I want to create a procedure that can execute any select in database and has table name and column names and where clause as input parameters
how can I develop that?
As an exam exercise, it's ok, but never do something like this in a real environment because of the SQL Injection danger.
CREATE PROCEDURE QueryExecution (
#columns varchar(200),
#tableName varchar(50),
#conditions varchar(200))
AS
BEGIN
declare #query nvarchar(max);
set #query = 'SELECT ' + #columns + ' FROM ' + #tableName + ' WHERE ' + #conditions
exec sp_executesql #query
END
Then call it like this:
exec QueryExecution 'Id, Description', 'MyTable', 'Id > 5 AND Description LIKE ''%some text%'''
Note: if you need single quotes in your string, you must escape them by doubling them, like you can see in the LIKE clause.
Related
Is there a way to do something like this? People is the name of the table.
declare #placeholder varchar(20) = 'People'
select * from #placeholder
Or something like this where the table name is People_Backup.
declare #placeholder varchar(20) = '_Backup'
select * from People#placeholder
And is there a way to add in dynamic sql the value of a variable?
something like this:
declare #placeholder nvarchar(20) = 'people'
declare #name nvarchar(30) = 'antony'
declare #query nvarchar(1000) = 'select * from ' + #placeholder + ' where
first_name=' + #name
exec sp_executesql #query
I mean: without do this
exec sp_executesql #query, N'#name varchar(30)', #name
Thank you for the answers.
Not without dynamic SQL.
Parameters in SQL are placeholders for data, and can't be used as placeholders for anything else (which includes commands such as select, update etc' and identifiers such as database name, schema name, table name, column name etc').
The only way to parameterize table names is to use dynamic SQL - meaning you must build a string containing the SQL you want to execute, and then execute it.
Beware - dynamic SQL might be an open door for SQL injection attacks - so you must do it wisely - here are some ground rules:
Always white-list your identifiers (using system tables or views such as sys.Tables or Information_schema.Columns)
Always use sysname as the datatype for identifiers.
The sysname data type is used for table columns, variables, and stored procedure parameters that store object names. The exact definition of sysname is related to the rules for identifiers. Therefore, it can vary between instances of SQL Server.
Never pass SQL commands or clauses in parameters - set #placeholder = 'select a, b, c' or set #placeholder = 'where x = y' is a security hazard!
Always use parameters for data. Never concatenate parameters into your sql string: set #sql = 'select * from table where x = '+ #x is a security hazard. Always create your dynamic SQL to use parameters as parameters: set #sql = 'select * from table where x = #x'
Always use sp_executeSql to execute your dynamic SQL statement, not EXEC(#SQL).
For more information, read Kimberly Tripp's EXEC and sp_executesql – how are they different?
Always wrap identifiers with QUOTENAME() to ensure correct query even when identifiers include chars like white-spaces
To recap - a safe version of what you are asking for (with an additional dynamic where clause to illustrate the other points) is something like this:
#DECLARE #TableName sysname = 'People',
#ColumnName sysname = 'FirstName'
#Search varchar(10) = 'Zohar';
IF EXISTS(
SELECT 1
FROM Information_Schema.Columns
WHERE TABLE_NAME = #TableName
AND COLUMN_NAME = #ColumnName
)
BEGIN
DECLARE #Sql nvarchar(4000) =
'SELECT * FROM +' QUOTENAME(#TableName) +' WHERE '+ QUOTENAME(#ColumnName) +' LIKE ''%''+ #Search +''%'';'
EXEC sp_executesql #Sql, N'#Search varchar(10)', #Search
END
-- you might want to raise an error if not
To answer your question after edited directly:
I mean: without do this exec sp_executesql #query, N'#name varchar(30)', #name
Yes, you can do it without using sp_executeSql, but it's dangerous - it will enable an attacker to use something like '';DROP TABLE People;-- as the value of #name, so that when you execute the sql, your People table will be dropped.
To do that, you will need to wrap the #name with ' -
declare #placeholder nvarchar(20) = 'people'
declare #name nvarchar(30) = 'antony'
declare #query nvarchar(1000) = 'select * from ' + QUOTENAME(#placeholder) + ' where
first_name=''' + #name +''''
exec(#query)
I mean: without do this exec sp_executesql #query, N'#name varchar(30)', #name
Yes, you can do that as
--Use MAX instead of 1000
DECLARE #SQL nvarchar(MAX) = N'SELECT * FROM ' + #placeholder + ' WHERE first_name = '''+#name +'''';
EXECUTE sp_executesql #SQL;
create procedure sp_First
#columnname varchar
AS
begin
select #columnname from Table_1
end
exec sp_First 'sname'
My requirement is to pass column names as input parameters.
I tried like that but it gave wrong output.
So Help me
You can do this in a couple of ways.
One, is to build up the query yourself and execute it.
