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  2. Merge (SQL) - Wikipedia

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

    Additionally there is a single-row version, UPDATE OR INSERT INTO tablename (columns) VALUES (values) [MATCHING (columns)], but the latter does not give you the option to take different actions on insert versus update (e.g. setting a new sequence value only for new rows, not for existing ones.)

  3. Set operations (SQL) - Wikipedia

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

    Set operations in SQL is a type of operations which allow the results of multiple queries to be combined into a single result set. [ 1 ] Set operators in SQL include UNION , INTERSECT , and EXCEPT , which mathematically correspond to the concepts of union , intersection and set difference .

  4. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    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:

  5. Help:Creating tables - Wikipedia

    en.wikipedia.org/wiki/Help:Creating_tables

    The following assumes the syntax is a whole table row in one source line starting with a pipe and with double pipe between cells. It does not work with partially compressed table wikitext either (such as for tables with row headers).

  6. 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.

  7. Relational database - Wikipedia

    en.wikipedia.org/wiki/Relational_database

    Part of this processing involves consistently being able to select or modify one and only one row in a table. Therefore, most physical implementations have a unique primary key (PK) for each row in a table. When a new row is written to the table, a new unique value for the primary key is generated; this is the key that the system uses primarily ...

  8. Select (SQL) - Wikipedia

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

    The SQL SELECT statement returns a result set of rows, from one or more tables. [1] [2] A SELECT statement retrieves zero or more rows from one or more database tables or database views. In most applications, SELECT is the most commonly used data manipulation language (DML) command.

  9. Insert (SQL) - Wikipedia

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

    Database designers that use a surrogate key as the primary key for every table will run into the occasional scenario where they need to automatically retrieve the database-generated primary key from an SQL INSERT statement for use in other SQL statements. Most systems do not allow SQL INSERT statements to return row data. Therefore, it becomes ...