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  2. Set operations (SQL) - Wikipedia

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

    The EXCEPT ALL operator does not remove duplicates, but if a row appears X times in the first query and Y times in the second, it will appear (,) times in the result set. Notably, the Oracle platform provides a MINUS operator which is functionally equivalent to the SQL standard EXCEPT DISTINCT operator. [3]

  3. List of Java bytecode instructions - Wikipedia

    en.wikipedia.org/wiki/List_of_Java_bytecode...

    This is a list of the instructions that make up the Java bytecode, an abstract machine language that is ultimately executed by the Java virtual machine. [1] The Java bytecode is generated from languages running on the Java Platform, most notably the Java programming language.

  4. Relational algebra - Wikipedia

    en.wikipedia.org/wiki/Relational_algebra

    The relational algebra uses set union, set difference, and Cartesian product from set theory, and adds additional constraints to these operators to create new ones.. For set union and set difference, the two relations involved must be union-compatible—that is, the two relations must have the same set of attributes.

  5. Union type - Wikipedia

    en.wikipedia.org/wiki/Union_type

    The memory layout of unions in Rust is undefined by default, [8] but a union with the #[repr(C)] attribute will be laid out in memory exactly like the equivalent union in C. [9] Reading the fields of a union can only be done within an unsafe function or block, as the compiler cannot guarantee that the data in the union will be valid for the ...

  6. Project Valhalla (Java language) - Wikipedia

    en.wikipedia.org/wiki/Project_Valhalla_(Java...

    Valhalla is incubating Java language features and enhancements in these areas: [2] [3] Value Classes and Objects: highly-efficient objects without their own identity (reference value). Null-restricted and Nullable types, and Null-restricted Objects: for example, using ? or ! after type declaration to say if null is allowed or not.

  7. Relational database - Wikipedia

    en.wikipedia.org/wiki/Relational_database

    The union operator (υ) combines the tuples of two relations and removes all duplicate tuples from the result. The relational union operator is equivalent to the SQL UNION operator. The intersection operator (∩) produces the set of tuples that two relations share in common. Intersection is implemented in SQL in the form of the INTERSECT operator.

  8. Java syntax - Wikipedia

    en.wikipedia.org/wiki/Java_syntax

    For example, java.io.InputStream is a fully qualified class name for the class InputStream which is located in the package java.io. A package is declared at the start of the file with the package declaration:

  9. Comparison of ALGOL 68 and C++ - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_ALGOL_68_and_C++

    Assigning values into an A68 union variable is automatic, the type is "tagged" to the variable, but pulling the value back out is syntactically awkward as a conformity-clause is required. ALGOL 68 example: union(int, char) x:=666; printf(($3d l$, (x|(int i):i) )) C++ example: