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Relational Database Management Systems and SQL
Relational Database Management Systems and SQL

... the column. Clearly we cannot allow duplicate values for the primary key. We also disallow null values, since we could not distinguish between two different records if they both had null key values, so the specification of PRIMARY KEY in SQL carries an implicit NOT NULL constraint as well as a UNIQU ...
Strong Types for Relational Data Stored in Databases or
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... boundaries in its type. If c can be assigned type Probability rather than Real, the constraint would become checkable statically. In this report, we will investigate whether more precise types can be assigned to database operations than is commonly done by the static checking components of DBMSs. Fo ...
DBMS Lab
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... Department table. But, in the Employee table all the employee records are from the first four departments only. Now a join operation on these two tables would retrieve only those rows where the department numbers are matching, i.e. either of those departments where some employee has been recruited. ...
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An Adaptive Probe-Based Technique to Optimize Join Queries in Distributed Internet Databases
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... Internet databases. We focussed on join queries because join operation is not only frequently used but also expensive [YM98]. In order to demonstrate the importance of run-time optimization, we implemented an experimental distributed database system connected through the Internet. Our setup consists ...
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No Slide Title

... Impedance mismatch: ...
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Relational Model Advanced Topics in Microsoft SQL Server

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Query Optimization In Compressed Database Systems.
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... operation in the relational database model is called the join. A join operation is a Way of combining data from tWo tables Which is typically based on the relationships betWeen the data in those tables. The Product table identi?es the product type by prod ID, and the Sales table identi?es the amount ...
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... 1. The subquery (in parentheses) produces rows of data that consist of 90% of each manager’s salary. Because the subquery is qualified by ALL, only the largest value from this table is retrieved. 2. The main query joins all rows in the ORG and STAFF tables where the department numbers are the same, ...
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... passes applications requiring a multidimensional view of data. In such a view of data there is a set of measures that are the metrics of interest. The measures contain numeric data. Each of them is uniquely determined by a set of different and often independent dimensions. Dimensions have associated ...
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... It is usually used for true/false or yes/no types of data, because it holds either 1 or 0. All integer values other than 1 or 0 are always interpreted as 1. One bit column stores in 1 byte, but multiple bit types in a table can be collected into bytes. Bit columns cannot be NULL and cannot have inde ...
Automatically Synthesizing SQL Queries from Input
Automatically Synthesizing SQL Queries from Input

... The supported SQL subset covers all top 10 most widelyused SQL features as voted by the survey participants in Figure 2, except for the IN keyword. In addition, the SQL subset supports the HAVING keyword since HAVING is often used together with the GROUP BY clause. Our SQL subset, though by no means ...
Run-Time Optimizations of Join Queries for Distributed Databases
Run-Time Optimizations of Join Queries for Distributed Databases

... heterogeneous hardware (e.g., PC and Unix workstations) connected via the Internet. Distributed databases are appropriate for organizations consisting of a number of almost independent suborganizations such as a University with many departments or a bank with many branches. The idea is to partition ...
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... parameter. On a server, every database used the same set of characters. With SQL Server 2000, the character set, sort order and Unicode collation have been grouped in what is now called a collation, which can be defined at the server, database or even column level. This means that a server can be in ...
Structured Query Language
Structured Query Language

... SQL Server uses T-SQL (Transact-SQL). T-SQL is Microsoft's proprietary extension to SQL. TSQL is very similar to standard SQL, but in addition it supports some extra functionality, builtin functions, etc. T-SQL expands on the SQL standard to include procedural programming, local variables, various ...
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Join (SQL)

A SQL join clause combines records from two or more tables in a relational database. It creates a set that can be saved as a table or used as it is. A JOIN is a means for combining fields from two tables (or more) by using values common to each. ANSI-standard SQL specifies five types of JOIN: INNER, LEFT OUTER, RIGHT OUTER, FULL OUTER and CROSS. As a special case, a table (base table, view, or joined table) can JOIN to itself in a self-join.A programmer writes a JOIN statement to identify the records for joining. If the evaluated predicate is true, the combined record is then produced in the expected format, a record set or a temporary table.
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