Export (0) Print
Expand All
ABS
ALL
AND
ANY
AVG
bit
COS
COT
DAY
EXP
GO
IN
LEN
LOG
MAX
MIN
NOT
OR
PI
SET
SIN
STR
SUM
TAN
USE
VAR
Expand Minimize

DECLARE @local_variable

SQL Server 2000

Variables are declared in the body of a batch or procedure with the DECLARE statement and are assigned values with either a SET or SELECT statement. Cursor variables can be declared with this statement and used with other cursor-related statements. After declaration, all variables are initialized as NULL.

Syntax

DECLARE
    {{ @local_variable [AS] data_type }
        | { @cursor_variable_name CURSOR }
        | { table_type_definition }
    } [ ,...n]

< table_type_definition > ::=
    TABLE ( { < column_definition > | < table_constraint > } [ ,... ]
            )

< column_definition > ::=
    column_name scalar_data_type
    [ COLLATE collation_name ]
    [ [ DEFAULT constant_expression ] | IDENTITY [ ( seed, increment ) ] ]
    [ ROWGUIDCOL ]
    [ < column_constraint > ]

< column_constraint > ::=
    { [ NULL | NOT NULL ]
    | [ PRIMARY KEY | UNIQUE ]
    | CHECK ( logical_expression )
    }

< table_constraint > ::=
    { { PRIMARY KEY | UNIQUE } ( column_name [ ,... ] )
    | CHECK ( search_condition )
    }

Arguments

@local_variable

Is the name of a variable. Variable names must begin with an at sign (@). Local variable names must conform to the rules for identifiers. For more information, see Using Identifiers.

data_type

Is any system-supplied or user-defined data type. A variable cannot be of text, ntext, or image data type. For more information about system data types, see Data Types. For more information about user-defined data types, see sp_addtype.

@cursor_variable_name

Is the name of a cursor variable. Cursor variable names must begin with an at sign (@) and conform to the rules for identifiers.

CURSOR

Specifies that the variable is a local, cursor variable.

table_type_definition

Defines the table data type. The table declaration includes column definitions, names, data types, and constraints. The only constraint types allowed are PRIMARY KEY, UNIQUE, NULL, and CHECK. A user-defined data type cannot be used as a column scalar data type.

table_type_definition is a subset of information used to define a table in CREATE TABLE. Elements and essential definitions are included here; for more information, see CREATE TABLE.

n

Is a placeholder indicating that multiple variables can be specified and assigned values. When declaring table variables, the table variable must be the only variable being declared in the DECLARE statement.

column_name

Is the name of the column in the table.

scalar_data_type

Specifies that the column is a scalar data type.

[COLLATE collation_name]

Specifies the collation for the column. collation_name can be either a Windows collation name or an SQL collation name, and is applicable only for columns of the char, varchar, text, nchar, nvarchar, and ntext data types. If not specified, the column is assigned either the collation of the user-defined data type (if the column is of a user-defined data type), or the default collation of the database.

For more information about the Windows and SQL collation names, see COLLATE.

DEFAULT

Specifies the value provided for the column when a value is not explicitly supplied during an insert. DEFAULT definitions can be applied to any columns except those defined as timestamp, or those with the IDENTITY property. DEFAULT definitions are removed when the table is dropped. Only a constant value, such as a character string; a system function, such as a SYSTEM_USER(); or NULL can be used as a default. To maintain compatibility with earlier versions of SQL Server, a constraint name can be assigned to a DEFAULT.

constant_expression

Is a constant, NULL, or a system function used as the default value for the column.

IDENTITY

Indicates that the new column is an identity column. When a new row is added to the table, SQL Server provides a unique, incremental value for the column. Identity columns are commonly used in conjunction with PRIMARY KEY constraints to serve as the unique row identifier for the table. The IDENTITY property can be assigned to tinyint, smallint, int, decimal(p,0), or numeric(p,0) columns. Only one identity column can be created per table. Bound defaults and DEFAULT constraints cannot be used with an identity column. You must specify both the seed and increment, or neither. If neither is specified, the default is (1,1).

seed

Is the value used for the very first row loaded into the table.

increment

Is the incremental value added to the identity value of the previous row that was loaded.

