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The most common operation in SQL, the query, makes use of the declarative SELECT statement. SELECT retrieves data from one or more tables, or expressions. Standard SELECT statements have no persistent effects on the database. Some non-standard implementations of SELECT can have persistent effects, such as the SELECT INTO syntax provided in some databases. [2]
W3Schools is a freemium educational website for learning coding online. [1] [2] Initially released in 1998, it derives its name from the World Wide Web but is not affiliated with the W3 Consortium. [3] [4] W3Schools offers courses covering many aspects of web development. [5] W3Schools also publishes free HTML templates. It is run by Refsnes Data in Norway. [6] It has an online text editor ...
^ Chuck, Murray (June 2009). "Data Modeler Concepts and Usage" (PDF). Oracle SQL Developer Data Modeler User’s Guide Release 2.0. Oracle Corporation. p. 1-1. Retrieved 2010-03-12. SQL Developer Data Modeler is a data modeling and database design tool that provides an environment for capturing, modeling, managing, and exploiting metadata. [...] SQL Developer Data Modeler is a for-cost option ...
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 ...
NoSQL (originally referring to "non- SQL " or "non-relational") [1] is an approach to database design that focuses on providing a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases. Instead of the typical tabular structure of a relational database, NoSQL databases house data within one data structure. Since this ...
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. As SQL is a declarative programming language, SELECT queries specify a result set, but do not specify how to calculate it. The database translates the query into a "query plan" which may vary between ...
An inner join (or join) requires each row in the two joined tables to have matching column values, and is a commonly used join operation in applications but should not be assumed to be the best choice in all situations. Inner join creates a new result table by combining column values of two tables (A and B) based upon the join-predicate. The query compares each row of A with each row of B to ...
MySQL, for example, supports the use of INSERT ... ON DUPLICATE KEY UPDATE syntax [5] which can be used to achieve a similar effect with the limitation that the join between target and source has to be made only on PRIMARY KEY or UNIQUE constraints, which is not required in the ANSI/ISO standard. It also supports >REPLACE INTO syntax, [6] which first attempts an insert, and if that fails ...