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  2. Join (SQL) - Wikipedia

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

    If NULL join columns are to be deliberately removed from the result set, an inner join can be faster than an outer join because the table join and filtering is done in a single step. Conversely, an inner join can result in disastrously slow performance or even a server crash when used in a large volume query in combination with database ...

  3. Relational algebra - Wikipedia

    en.wikipedia.org/wiki/Relational_algebra

    The right outer join of relations R and S is written as R S. [e] The result of the right outer join is the set of all combinations of tuples in R and S that are equal on their common attribute names, in addition to tuples in S that have no matching tuples in R. [citation needed] For example, consider the tables Employee and Dept and their right ...

  4. Block nested loop - Wikipedia

    en.wikipedia.org/wiki/Block_nested_loop

    A block-nested loop (BNL) is an algorithm used to join two relations in a relational database. [1]This algorithm [2] is a variation of the simple nested loop join and joins two relations and (the "outer" and "inner" join operands, respectively).

  5. Relational model - Wikipedia

    en.wikipedia.org/wiki/Relational_model

    A database organized in terms of the relational model is a relational database. ... These include semi-join, outer operators such as outer join and outer union, and ...

  6. Relational database - Wikipedia

    en.wikipedia.org/wiki/Relational_database

    The join operation defined for relational databases is often referred to as a natural join (⋈). In this type of join, two relations are connected by their common attributes. MySQL's approximation of a natural join is the Inner join operator. In SQL, an INNER JOIN prevents a cartesian product from occurring when there are two tables in a query.

  7. Nested loop join - Wikipedia

    en.wikipedia.org/wiki/Nested_loop_join

    algorithm nested_loop_join is for each tuple r in R do for each tuple s in S do if r and s satisfy the join condition then yield tuple <r,s> This algorithm will involve n r *b s + b r block transfers and n r +b r seeks, where b r and b s are number of blocks in relations R and S respectively, and n r is the number of tuples in relation R.

  8. Sort-merge join - Wikipedia

    en.wikipedia.org/wiki/Sort-merge_join

    The sort-merge join (also known as merge join) is a join algorithm and is used in the implementation of a relational database management system. The basic problem of a join algorithm is to find, for each distinct value of the join attribute, the set of tuples in each relation which display that value. The key idea of the sort-merge algorithm is ...

  9. Talk:Join (SQL) - Wikipedia

    en.wikipedia.org/wiki/Talk:Join_(SQL)

    Both by itself, and inside Inner Join. The two should be merged. ★NealMcB★ 00:46, 23 December 2015 (UTC) NATURAL JOIN is just a special case, of either INNER JOIN or OUTER JOIN. Keep things together, i.e. no main section for NATURAL JOIN. Also JOIN USING syntax should be placed under INNER and OUTER JOIN.