Search results
Results from the WOW.Com Content Network
A true fully (database, schema, and table) qualified query is exemplified as such: SELECT * FROM database. schema. table. Both a schema and a database can be used to isolate one table, "foo", from another like-named table "foo". The following is pseudo code: SELECT * FROM database1. foo vs. SELECT * FROM database2. foo (no explicit schema ...
Each system has at least some features of an object–relational database; they vary widely in their completeness and the approaches taken. The following tables compare general and technical information; please see the individual products' articles for further information.
The following tables compare general and technical information for a number of available database administration tools. Please see individual product articles for further information. This article is neither all-inclusive nor necessarily up to date. Systems listed on a light purple background are no longer in active development.
SQL support Datatypes License Description Caché: 2017.2.1 Caché ObjectScript (dynamic language), Basic. Java/.NET object mapping supported. SQL subset. Object notation allowed. Supports embedded SQL, dynamic SQL and xDBC access. Proprietary: MUMPS ancestry. Includes built-in support for XML, Web/AJAX and an EMB system called Ensemble.
The relational algebra uses set union, set difference, and Cartesian product from set theory, and adds additional constraints to these operators to create new ones.. For set union and set difference, the two relations involved must be union-compatible—that is, the two relations must have the same set of attributes.
A table in a SQL database schema corresponds to a predicate variable; the contents of a table to a relation; key constraints, other constraints, and SQL queries correspond to predicates. However, SQL databases deviate from the relational model in many details, and Codd fiercely argued against deviations that compromise the original principles. [3]
The SQL Editor, based on RSyntaxTextArea by fifesoft.com, provides syntax highlighting. It can open, create, save and execute files containing SQL statements. SQuirreL supports simultaneous sessions with multiple databases. This allows comparing data and sharing SQL statements between databases. [4] SQuirreL runs on any platform that has a JVM.
A common table expression, or CTE, (in SQL) is a temporary named result set, derived from a simple query and defined within the execution scope of a SELECT, INSERT, UPDATE, or DELETE statement. CTEs can be thought of as alternatives to derived tables ( subquery ), views , and inline user-defined functions.