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The sort-merge join (also known as merge join) is a join algorithm and is used in the implementation of a relational database management system. The basic problem of a join algorithm is to find, for each distinct value of the join attribute, the set of tuples in each relation which display that value. The key idea of the sort-merge algorithm is ...
Persist is a Java-based ORM/DAO tool. It provides only the minimal amount of functionalities necessary to map objects or maps from database queries and to statement parameters. It provides only the minimal amount of functionalities necessary to map objects or maps from database queries and to statement parameters.
The SQuirreL SQL Client is a database administration tool. It uses JDBC to allow users to explore and interact with databases via a JDBC driver. It provides an editor that offers code completion and syntax highlighting for standard SQL. It also provides a plugin architecture that allows plugin writers to modify much of the application's ...
The Jakarta Persistence Query Language (JPQL; formerly Java Persistence Query Language) is a platform-independent object-oriented query language [1]: 284, §12 defined as part of the Jakarta Persistence (JPA; formerly Java Persistence API) specification. JPQL is used to make queries against entities stored in a relational database.
It is built on top of Apache Hadoop for providing data query and analysis. [3] [4] Hive gives an SQL-like interface to query data stored in various databases and file systems that integrate with Hadoop. Traditional SQL queries must be implemented in the MapReduce Java API to execute SQL applications and queries over distributed data.
The natural join is a special case of equi-join. Natural join (⋈) is a binary operator that is written as (R ⋈ S) where R and S are relations. [6] The result of the natural join is the set of all combinations of tuples in R and S that are equal on their common attribute names. For an example consider the tables Employee and Dept and their ...
The nested set model is a technique for representing nested set collections (also known as trees or hierarchies) in relational databases.. It is based on Nested Intervals, that "are immune to hierarchy reorganization problem, and allow answering ancestor path hierarchical queries algorithmically — without accessing the stored hierarchy relation".
The values of database columns are set only by a SQL “select” statement; no other command can change their values. SQR has an array data structure. An array has one or more fields, each of one of the available types. Each field may have multiple occurrences, giving SQR the equivalent of two-dimensional arrays.