Có 20+ tài liệu thuộc chủ đề "nâng cao trình SQL."
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See also Trees. See also Columns. current, 131, 133 defined, 131 interaction, 132 nonsequenced, 133 sequenced value-equivalent, 132–33 See also Duplicates Temporal JOINs , 139–45 Temporal math, 642–45. year 2000 problem, 675–80 See also Queries. storage space, 51 usefulness, 757–60 using, 392–93 VIEWs and, 391–95 See also Tables. See also Normal forms. See also Temporal queries TIMESTAMP data type, 123,...
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Joe Celko’s SQL for Smarties: Advanced SQL Programming , Third Edition, Joe Celko. Joe Celko’s SQL Programming Style , Joe Celko. Information Visualization in Data Mining and Knowledge Discovery , Edited by Usama Fayyad, Georges G. Component Database Systems , Edited by Klaus R. The Object Data Standard: ODMG 3.0 , Edited by R. Joe Celko’s SQL for Smarties: Advanced...
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11.1 The CASE Expression 247. 11.1.1 The COALESCE() and NULLIF() Functions CASE Expressions with GROUP BY CASE, CHECK() Clauses and Logical Implication Subquery Expressions and Constants 257. 13.1 The BETWEEN Predicate 273. 16.3 The ALL Predicate and Extrema Functions 313. 16.4 The UNIQUE Predicate 314. 17.1 SELECT and JOINs 317. 17.1.1 One-Level SELECT Statement 317. 17.1.2 Correlated Subqueries in a...
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25.3 Matrix Operations in SQL 581. 25.3.1 Matrix Equality 582. 25.3.2 Matrix Addition 582. 25.3.3 Matrix Multiplication 583. 27.3 The CONTAINS Operators 612. 28.1 Adjacency List Model 624. 28.1.1 Complex Constraints Procedural Traversal for Queries 627. 28.1.3 Altering the Table 628. 28.2 The Path Enumeration Model 628. 28.2.1 Finding Subtrees and Nodes 629. 28.2.2 Finding Levels and Subordinates 630. 28.2.3...
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In fact, it was hard to share files even among programs written in the same programming language!. The actions you take on one file have no effect on other files that are not in the same program. Sets are not ordered, and the members of a set are all of the same type. When you perform an operation on a...
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When you use NULL s in math calculations, they propagate in the results so that the answer is another NULL . They sort either always high or always low in the collation sequence. The CHECK() constraint tests the rows of the table against a logical expression, which SQL calls a search condition, and rejects rows whose search condition returns FALSE...
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CREATE TABLE Bar. (bar_key INTEGER NOT NULL PRIMARY KEY, other_key INTEGER NOT NULL UNIQUE,. CREATE TABLE Schedule. (teacher_name VARCHAR(15) NOT NULL, class_name CHAR(15) NOT NULL, room_nbr INTEGER NOT NULL, period INTEGER NOT NULL,. PRIMARY KEY (teacher_name, class_name, room_nbr, period));. Okay, now consider using one constraint for each rule in the list, thus.. CREATE TABLE Schedule_1. But what happens if I...
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CREATE TABLE OrgSubscriptions. CREATE TABLE IndSubscriptions. (subscr_id INTEGER NOT NULL PRIMARY KEY. CREATE TABLE SubscriptionTypes. CREATE TABLE Subscriptions. subscr_type CHAR(1) DEFAULT 'I' NOT NULL CHECK (subscr_type IN ('I', 'O. CREATE TABLE RegisterBook (emp_name CHAR(35) NOT NULL,. sign_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP NOT NULL, sign_action CHAR (3) DEFAULT 'IN' NOT NULL. The single attribute, duration, has to be modeled as two columns...
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We will spend some time later on ways to get sequences and unique numbers inside Standard SQL without resorting to proprietary code or the use of exposed physical locators in the hardware.. It is important to isolate the execution of the code to one and only one user at a time by using SET ISOLATION = SERIALIZABLE . In the...