ROWGUIDCOL

Indicates that the new column is a row global unique identifier column. Only one uniqueidentifier column per table can be designated as the ROWGUIDCOL column. The ROWGUIDCOL property can be assigned only to a uniqueidentifier column.

NULL | NOT NULL

Are keywords that determine whether or not null values are allowed in the column.

PRIMARY KEY

Is a constraint that enforces entity integrity for a given column or columns through a unique index. Only one PRIMARY KEY constraint can be created per table.

UNIQUE

Is a constraint that provides entity integrity for a given column or columns through a unique index. A table can have multiple UNIQUE constraints.

CHECK

Is a constraint that enforces domain integrity by limiting the possible values that can be entered into a column or columns.

logical_expression

Is a logical expression that returns TRUE or FALSE.

Remarks

Variables are often used in a batch or procedure as counters for WHILE, LOOP, or for an IF...ELSE block.

Variables can be used only in expressions, not in place of object names or keywords. To construct dynamic SQL statements, use EXECUTE.

The scope of a local variable is the batch, stored procedure, or statement block in which it is declared. For more information about using local variables in statement blocks, see Using BEGIN...END.

A cursor variable that currently has a cursor assigned to it can be referenced as a source in a:

  • CLOSE statement.

  • DEALLOCATE statement.

  • FETCH statement.

  • OPEN statement.

  • Positioned DELETE or UPDATE statement.

  • SET CURSOR variable statement (on the right side).

In all these statements, Microsoft® SQL Server™ raises an error if a referenced cursor variable exists but does not have a cursor currently allocated to it. If a referenced cursor variable does not exist, SQL Server raises the same error raised for an undeclared variable of another type.

Cursor variable values do not change after a cursor is declared. In SQL Server version 6.5 and earlier, variable values are refreshed every time a cursor is reopened.

A cursor variable:

  • Can be the target of either a cursor type or another cursor variable. For more information, see SET @local_variable.

  • Can be referenced as the target of an output cursor parameter in an EXECUTE statement if the cursor variable does not have a cursor currently assigned to it.

  • Should be regarded as a pointer to the cursor. For more information about cursor variables, see Transact-SQL Cursors.
Examples
A. Use DECLARE

This example uses a local variable named @find to retrieve author information for all authors with last names beginning with Ring.

USE pubs
DECLARE @find varchar(30)
SET @find = 'Ring%'
SELECT au_lname, au_fname, phone
FROM authors
WHERE au_lname LIKE @find

Here is the result set:

au_lname                               au_fname             phone        
-------------------------------------- -------------------- ------------ 
Ringer                                 Anne                 801 826-0752 
Ringer                                 Albert               801 826-0752 

(2 row(s) affected)
B. Use DECLARE with two variables

This example retrieves employee names from employees of Binnet & Hardley (pub_id = 0877) who were hired on or after January 1, 1993.

USE pubs
SET NOCOUNT ON
GO
DECLARE @pub_id char(4), @hire_date datetime
SET @pub_id = '0877'
SET @hire_date = '1/01/93'
-- Here is the SELECT statement syntax to assign values to two local 
-- variables.
-- SELECT @pub_id = '0877', @hire_date = '1/01/93'
SET NOCOUNT OFF
SELECT fname, lname
FROM employee
WHERE pub_id = @pub_id and hire_date >= @hire_date

Here is the result set:

fname                lname                          
-------------------- ------------------------------ 
Anabela              Domingues                      
Paul                 Henriot                        

(2 row(s) affected)

See Also

EXECUTE

Functions

SELECT

table

Was this page helpful?
(1500 characters remaining)
Thank you for your feedback
Show:
© 2014 Microsoft