6

Is it possible to pass in the name of a table into a stored procedure?

For example, suppose you have several views of the same table. They all have the exact same structure.

You want a stored procedure that can be run for any of the views.

Something like:

create procedure myprocedure
@tableName varchar(50) = ''
select blah from @tableName where blah = blah2 

When I try to do this, I get

Must declare the table variable @tablename

Any ideas how I can do this?

11

Instead of creating views, why not make an inline table-valued function - effectively a parameterized view. You basically get all the benefits of views AND parameters.

Another thing you can do in your TVF is something like this:

SELECT yourtable.*
FROM yourtable
INNER JOIN ranges
    ON yourtable.date BETWEEN ranges.start AND ranges.end
WHERE ranges.name = @range_name

Now your ranges have names (in a table where they can be easily managed without changing the schema) - this also fairly seamlessly handles multiple ranges with the same name, although if ranges overlap you can have duplicates due to the join matching both.

Also, please consider avoiding BETWEEN:

I strongly suggest that you reconsider your requirements and when asking questions here be sure to include more about your motivations, because when you bring in a question with a preconceived notion of what the solution is, you are likely to get a suboptimal solution. (like the dynamic SQL solutions given aren't going to easily work for your OR case, but that information about the problem space is buried in a comment from you)

From: http://sqlfiddle.com/#!6/a628a/1

CREATE TABLE LogData (
  Id INT IDENTITY NOT NULL
  ,Dt DATETIME NOT NULL
  ,Data VARCHAR(max) NOT NULL
);

CREATE TABLE Ranges (
  Id INT IDENTITY NOT NULL
  ,Name VARCHAR(50) NOT NULL
  ,DtStart DATETIME NOT NULL
  ,DtEnd DATETIME NOT NULL
);

CREATE TABLE Groups (
  Id INT IDENTITY NOT NULL
  ,Name VARCHAR(50) NOT NULL
);

CREATE TABLE RangeGroups (
  RangeId INT NOT NULL
  ,GroupId INT NOT NULL
);

INSERT INTO LogData (Dt, Data)
VALUES ('2011-11-23 11:00', 'before thanksgiving day')
       ,('2011-11-24 11:00', 'on thanksgiving day')
       ,('2011-12-24 11:00', 'on christmas eve')
       ,('2011-12-25 11:00', 'on christmas day')
       ,('2012-11-21 11:00', 'before thanksgiving day')
       ,('2012-11-22 11:00', 'on thanksgiving day')
       ,('2012-12-24 11:00', 'on christmas eve')
       ,('2012-12-25 11:00', 'on christmas day');

INSERT INTO Ranges (Name, DtStart, DtEnd)
VALUES ('THANKSGIVING2011', '2011-11-24', '2011-11-25')
       ,('CHRISTMASEVE2011', '2011-12-24', '2011-12-25')
       ,('CHRISTMASDAY2011', '2011-12-25', '2011-12-26')
       ,('BOXINGDAY2011', '2011-12-26', '2011-12-27')
       ,('NEWYEARSEVE2011', '2011-12-31', '2012-01-01')
       ,('NEWYEARSDAY2012', '2012-01-01', '2012-01-02')
       ,('THANKSGIVING2012', '2012-11-22', '2012-11-23')
       ,('CHRISTMASEVE2012', '2012-12-24', '2012-12-25')
       ,('CHRISTMASDAY2012', '2012-12-25', '2012-12-26')
       ,('BOXINGDAY2012', '2012-12-26', '2012-12-27')
       ,('NEWYEARSEVE2012', '2012-12-31', '2013-01-01')
       ,('NEWYEARSDAY2013', '2013-01-01', '2013-01-02');

INSERT INTO Groups (Name)
VALUES ('HOLIDAYS2011')
       ,('HOLIDAYS2012')
       ,('ANYCHRISTMAS');

