Search results
Results from the WOW.Com Content Network
AutoNumber is a type of data used in Microsoft Access tables to generate an automatically incremented numeric counter. It may be used to create an identity column which uniquely identifies each record of a table. Only one AutoNumber is allowed in each table. The data type was called Counter in Access 2.0. [1]
The input and output domains may be the same, such as for SUM, or may be different, such as for COUNT. Aggregate functions occur commonly in numerous programming languages, in spreadsheets, and in relational algebra. The listagg function, as defined in the SQL:2016 standard [2] aggregates data from multiple rows into a single concatenated string.
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.
The SQL language is subdivided into several language elements, including: Keywords are words that are defined in the SQL language. They are either reserved (e.g. SELECT, COUNT and YEAR), or non-reserved (e.g. ASC, DOMAIN and KEY). List of SQL reserved words. Identifiers are names on database objects, like tables, columns and schemas. An ...
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
High-cardinality column values are typically identification numbers, email addresses, or user names. An example of a data table column with high-cardinality would be a USERS table with a column named USER_ID. This column would contain unique values of 1-n. Each time a new user is created in the USERS table, a new number would be created in the ...
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.
In relational databases, the information schema (information_schema) is an ANSI-standard set of read-only views that provide information about all of the tables, views, columns, and procedures in a database. [1]