Có 80+ tài liệu thuộc chủ đề "nâng cao trình SQL."
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SELECT MIN(F1.seq_nbr + 1) FROM List AS F1. WHERE (L1.seq_nbr +1). FROM (SELECT L1.seq_nbr, MIN(L2.seq_nbr) FROM List AS L1, List AS L2 WHERE L1.seq_nbr <. L2.seq_nbr GROUP BY L1.seq_nbr). SELECT (L1.seq_nbr + 1) AS gap_start, (MIN(L2.seq_nbr. WHERE L1.seq_nbr <. L2.seq_nbr GROUP BY L1.seq_nbr. HAVING (MIN(L2.seq_nbr. L1.seq_nbr) >. (seq_nbr INTEGER NOT NULL PRIMARY KEY,. seq_nbr val answer . WHERE R1.seq_nbr <=...
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SELECT DISTINCT C1.x, C1.y FROM Cover AS C1. FROM Cover AS C2 WHERE C2.x <= C1.x AND C2.y >= C1.y. AND (C1.x <>. C2.x OR C1.y <>. Now we find all the holes in the range of the intervals and put them in a VIEW or a WITH clause–derived table.. SELECT seq_nbr FROM Sequence. WHERE seq_nbr <= (SELECT MAX(y) FROM...
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582 CHAPTER 25: ARRAYS IN SQL. j INTEGER NOT NULL CHECK (j >. 25.3.1 Matrix Equality. Two matrices are equal if their cardinalities and the cardinality of the their intersection are all equal.. SELECT COUNT. FROM MatrixA UNION. SELECT COUNT(*). FROM MatrixA AS A, MatrixB AS B WHERE A.i = B.i. AND A.element = B.element;. If it returns one number,...
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592 CHAPTER 26: SET OPERATIONS. For the rest of this discussion, let us create two tables with the same structure, which we can use for examples.. 26.1 UNION and UNION ALL. The two versions of the UNION statement take two tables and build a result table from them. The two tables must be union-compatible, which means that they have exactly...
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((1), (2)) for the tables given in the example.. by a coincidence of the particular values used in these tables.. At one point, when SQL was still in the laboratory at IBM, there was a CONTAINS operator that would tell you if one table was a subset of another. It disappeared in later versions of the language and no vendor...
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FROM LotteryDrawing AS L2 WHERE L1.keycol <= L2.keycol);. 27.3 The CONTAINS Operators. This predicate existed in the original System R, IBM’s first experimental SQL system, but it was dropped from later SQL implementations because of the expense of running it.. you the names of each employee who works on all of the projects in department 5. In the second SELECT...
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SELECT MIN(Memberships.member_id), MIN(Memberships.club_name, Memberships.ifc. WHERE Memberships.club_name = MissingClubs.club_name) AND Memberships.ifc = MissingIfcs.ifc. GROUP BY Memberships.ifc;. SELECT MIN(Memberships.member_id), MIN(memberships.club_name), memberships.ifc. WHERE Memberships.ifc = MissingIfcs.ifc GROUP BY Memberships.ifc;. SELECT MIN(Memberships.Member_id), Memberships.club_name, MIN(Memberships.ifc). WHERE Memberships.club_name = MissingClubs.club_name GROUP BY Memberships.club_name;. Trees and Hierarchies in SQL. I HAVE A SEPARATE book ( Joe Celko’s Trees and Hierarchies in SQL for Smarties , 2004) devoted...
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28.3 Nested Set Model of Hierarchies 633. Another nice thing is that the name of each node appears once and only once in the table. 28.3.1 The Counting Property. SELECT node AS root FROM NestTree WHERE lft = 1;. SELECT node AS leaf FROM NestTree. Another very useful result of the counting property is that any node in the tree...
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29.1 Temporal Math. Table 29.1 shows the valid combinations of <datetime>. Table 29.1 Valid Combinations of Temporal Data Types in Standard SQL. 29.2 Personal Calendars 643. Other rules, dealing with time zones and the relative precision of the two operands, are intuitively obvious.. CURRENT DATE , and getdate() are some examples. There may also be a function to return the...
