SELECT (Transact-SQL)
Retrieves rows from the database and enables the selection of one or many rows or columns from one or many tables in SQL Server 2008 R2. The full syntax of the SELECT statement is complex, but the main clauses can be summarized as:
[ WITH <common_table_expression>]
SELECT select_list [ INTO new_table ]
[ FROM table_source ] [ WHERE search_condition ]
[ GROUP BY group_by_expression ]
[ HAVING search_condition ]
[ ORDER BY order_expression [ ASC | DESC ] ]
The UNION, EXCEPT and INTERSECT operators can be used between queries to combine or compare their results into one result set.
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Syntax
<SELECT statement> ::=
[WITH <common_table_expression> [,...n]]
<query_expression>
[ ORDER BY { order_by_expression | column_position [ ASC | DESC ] }
[ ,...n ] ]
[ COMPUTE
{ { AVG | COUNT | MAX | MIN | SUM } (expression )} [ ,...n ]
[ BY expression [ ,...n ] ]
]
[ <FOR Clause>]
[ OPTION ( <query_hint> [ ,...n ] ) ]
<query_expression> ::=
{ <query_specification> | ( <query_expression> ) }
[ { UNION [ ALL ] | EXCEPT | INTERSECT }
<query_specification> | ( <query_expression> ) [...n ] ]
<query_specification> ::=
SELECT [ ALL | DISTINCT ]
[TOP ( expression ) [PERCENT] [ WITH TIES ] ]
< select_list >
[ INTO new_table ]
[ FROM { <table_source> } [ ,...n ] ]
[ WHERE <search_condition> ]
[ <GROUP BY> ]
[ HAVING < search_condition > ]
Remarks
Because of the complexity of the SELECT statement, detailed syntax elements and arguments are shown by clause:
The order of the clauses in the SELECT statement is significant. Any one of the optional clauses can be omitted, but when the optional clauses are used, they must appear in the appropriate order.
SELECT statements are permitted in user-defined functions only if the select lists of these statements contain expressions that assign values to variables that are local to the functions.
A four-part name constructed with the OPENDATASOURCE function as the server-name part can be used as a table source wherever a table name can appear in a SELECT statement.
Some syntax restrictions apply to SELECT statements that involve remote tables. For more information, see Guidelines for Using Distributed Queries.
Logical Processing Order of the SELECT statement
The following steps show the logical processing order, or binding order, for a SELECT statement. This order determines when the objects defined in one step are made available to the clauses in subsequent steps. For example, if the query processor can bind to (access) the tables or views defined in the FROM clause, these objects and their columns are made available to all subsequent steps. Conversely, because the SELECT clause is step 8, any column aliases or derived columns defined in that clause cannot be referenced by preceding clauses. However, they can be referenced by subsequent clauses such as the ORDER BY clause. Note that the actual physical execution of the statement is determined by the query processor and the order may vary from this list.
FROM
ON
JOIN
WHERE
GROUP BY
WITH CUBE or WITH ROLLUP
HAVING
SELECT
DISTINCT
ORDER BY
TOP
Permissions
Selecting data requires SELECT permission on the table or view, which could be inherited from a higher scope such as SELECT permission on the schema or CONTROL permission on the table. Or requires membership in the db_datareader or db_owner fixed database roles, or the sysadmin fixed server role. Creating a new table using SELECTINTO also requires both the CREATETABLE permission, and the ALTERSCHEMA permission on the schema that owns the new table.