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  2. Condition (SQL) - Wikipedia

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

    In addition to basic equality and inequality conditions, SQL allows for more complex conditional logic through constructs such as CASE, COALESCE, and NULLIF. The CASE expression, for example, enables SQL to perform conditional branching within queries, providing a mechanism to return different values based on evaluated conditions. This logic ...

  3. Hierarchical and recursive queries in SQL - Wikipedia

    en.wikipedia.org/wiki/Hierarchical_and_recursive...

    It's possible, for example, to name the result using CREATE [RECURSIVE] VIEW. [16] Using a CTE inside an INSERT INTO , one can populate a table with data generated from a recursive query; random data generation is possible using this technique without using any procedural statements.

  4. Database index - Wikipedia

    en.wikipedia.org/wiki/Database_index

    In the phone book example with a composite index created on the columns (city, last_name, first_name), if we search by giving exact values for all the three fields, search time is minimal—but if we provide the values for city and first_name only, the search uses only the city field to retrieve all matched records.

  5. MultiValue database - Wikipedia

    en.wikipedia.org/wiki/MultiValue_database

    In a MultiValue database system: a database or schema is called an "account" a table or collection is called a "file" a column or field is called a field or an "attribute", which is composed of "multi-value attributes" and "sub-value attributes" to store multiple values in the same attribute. a row or document is called a "record" or "item"

  6. List of column-oriented DBMSes - Wikipedia

    en.wikipedia.org/wiki/List_of_column-oriented_DBMSes

    Database name Language implemented in Notes Apache Doris Java & C++ Open source (since 2017), database for high-concurrency point queries and high-throughput analysis. Apache Druid: Java Started in 2011 for low-latency massive ingestion and queries. Support and extensions available from Imply Data. Apache Kudu: C++

  7. Cardinality (SQL statements) - Wikipedia

    en.wikipedia.org/wiki/Cardinality_(SQL_statements)

    High-cardinality refers to columns with values that are very uncommon or unique. High-cardinality column values are typically identification numbers, email addresses, or user names. An example of a data table column with high-cardinality would be a USERS table with a column named USER_ID. This column would contain unique values of 1-n. Each ...

  8. Lookup table - Wikipedia

    en.wikipedia.org/wiki/Lookup_table

    In 493 AD, Victorius of Aquitaine wrote a 98-column multiplication table which gave (in Roman numerals) the product of every number from 2 to 50 times and the rows were "a list of numbers starting with one thousand, descending by hundreds to one hundred, then descending by tens to ten, then by ones to one, and then the fractions down to 1/144 ...

  9. Rocket U2 - Wikipedia

    en.wikipedia.org/wiki/Rocket_U2

    123-45-6789^JOHN JONES^jjones@example.com]johnnyjones@example.net^432100^... where the close bracket (]) represents a value mark. Since each email address can be the ID of a record in separate file (in SQL terms, an outer join ; in U2 terms, a "translate"), this provides the reason why U2 may be classified as a MultiValued database.

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