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E. F. Codd mentioned nulls as a method of representing missing data in the relational model in a 1975 paper in the FDT Bulletin of ACM-SIGMOD.Codd's paper that is most commonly cited with the semantics of Null (as adopted in SQL) is his 1979 paper in the ACM Transactions on Database Systems, in which he also introduced his Relational Model/Tasmania, although much of the other proposals from ...
The null coalescing operator is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, such as (in alphabetical order): C# [1] since version 2.0, [2] Dart [3] since version 1.12.0, [4] PHP since version 7.0.0, [5] Perl since version 5.10 as logical defined-or, [6] PowerShell since 7.0.0, [7] and Swift [8] as nil-coalescing operator.
MySQL, MS SQL Server, PostgreSQL, Oracle, IBM Db2: Windows Visual Studio Extension 2005 Open ModelSphere: Grandite Enterprises - SMBs - personal Open source MS SQL Server, MySQL, PostgreSQL, Oracle, IBM Db2: Windows, macOS, Linux Standalone with Data, UML, and process modeling 2008 Oracle SQL Developer Data Modeler Oracle: Enterprises Proprietary
Oracle Database (commonly referred to as Oracle DBMS, Oracle Autonomous Database, or simply as Oracle) is a proprietary multi-model [4] database management system produced and marketed by Oracle Corporation. It is a database commonly used for running online transaction processing (OLTP), data warehousing (DW) and mixed (OLTP & DW) database ...
SQL Plus-internal variables, accessible within an SQL Plus session, include: user variables, displayable with the DEFINE command and referenceable with one or two cases of a prefixed character (default prefixes: '&' and '&&'). Oracle Corporation calls these variables "substitution variables".
Note (6): Can be implemented using Function-based Indexes in Oracle 8i and higher, but the function needs to be used in the sql for the index to be used. Note (7): A PostgreSQL functional index can be used to reverse the order of a field.
SQLite: A VIEW named "dual" that works the same as the Oracle "dual" table can be created as follows: CREATE VIEW dual AS SELECT 'x' AS dummy; SAP HANA has a table called DUMMY that works the same as the Oracle "dual" table. Teradata database does not require a dummy table. Queries like 'select 1 + 1' can be run without a "from" clause/table name.
COALESCE, an SQL function that selects the first non-null from a range of values; Null coalescing operator, a binary operator that is part of the syntax for a basic conditional expression in several programming languages; Coalesced hashing, a strategy of hash collision resolution in computing