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  2. Insert (SQL) - Wikipedia

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

    INSERT INTO phone_book (name, number) VALUES ('John Doe', '555-1212'); Shorthand may also be used, taking advantage of the order of the columns when the table was created. It is not required to specify all columns in the table since any other columns will take their default value or remain null :

  3. Merge (SQL) - Wikipedia

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

    It also supports >REPLACE INTO syntax, [6] which first attempts an insert, and if that fails, deletes the row, if exists, and then inserts the new one. There is also an IGNORE clause for the INSERT statement, [7] which tells the server to ignore "duplicate key" errors and go on (existing rows will not be inserted or updated, but all new rows ...

  4. 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 ...

  5. Data deduplication - Wikipedia

    en.wikipedia.org/wiki/Data_deduplication

    The individual entries have a copy-on-write behavior that is non-aliasing, i.e. changing one copy afterwards will not affect other copies. [9] Microsoft's ReFS also supports this operation. [10] Target deduplication is the process of removing duplicates when the data was not generated at that location.

  6. Universally unique identifier - Wikipedia

    en.wikipedia.org/wiki/Universally_unique_identifier

    On POSIX systems, local-domain numbers 0 and 1 are for user ids and group ids respectively, and other local-domain numbers are site-defined. [8] On non-POSIX systems, all local domain numbers are site-defined. The ability to include a 40-bit domain/identifier in the UUID comes with a tradeoff.

  7. Extract, transform, load - Wikipedia

    en.wikipedia.org/wiki/Extract,_transform,_load

    Splitting a column into multiple columns (e.g., converting a comma-separated list, specified as a string in one column, into individual values in different columns) Disaggregating repeating columns; Looking up and validating the relevant data from tables or referential files

  8. Duplicate code - Wikipedia

    en.wikipedia.org/wiki/Duplicate_code

    In computer programming, duplicate code is a sequence of source code that occurs more than once, either within a program or across different programs owned or maintained by the same entity. Duplicate code is generally considered undesirable for a number of reasons. [ 1 ]

  9. Data analysis - Wikipedia

    en.wikipedia.org/wiki/Data_analysis

    By splitting the data into multiple parts, we can check if an analysis (like a fitted model) based on one part of the data generalizes to another part of the data as well. [144] Cross-validation is generally inappropriate, though, if there are correlations within the data, e.g. with panel data . [ 145 ]