INSERT INTO RangeGroups (RangeId, GroupId)
SELECT Id, (SELECT Id FROM Groups WHERE Name = 'HOLIDAYS2011')
FROM Ranges WHERE Name LIKE '%2011';

INSERT INTO RangeGroups (RangeId, GroupId)
SELECT Id, (SELECT Id FROM Groups WHERE Name = 'HOLIDAYS2012')
FROM Ranges WHERE Name LIKE '%2012';

INSERT INTO RangeGroups (RangeId, GroupId)
SELECT Id, (SELECT Id FROM Groups WHERE Name = 'ANYCHRISTMAS')
FROM Ranges WHERE Name LIKE 'CHRISTMAS%';


CREATE FUNCTION dbo.JustDoIt(@GroupName VARCHAR(50))
RETURNS TABLE
RETURN (
SELECT LogData.*
FROM LogData
INNER JOIN Ranges ON LogData.Dt >= Ranges.DtStart
AND LogData.Dt < Ranges.DtEnd
INNER JOIN RangeGroups
ON RangeGroups.RangeId = Ranges.Id
INNER JOIN Groups
ON Groups.Id = RangeGroups.GroupId
AND Groups.Name = @GroupName
);

SELECT *
FROM dbo.JustDoIt('HOLIDAYS2011');

SELECT *
FROM dbo.JustDoIt('HOLIDAYS2012');

SELECT *
FROM dbo.JustDoIt('ANYCHRISTMAS');

This part:

SELECT LogData.*
FROM LogData
INNER JOIN Ranges ON LogData.Dt >= Ranges.DtStart
AND LogData.Dt < Ranges.DtEnd
INNER JOIN RangeGroups
ON RangeGroups.RangeId = Ranges.Id
INNER JOIN Groups
ON Groups.Id = RangeGroups.GroupId
AND Groups.Name = @GroupName

Means that each log item will be joined to the ranges it fits in (by date), each range will join to the groups they are in, but only that group selected will be used.

  • @Cade Roux can you elaborate on the idea of a table with date ranges? What happens if one set of ranges contains 4 begin / end dates and another 5? Should each column be a datetime or what? Many thanks. – dublintech Jun 20 '12 at 16:30
  • 1
    @dublintech sqlfiddle.com/#!6/425db/1 – Cade Roux Jun 20 '12 at 17:09
  • 1
    @dublintech that example not only gives names to the ranges but also groups them. I did not restrict range to be unique, so you could have multiple Ranges with the same name and same group. You can see the power you now have by having this in a table - you can now do all kinds of interesting stuff with ranges. – Cade Roux Jun 20 '12 at 17:11
10

Object names cannot be parameterized.

You need to use dynamic SQL:

CREATE PROCEDURE MyProc
(
    @schemaName sysname,
    @tableName sysname,
    @blah2 int
)
AS
BEGIN

    SET NOCOUNT ON

    DECLARE @sql nvarchar(MAX)

    SET @sql = N'SELECT blah FROM '
        + QUOTENAME(@schemaName) + N'.' + QUOTENAME(@tableName) + N' WHERE blah = @blah2'

    EXEC sp_executesql @sql, N'@blah2 int', @blah2

END

Note that sysname is (currently) defined as nvarchar(128).

5

I think your best bet is to use dynamic SQL to accomplish this:

create procedure myprocedure
@tableName nvarchar(50) = ''
as

    declare @sql_cmd nvarchar(200) 
    set @sql_cmd = 'select blah from ' + QUOTENAME(@tableName) + ' where blah = blah2'

    exec (@sql_cmd)

go
-2

This code works in C# + SQL Server 2008

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

ALTER procedure [dbo].[test](@table_name varchar(max))
AS
BEGIN
    declare @tablename varchar(max)=@table_name;
    declare @statement varchar(max);

    set @statement = 'Select * from ' + @tablename;

    execute (@statement);
END
  • 1
    This leaves you wide open for SQL-injection. Please have a look at how it is done in the other answers. – Mikael Eriksson Feb 3 '15 at 8:13

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