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  2. Set operations (SQL) - Wikipedia

    en.wikipedia.org/wiki/Set_operations_(SQL)

    The EXCEPT ALL operator does not remove duplicates, but if a row appears X times in the first query and Y times in the second, it will appear (,) times in the result set. Notably, the Oracle platform provides a MINUS operator which is functionally equivalent to the SQL standard EXCEPT DISTINCT operator.

  3. Comparison of relational database management systems - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_relational...

    An SQL schema is simply a namespace within a database; things within this namespace are addressed using the member operator dot ".". This seems to be a universal among all of the implementations. A true fully (database, schema, and table) qualified query is exemplified as such: SELECT * FROM database. schema. table

  4. Comparison of database administration tools - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_database...

    Compare Import Export Debugger Source control Spatial Visualization Adminer: Yes Yes Yes SQL script, CSV, TSV or the above in zip (as a plugin); imports of server-site file in SQL or SQL in zip, gzip or bzip2: SQL script, CSV, TSV or the above in zip, gzip, bzip2; XML (as a plugin) No Git: Altova DatabaseSpy: No No Yes CSV, XML

  5. SQL - Wikipedia

    en.wikipedia.org/wiki/SQL

    SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...

  6. Data deduplication - Wikipedia

    en.wikipedia.org/wiki/Data_deduplication

    The reasons for this are two-fold: First, data deduplication requires overhead to discover and remove the duplicate data. In primary storage systems, this overhead may impact performance. The second reason why deduplication is applied to secondary data, is that secondary data tends to have more duplicate data.

  7. Hash function - Wikipedia

    en.wikipedia.org/wiki/Hash_function

    A universal hashing scheme is a randomized algorithm that selects a hash function h among a family of such functions, in such a way that the probability of a collision of any two distinct keys is 1/m, where m is the number of distinct hash values desired—independently of the two keys. Universal hashing ensures (in a probabilistic sense) that ...

  8. Levenshtein distance - Wikipedia

    en.wikipedia.org/wiki/Levenshtein_distance

    In information theory, linguistics, and computer science, the Levenshtein distance is a string metric for measuring the difference between two sequences. The Levenshtein distance between two words is the minimum number of single-character edits (insertions, deletions or substitutions) required to change one word into the other.