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SELECT clause (Transact-SQL)

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance SQL analytics endpoint in Microsoft Fabric Warehouse in Microsoft Fabric SQL database in Microsoft Fabric

Specifies the columns that the Transact-SQL (T-SQL) query returns.

Transact-SQL syntax conventions

Syntax

SELECT [ ALL | DISTINCT ]
[ TOP ( expression ) [ PERCENT ] [ WITH TIES ] ]
<select_list>
<select_list> ::=
    {
      *
      | { table_name | view_name | table_alias } .*
      | {
          [ { table_name | view_name | table_alias } . ]
               { column_name | $IDENTITY | $ROWGUID }
          | udt_column_name [ { . | :: } { { property_name | field_name }
            | method_name ( argument [ , ...n ] ) } ]
          | expression
         }
        [ [ AS ] column_alias ]
      | column_alias = expression
    } [ , ...n ]

Arguments

ALL

Specifies that duplicate rows can appear in the result set. ALL is the default.

DISTINCT

Specifies that only unique rows can appear in the result set. Null values are considered equal for the purposes of the DISTINCT keyword.

TOP (expression) [ PERCENT ] [ WITH TIES ]

Indicates that only a specified first set or percent of rows are returned from the query result set. expression can be either a number or a percent of the rows.

Although TOP <expression> without parentheses is supported in SELECT statements for backward compatibility, avoid this syntax. For more information, see TOP.

<select_list>

Specifies the columns to select for the result set. The select list is a series of expressions separated by commas. The maximum number of expressions that you can specify in the select list is 4,096.

*

Specifies that all columns from all tables and views in the FROM clause should be returned. The columns are returned by table or view, as specified in the FROM clause, and in the order in which they exist in the table or view.

table_name | view_name | table_alias.*

Limits the scope of the * to the specified table or view.

column_name

The name of a column to return. Qualify column_name to prevent an ambiguous reference, such as occurs when two tables in the FROM clause have columns with duplicate names. For example, the SalesOrderHeader and SalesOrderDetail tables in the AdventureWorks2025 database both have a column named ModifiedDate. If the two tables are joined in a query, you can specify the modified date of the SalesOrderDetail entries in the select list as SalesOrderDetail.ModifiedDate.

expression

A constant, function, any combination of column names, constants, and functions connected by an operator or operators, or a subquery.

$IDENTITY

Returns the identity column. For more information, see IDENTITY (Property), ALTER TABLE, and CREATE TABLE.

If more than one table in the FROM clause has a column with the IDENTITY property, you must qualify $IDENTITY with the specific table name, such as T1.$IDENTITY.

$ROWGUID

Returns the row GUID column.

If more than one table in the FROM clause has the ROWGUIDCOL property, you must qualify $ROWGUID with the specific table name, such as T1.$ROWGUID.

udt_column_name

The name of a common language runtime (CLR) user-defined type column to return.

Note

SQL Server Management Studio returns user-defined type values in binary representation. To return user-defined type values in string or XML format, use CAST and CONVERT or CAST and CONVERT.

{ . | :: }

Specifies a method, property, or field of a CLR user-defined type. Use a period (.) for an instance (nonstatic) method, property, or field. Use a double-colon (::) for a static method, property, or field. To invoke a method, property, or field of a CLR user-defined type, you must have EXECUTE permission on the type.

property_name

A public property of udt_column_name.

field_name

A public data member of udt_column_name.

method_name

A public method of udt_column_name that takes one or more arguments. method_name can't be a mutator method.

The following example selects the values for the Location column, defined as type point, from the Cities table, by invoking a method of the type called Distance:

CREATE TABLE dbo.Cities
(
    Name VARCHAR (20),
    State VARCHAR (20),
    Location POINT
);
GO

DECLARE @p AS POINT (32, 23),
        @distance AS FLOAT;

SELECT Location.Distance(@p)
FROM Cities;

column_alias

An alternative name to replace the column name in the query result set. For example, an alias such as Quantity, or Quantity to Date, or Qty can be specified for a column named quantity.

You can use aliases to specify names for the results of expressions, for example:

USE AdventureWorks2025;
GO

SELECT AVG(UnitPrice) AS [Average Price]
FROM Sales.SalesOrderDetail;

column_alias can be used in an ORDER BY clause. However, you can't use it in a WHERE, GROUP BY, or HAVING clause. If the query expression is part of a DECLARE CURSOR statement, column_alias can't be used in the FOR UPDATE clause.

Remarks

When you include text or ntext columns in the select list, the length of the returned data is the smallest value of the following options:

  • the actual size of the text column,
  • the default TEXTSIZE session setting, or
  • the hard-coded application limit.

To change the length of returned text for the session, use the SET statement. By default, the limit on the length of text data returned by a SELECT statement is 4,000 bytes.

The SQL Server Database Engine raises exception 511 and rolls back the current running statement if either of the following behaviors occurs:

  • The SELECT statement produces a result row or an intermediate work table row that exceeds 8,060 bytes.

  • The DELETE, INSERT, or UPDATE statement tries an action on a row that exceeds 8,060 bytes.

An error occurs if you don't specify a column name for a column created by a SELECT INTO or CREATE VIEW statement.

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