SET #sql = 'SELECT ' + #columnName + ' FROM yourTable'
sp_executesql #sql
If you opt for that method, be very certain to santise your input. Even if you know your application will only give 'real' column names, what if some-one finds a crack in your security and is able to execute the SP directly? Then they can execute just about anything they like. With dynamic SQL, always, always, validate the parameters.
Alternatively, you can write a CASE statement...
SELECT
CASE #columnName
WHEN 'Col1' THEN Col1
WHEN 'Col2' THEN Col2
ELSE NULL
END as selectedColumn
FROM
yourTable
This is a bit more long winded, but a whole lot more secure.
No. That would just select the parameter value. You would need to use dynamic sql.
In your procedure you would have the following:
DECLARE #sql nvarchar(max) = 'SELECT ' + #columnname + ' FROM Table_1';
exec sp_executesql #sql, N''
Try using dynamic SQL:
create procedure sp_First #columnname varchar
AS
begin
declare #sql nvarchar(4000);
set #sql='select ['+#columnname+'] from Table_1';
exec sp_executesql #sql
end
go
exec sp_First 'sname'
go
This is not possible. Either use dynamic SQL (dangerous) or a gigantic case expression (slow).
Create PROCEDURE USP_S_NameAvilability
(#Value VARCHAR(50)=null,
#TableName VARCHAR(50)=null,
#ColumnName VARCHAR(50)=null)
AS
BEGIN
DECLARE #cmd AS NVARCHAR(max)
SET #Value = ''''+#Value+ ''''
SET #cmd = N'SELECT * FROM ' + #TableName + ' WHERE ' + #ColumnName + ' = ' + #Value
EXEC(#cmd)
END
As i have tried one the answer, it is getting executed successfully but while running its not giving correct output, the above works well
You can pass the column name but you cannot use it in a sql statemnt like
Select #Columnname From Table
One could build a dynamic sql string and execute it like EXEC (#SQL)
For more information see this answer on dynamic sql.
Dynamic SQL Pros and Cons
As mentioned by MatBailie
This is much more safe since it is not a dynamic query and ther are lesser chances of sql injection . I Added one situation where you even want the where clause to be dynamic . XX YY are Columns names
CREATE PROCEDURE [dbo].[DASH_getTP_under_TP]
(
#fromColumnName varchar(10) ,
#toColumnName varchar(10) ,
#ID varchar(10)
)
as
begin
-- this is the column required for where clause
declare #colname varchar(50)
set #colname=case #fromUserType
when 'XX' then 'XX'
when 'YY' then 'YY'
end
select SelectedColumnId from (
select
case #toColumnName
when 'XX' then tablename.XX
when 'YY' then tablename.YY
end as SelectedColumnId,
From tablename
where
(case #fromUserType
when 'XX' then XX
when 'YY' then YY
end)= ISNULL(#ID , #colname)
) as tbl1 group by SelectedColumnId
end
First Run;
CREATE PROCEDURE sp_First #columnname NVARCHAR(128)--128 = SQL Server Maximum Column Name Length
AS
BEGIN
DECLARE #query NVARCHAR(MAX)
SET #query = 'SELECT ' + #columnname + ' FROM Table_1'
EXEC(#query)
END
Second Run;
EXEC sp_First 'COLUMN_Name'
Please Try with this.
I hope it will work for you.
Create Procedure Test
(
#Table VARCHAR(500),
#Column VARCHAR(100),
#Value VARCHAR(300)
)
AS
BEGIN
DECLARE #sql nvarchar(1000)
SET #sql = 'SELECT * FROM ' + #Table + ' WHERE ' + #Column + ' = ' + #Value
--SELECT #sql
exec (#sql)
END
-----execution----
/** Exec Test Products,IsDeposit,1 **/
I have 6 table with different fields. I want to access table name dynamically. is there any idea to do it?
My code is below this is simple procedure which I want to make dynamic to use in c#. how to do it?
Create procedure [dbo].[Insert_Data] (#Id int,#FeesHead nchar(20),#Fees int,#Remarks nchar(20))
as
begin
Insert into FeesHead(ID,FeesHead,Fees,Remarks)values(#Id,#FeesHead,#Fees,#Remarks)
End
Don't go there.
It's a bad idea since you will end up with a long, inefficient stored procedure that will be vulnerable to SQL injection attacks and have performance issues.
Writing an insert stored procedure for each table is the way to go.
You wrote you have six different tables with different columns, so writing a stored procedure to handle inserts for all of them will require you to send all the parameters for all columns as well as a parameter for the table name, and a nested if...else with 6 possible paths, one for each table.
This will end up as a long, messy, poorly written code at best, bad in each parameter: security, performance, code readability and maintainability.