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ALTER DOMAIN <domain name>. Once declared, a DOMAIN can be used in place of a data type declaration on a column.. The second method would have been better if you did not have a DOMAIN and had to replicate the CHECK() clause in multiple tables in the database. is not part of Standard SQL, but has been proposed in the...
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SQL is not so pure on this rule, since you can often do procedural things to the data.. information in the database be represented in one and only one way, namely, by values in column positions within rows of tables. SQL is good here.. restatement of the fundamental requirement for primary keys.. It states that every individual scalar value in...
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CREATE TABLE Students. We still have a transitive dependency in the example—(room_nbr, time_period. (course_name, section_id)—but since the right side of the dependency is a key, it is technically in 3NF. CREATE TABLE Stuff (width INTEGER NOT NULL, length INTEGER NOT NULL, height INTEGER NOT NULL, volume INTEGER NOT NULL. The volume column is determined by the other three columns, so...
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The answer is to start by attempting to derive each of the FDs from the rest of the set. Here is a list of each of the proofs used to derive the ten fragmented FDs in the problem. An additional operation that we include here, which was not included in the axioms we listed earlier, is left reduction. The reason...
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(drug_nbr INTEGER NOT NULL PRIMARY KEY, drug_name CHAR(30) NOT NULL,. (drug_nbr INTEGER NOT NULL, start_date DATE NOT NULL, end_date DATE NOT NULL. CONSTRAINT started_before_endded CHECK(start_date <= end_date), price DECIMAL(8,2) NOT NULL,. The (end_date + INTERVAL '1' DAY) of one price will be equal to the start_date of the next price for the same drug.. (drug_nbr INTEGER PRIMARY KEY, drug_name CHAR(30)...
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102 CHAPTER 3: NUMERIC DATA IN SQL. Numbers in SQL are classified as either exact or approximate. An exact numeric value has a precision, p , and a scale, s . high-end, or low-end—and various word sizes. The proper mental model of numbers in SQL is not to worry about the “bits and bytes” level of the physical representation, but...
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As an example of the use of COALESCE. The problem is to write a query that returns the customer and the amount of the last payment he made. This can be done with the rather ugly-looking expression that will turn a month’s non NULL payment into a character string with the name of the month. 0) where ‘Month’ is replaced...
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122 CHAPTER 4: TEMPORAL DATA TYPES IN SQL. Faced with all of the possibilities, software vendors came up with various general ways of formatting dates for display. This is the “yyyy-mm-dd”. format that is part of Standard SQL and will become part of other standard programming languages as they add temporal data types.. The full ISO-8601 timestamp can be either...
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The adjective sequenced means that the constraint is applied independently at every point in time. Table 4.2 indicates how these variants interact. Each entry specifies whether rows satisfying the variant in the left column will also satisfy the variant listed across the top. A check mark states that the top variant will be satisfied. duplicates, for the entire period of...
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WHERE L1.lot_id<. L2.lot_id. AND L1.feedyard_id = L2.feedyard_id AND L1.pen_id = L2.pen_id. AND L2.from_date <= L1.from_date AND L1.to_date <= L2.to_date UNION. SELECT L1.lot_id, L2.lot_id, L1.pen_id, L1.from_date, L2.to_date FROM LotLocations AS L1,. LotLocations AS L2 WHERE L1.lot_id<. AND L1.from_date >. L2.from_date AND L2.to_date <. L1.to_date AND L1.from_date <. L2.to_date UNION. SELECT L1.lot_id, L2.lot_id, L1.pen_id, L2.from_date, L1.to_date FROM LotLocations AS L1, LotLocations AS...
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SET to_date = DATE WHERE lot_id = 234. DATE AND to_date >= DATE . SET from_date = DATE WHERE lot_id = 234. DELETE FROM Lots WHERE lot_id = 234. AND from_date >= DATE AND to_date <= DATE . A sequenced update is the temporal analog of a nontemporal update, with a specified period of applicability. SET gender_code = 's' WHERE...