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  2. Beautiful Soup (HTML parser) - Wikipedia

    en.wikipedia.org/wiki/Beautiful_Soup_(HTML_parser)

    www.crummy.com /software /BeautifulSoup / Beautiful Soup is a Python package for parsing HTML and XML documents, including those with malformed markup. It creates a parse tree for documents that can be used to extract data from HTML, [ 3 ] which is useful for web scraping .

  3. Query rewriting - Wikipedia

    en.wikipedia.org/wiki/Query_Rewriting

    Query rewriting is a typically automatic transformation that takes a set of database tables, views, and/or queries, usually indices, often gathered data and query statistics, and other metadata, and yields a set of different queries, which produce the same results but execute with better performance (for example, faster, or with lower memory use). [1]

  4. Query language - Wikipedia

    en.wikipedia.org/wiki/Query_language

    A query language, also known as data query language or database query language (DQL), is a computer language used to make queries in databases and information systems. In database systems, query languages rely on strict theory to retrieve information. [1] A well known example is the Structured Query Language (SQL).

  5. Query by Example - Wikipedia

    en.wikipedia.org/wiki/Query_by_Example

    Query by Example (QBE) is a database query language for relational databases. It was devised by Moshé M. Zloof at IBM Research during the mid-1970s, in parallel to the development of SQL. [1] It is the first graphical query language, using visual tables where the user would enter commands, example elements and conditions.

  6. Relational database - Wikipedia

    en.wikipedia.org/wiki/Relational_database

    In SQL, an INNER JOIN prevents a cartesian product from occurring when there are two tables in a query. For each table added to a SQL Query, one additional INNER JOIN is added to prevent a cartesian product. Thus, for N tables in an SQL query, there must be N−1 INNER JOINS to prevent a cartesian product.

  7. Hierarchical and recursive queries in SQL - Wikipedia

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

    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.

  8. Select (SQL) - Wikipedia

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

    Title Authors ----- ----- SQL Examples and Guide 4 The Joy of SQL 1 An Introduction to SQL 2 Pitfalls of SQL 1 Under the precondition that isbn is the only common column name of the two tables and that a column named title only exists in the Book table, one could re-write the query above in the following form:

  9. Regular expression - Wikipedia

    en.wikipedia.org/wiki/Regular_expression

    In line-based tools, it matches the starting position of any line. Matches any single character (many applications exclude newlines , and exactly which characters are considered newlines is flavor-, character-encoding-, and platform-specific, but it is safe to assume that the line feed character is included).