A SELECT statement in SQL returns a result set of records from one or more tables. Wikibooks has more about this subject: SQL Structured Query Language (SQL) is the most popular computer language used to create, modify and retrieve data from relational database management systems. ... An SQL result set is a set of rows from a database, as well as meta-information about the query such as number of results returned and the column names. ...

It is used to retrieve zero or more rows from one or more tables in a database. In most applications, SELECT is the most commonly used Data Manipulation Language (DML) command. In specifying a SELECT query, the user specifies a description of the desired result set, but they do not specify what physical operations must be executed to produce that result set. Translating the query into an optimal "query plan" is left to the database system, more specifically to the query optimiser. Data Manipulation Language (DML): is a family of computer languages used by computer programs or database users to retrieve, insert, delete and update data in a database. ...

Commonly available keywords related to SELECT include:

• WHERE – used to identify which rows to be retrieved, or applied to GROUP BY.
• GROUP BY – used to combine rows with related values into elements of a smaller set of rows.
• HAVING – used to identify which rows, following a GROUP BY, are to be retrieved.
• ORDER BY – used to identify which columns are used to sort the resulting data.

Examples

Given a table T, the query SELECT * FROM T; will result in all the elements of all the rows of the table being shown.

With the same table, the query SELECT C1 FROM T; will result in the elements from the column C1 of all the rows of the table being shown — in Relational algebra terms, a projection will be performed. The relational algebra is a set of operations that manipulate relations as they are defined in the relational model and as such describes part of the data manipulation aspect of this data model. ...

With the same table, the query SELECT * FROM T WHERE C1 = 1; will result in all the elements of all the rows where the value of column C1 is '1' being shown — in Relational algebra terms, a selection will be performed, because of the WHERE keyword. The relational algebra is a set of operations that manipulate relations as they are defined in the relational model and as such describes part of the data manipulation aspect of this data model. ...

See also

• SQL
• Join (SQL)
• Insert (SQL)