, special rules for divide, and so on Everything becomes a special case (in fact, consistency dictates inconsistency!) This surely can't ... Trang 1R"──assuming the INSERTs and DELETEs all succeed, of course.) ■ Again, if we decide to treat join views in some special way, then consistency dictates that we treat EACH AND EVERY ... Especially since, in the example of S JOIN SP, we can achieve the desired DELETE behavior by applying the DELETE direct to relvar SP instead of to the join view! Of course, nothing in the foregoing

Ngày tải lên: 06/08/2014, 01:21

... tuple of R is lost by taking the projections and then joining those projections back together again Let (a,b,c) ε R Then (a,b) ε R1 and (a,c) ε R2, and so (a,b,c) ε R1 JOIN R2 Next we show that ... America in every tuple) Then the FD { } → COUNTRY holds in this relvar, and yet the empty set {} is not a candidate key So USA isn't in BCNF (it can be nonloss-decomposed into its two unary projections──though ... XPROJ0, and XOFFICE0 from DEPT0 • If any relvar R still includes any RVAs, perform an analogous sequence of operations on R We obtain the following collection of relvars, with (as indicated)

Ngày tải lên: 06/08/2014, 01:21

... relvar CTX (algebraic version): Trang 3CONSTRAINT CTX_MVD CTX = CTX { COURSE, TEACHER } JOIN CTX { COURSE, TEXT } ; Calculus version: CONSTRAINT CTX_MVD CTX = { CTXX.COURSE, CTXX.TEACHER, CTXY.TEXT ... WHERE CTXD1.COURSE = CTXD2.COURSE AND CTXD1.TEACHER = CTXD2.TEACHER AND CTXD1.TEXT = CTXD2.TEXT ) AND ( NOT EXISTS ( SELECT DISTINCT COURSE, TEACHER, TEXT FROM ( ( SELECT DISTINCT COURSE, TEACHER ... as an exercise." Answer: CONSTRAINT EMVD_ON_CTXD CTXD { COURSE, TEACHER, TEXT } = CTXD { COURSE, TEACHER } JOIN CTXD { COURSE, TEXT } ; Note that this constraint is much harder to state in

Ngày tải lên: 06/08/2014, 01:21

... scheme if it wants to.) Explain phantoms and the basic idea (only) of predicate locking Mention access path locking as an implementation of predicate locking 16.9 Intent Locking This is good ... here in any special technical sense──in particular, not in the formal sense of Chapter 21 ────────── By analogy with intuitive examples such as the foregoing, concurrency control in transaction ... Discuss locking granularity and corresponding tradeoffs Conflict detection requires intent locks: intent shared (IS), intent exclusive (IX), and shared intent exclusive (SIX) Discuss the intent

Ngày tải lên: 06/08/2014, 01:21

... form 2 Convert to canonical form 3 Choose candidate low-level procedures 4 Generate query plans and choose the cheapest In practice, Stage 1 effectively becomes "convert the SQL query to a ... relevant to the second aspect, except inasmuch as its clean logical vs physical separation is what permits so many different access paths to be deployed (physical data independence) Commercial optimizers ... counterpart to RUNSTATS) 18.6 A Divide-and-Conquer Strategy This section describes the historically important Ingres query decomposition approach and can serve as a springboard for getting into

Ngày tải lên: 06/08/2014, 01:21

... OLAP Analytical processing always implies data aggregation, usually according to many different groupings. In classical relational languages (and in SQL too, prior to SQL:1999), each individual ... variables (relvars); Copyright (c) 2003 C. J. Date page 22.2 we use logical schema and physical schema in place of conceptual schema and internal schema. The chapter can be skipped or skimmed ... system──conflicts arise over capacity planning, resource management, and system performance tuning, among other things. For such reasons, operational system administrators are usually reluctant to

Ngày tải lên: 06/08/2014, 01:21

... us to define all of the new operators and other constructs that we need to formulate queries, constraints, and so forth in an intellectually manageable way. 23.4 INTERVAL_INTEGER ( [ BEGIN(i) ... the combination of a universe of discourse, plus the mapping of individual constants to objects in that universe, plus the defined meanings for the predicates and functions with respect to ... operators l S ( s,... applicability of object concepts and technology to database management specifically Please understand, therefore, that all remarks made in this chapter concerning object

Ngày tải lên: 06/08/2014, 01:21

... contains ( J contains ( P ) ) S contains ( P and J ) P contains ( J contains ( S ) ) P contains ( S contains ( J ) ) P contains ( J and S ) J contains ( S contains ( P ) ) J contains ( P contains ... ESET instances, and any subset of those ESET instances could include a reference to some specific employee 25.10 There are at least nine possible hierarchies: S contains ( P contains ( J ) ) S contains ... "An object is an abstract machine that defines a protocol through which users of the object may interact" (from the introduction to reference [25.42]) • "An object is a software structure

Ngày tải lên: 06/08/2014, 01:21

... main block On most platforms, you can compile and run this program using the ubiquitous GNU C compiler, gcc . e command to compile a C+ + program is g++ , which is a program that calls gcc ... and endl . Manipulators are implicit calls to functions that can change the state of a stream object in various ways. A manipulator can be added to • An output stream to change the way the output ... project le. In such a case you might see TEMPLATE = subdirs in the project le located in the parent directory, which would cause a Makefile to be produced in the parent directory and in each...

Ngày tải lên: 24/03/2014, 01:21

... it can print primitive data to the console. All characters printed by a PrintSteam object are converted into bytes using the platform's default character encoding. One interesting and convenient ... Graphical User Interfaces 12 The Input/Output Package Figure 1.2 Chaining streams together Chaining is achieved by passing a stream object into the constructor of another stream object, as ... streams can be chained together in order to read characters and strings and numbers from the keyboard. String Input via the Keyboard The following class chains three streams in order to read characters...

Ngày tải lên: 18/03/2014, 02:20

... always Program to an interface and not to an implementation. Putting this more succinctly, you should define the top of any class hierarchy with an abstract class or an interface, which implements ... C# Increment and Decrement Operators Like Java and C/ C++ , C# allows you to express incrementing and decrementing of integer variables using the ++and operators. You can apply these to the ... system. Characters and strings in C# are always 16 bits wide: to allow for representation of characters in non-Latin languages. It uses a character coding system called Unicode, in which thousands...

Ngày tải lên: 18/10/2013, 17:15