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I want a select statement that will sum up the start of the cal_value and the end of the calibration value before it changes.. FROM (SELECT C1.start_time, C1.end_time, C1.cal_value, MIN(C2.start_time). ON C1.start_time <. C2.start_time AND C1.cal_value <>. C2.cal_value. GROUP BY C1.start_time, C1.end_time, C1.cal_value) AS T (start_time, end_time, cal_value, x_time)) GROUP BY cal_value, x_time;. (event_id CHAR(2) NOT NULL PRIMARY KEY, start_date...
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The fixed point is usually the year 1, or 1900, or the start of the Gregorian calendar.. A Julianized, or ordinal, date is the position of the date within its year, so it falls between 1 and 365 or 366. The usual way to find the Julianized day within the current year is to use a simple program that stores...
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This will let us use BETWEEN predicates, as we will see in the next section. 29.8.1 Using Duration Pairs. SELECT P.proj_id, P.proj_name FROM Projects AS P. FROM ProjectStatusHistory AS H WHERE H.proj_id = P.proj_id. HAVING MAX(CASE WHEN H.proj_status = 10. SELECT X.proj_id. FROM (SELECT P1.proj_id, P1.proj_date AS start_date, MIN(P2.proj_date) AS end_date. ON P1.proj_id = P2.proj_id. AND P1.proj_date <. P2.proj_date WHERE...
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30.1 Basic Graph Characteristics. CHECK (begin_node_id <>. end_node_id));. 30.1.1 All Nodes in the Graph. To view all nodes in the graph, use the following:. 30.1 Basic Graph Characteristics 683. CREATE VIEW GraphNodes (node_id) AS. SELECT DISTINCT node_id FROM NestedSetsGraph;. 30.1.2 Path Endpoints. Path endpoints are the first and last nodes of each path in the graph.. CREATE VIEW PathEndpoints (begin_node_id,...
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The last step column is the end of the journey. The total_cost column is the total cost, based on the sum of the weights of the edges, on this path. The path length column is harder to explain, but for now, let’s just say that it is a count of the nodes visited in the path.. To keep things easier,...
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arrival_town steps total_distance. The girl hiding in the cake is the ability to determine which different towns we visit by using each of these different routes:. WITH RECURSIVE Journeys (arrival_town, steps, total_distance, way) AS (SELECT DISTINCT depart_town, 0, 0,. CAST('PARIS' AS VARCHAR(MAX)) FROM Journeys. WHERE depart_town = 'PARIS' UNION ALL. SELECT arrival_town, Departures.steps + 1,. Departures.total_distance + Arrivals.jny_distance, Departures.way. ||Arrivals.arrival_town...
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712 CHAPTER 31: OLAP IN SQL. defined by an ordering clause (if one is specified), starting with one for the first row and continuing sequentially to the last row in the window.. If an ordering clause, ORDER BY , isn’t specified in the window, the row numbers are assigned to the rows in arbitrary order as returned by the subselect.....
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722 CHAPTER 32: TRANSACTIONS AND CONCURRENCY CONTROL. This will be dealt with in detail in the section on isolation levels.. 32.2.4 Durability. The database is stored on durable media, so that if the database program is destroyed, the database itself persists. Furthermore, the database can be restored to a consistent state when the database system is restored.. This is all...
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CA-Ingres has one of the best optimizers, which extensively reorders a query before executing it. It is one of the few products that can find most semantically identical queries and reduce them to the same internal form.. DB2 has a system table with a statistical profile of the base tables.. In short, no two products use exactly the same optimization...
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that 80% of the queries will use the PRIMARY KEY and 20% will use another (near-random) column.. This is pretty much what you would know in a real-world situation, since most of the accessing will be done by production programs with embedded SQL in them. 33.5 Watch the IN Predicate. The database engine has no statistics about the relative frequency...
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“SQL Matrix Processing.” Database Programming and Design (August).. “Two Fast Implementations of the ‘Minimal Stan- dard’ Random Number Generator.” Communications of the ACM 33(1):87.. “Simple but Effective Modifica- tion to a Multiplicative Congruential Random-number Generator.” IEEE Proceedings: Computers and Digital Technology . “An Optimal Random Number Generator Zp.” Statis- tics and Probability Letters 7(4):307.. “A Highly Random-number Generator.” Computer Language...