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  2. Merge (SQL) - Wikipedia

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

    Merge (SQL) A relational database management system uses SQL MERGE (also called upsert) statements to INSERT new records or UPDATE existing records depending on whether condition matches. It was officially introduced in the SQL:2003 standard, and expanded [citation needed] in the SQL:2008 standard.

  3. Wikipedia : Advanced table formatting

    en.wikipedia.org/wiki/Wikipedia:Advanced_table...

    The answer is that when the table has a row without containing any rowspan=1 cell, this row is "compressed" upwards and disappears. Solution: divide one of the tall cells so that the row gets one rowspan=1 cell (and don't mind the eventual loss of text-centering). Then kill the border between them.

  4. Memory refresh - Wikipedia

    en.wikipedia.org/wiki/Memory_refresh

    The storage cells on a memory chip are laid out in a rectangular array of rows and columns. The read process in DRAM is destructive and removes the charge on the memory cells in an entire row, so there is a column of specialized latches on the chip called sense amplifiers, one for each column of memory cells, to temporarily hold the data ...

  5. Help:Table - Wikipedia

    en.wikipedia.org/wiki/Help:Table

    A table is an arrangement of columns and rows that organizes and positions data or images. Tables can be created on Wikipedia pages using special wikitext syntax, and many different styles and tricks can be used to customise them.

  6. Relational database - Wikipedia

    en.wikipedia.org/wiki/Relational_database

    A relational database (RDB[1]) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. [2] A database management system used to maintain relational databases is a relational database management system (RDBMS). Many relational database systems are equipped with the option of using SQL (Structured Query Language ...

  7. Merge sort - Wikipedia

    en.wikipedia.org/wiki/Merge_sort

    In computer science, merge sort (also commonly spelled as mergesort and as merge-sort [2]) is an efficient, general-purpose, and comparison-based sorting algorithm.Most implementations produce a stable sort, which means that the relative order of equal elements is the same in the input and output.

  8. Data compression - Wikipedia

    en.wikipedia.org/wiki/Data_compression

    Data compression. In information theory, data compression, source coding, [1] or bit-rate reduction is the process of encoding information using fewer bits than the original representation. [2] Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy.

  9. Relational algebra - Wikipedia

    en.wikipedia.org/wiki/Relational_algebra

    Relational algebra. In database theory, relational algebra is a theory that uses algebraic structures for modeling data, and defining queries on it with well founded semantics. The theory was introduced by Edgar F. Codd. The main application of relational algebra is to provide a theoretical foundation for relational databases, particularly ...