The only way that makes some sense to achieve such a goal is to write individual insert stored procedures for each table, and then write a stored procedure that will take all of the possible parameters and the table name and inside of it decide what insert stored procedure to execute based on the value of the table name parameter. However, you will be better off leaving conditions like these to the SQL client (your c# code in this case) then to SQL Server.
Its very easy to do.........
Just call the sql query using Data Adapter.
select TABLE_NAME from INFORMATION_SCHEMA.TABLES
As you said you need dynamic SQL like this:
Create procedure [dbo].[Insert_Data]
(
#TableName nvarchar(512),
#Values nvarchar(max)
)
BEGIN
DECLARE #SQL nvarchar(max)
SELECT #SQL = 'INSERT INTO ' + #TableName + ' VALUES (' + #Values + ')'
EXEC(#SQL)
END
Note that #Values will be like this '1, ''name'', 10.2' and with the same order of columns.
or
Create procedure [dbo].[Insert_Data]
(
#TableName nvarchar(512),
#Fields nvarchar(max),
#Values nvarchar(max)
)
BEGIN
DECLARE #SQL nvarchar(max)
SELECT #SQL = 'INSERT INTO ' + #TableName + ' (' + #Fields + ') VALUES (' + #Values + ')'
EXEC(#SQL)
END
To more ability to handle column order and remove identity columns.
As Robert Harvey mentioned it is a bad idea, anyway if you want to you can do something like....
CREATE PROCEDURE Insert_Data
#TableName SYSNAME
,#Column1 SYSNAME = NULL
,#Column2 SYSNAME = NULL
,#Column3 SYSNAME = NULL
,#Value1 NVARCHAR(100) = NULL
,#Value2 NVARCHAR(100) = NULL
,#Value3 NVARCHAR(100) = NULL
AS
BEGIN
SET NOCOUNT ON;
DECLARE #Sql NVARCHAR(MAX);
SET #Sql = N' INSERT INTO ' + QUOTENAME(#TableName)
+ N' ( '
+ STUFF(
CASE WHEN #Column1 IS NOT NULL
THEN N',' + QUOTENAME(#Column1) ELSE N'' END
+ CASE WHEN #Column2 IS NOT NULL
THEN N',' + QUOTENAME(#Column2) ELSE N'' END
+ CASE WHEN #Column3 IS NOT NULL
THEN N',' + QUOTENAME(#Column3) ELSE N'' END
,1,1,'')
+ N' ) '
+ N' VALUES ( '
+ STUFF(
CASE WHEN #Value1 IS NOT NULL
THEN N', #Value1' ELSE N'' END
+ CASE WHEN #Value2 IS NOT NULL
THEN N', #Value2' ELSE N'' END
+ CASE WHEN #Value3 IS NOT NULL
THEN N', #Value3' ELSE N'' END
,1,1,'')
+ N' ) '
Exec sp_executesql #Sql
,N'#Value1 NVARCHAR(100),#Value2 NVARCHAR(100),#Value3 NVARCHAR(100)'
,#Value1
,#Value2
,#Value3
END
I am using SQL Server 2012, I am going to Create Store Procedure which copies a column from a table in a variable, Could any one please tell me what is Wrong with this code?
alter Procedure Id_Fetch
#Col varchar(50)=null,
#Table VARCHAR(50)=Null,
#OrdrBy Varchar(40)=null
as
Begin
declare #TempCol nvarchar (100)
Exec(' SELECT '+#TempCol+' = '+#Col+' from ' + #Table +' order by '+#OrdrBy )
its showing error "Incorrect Syntax near '='
A little modification ...... Use TOP 1 in your select as if more than one value is returned by your select it will throw an error.
Use SYSNAME datatype for your Column names and table names.
Use QUOTENAME() function around your object name parameters, which puts square brackets [] around the passed parameter value and forces it to be treated as an object name (Protection against Sql Injection attack).
Use sp_executesql instead of EXEC and concatenating parameter values into string and executing again protects you against Sql Injection attack.
ALTER PROCEDURE Id_Fetch
#Col SYSNAME,
#Table SYSNAME,
#OrdrBy SYSNAME,
#Col_Value NVARCHAR(100) OUTPUT
AS
BEGIN
SET NOCOUNT ON;
DECLARE #Sql NVARCHAR(MAX);
SET #Sql = N' SELECT TOP 1 #Col_Value = ' + QUOTENAME(#Col)
+ N' FROM ' + QUOTENAME(#Table)
+ N' ORDER BY ' + QUOTENAME(#OrdrBy)
EXECUTE sp_executesql #Sql
,N'#Col_Value NVARCHAR(100) OUTPUT'
,#Col_Value OUTPUT
END
I want to create a stored procedure with two parameters ColumnName and ColumnValue for searching
My query would look something like this:
SELECT * FROM TableName WHERE #ColumnName Like #ColumnValue + '%'
but it's return 0 result
You need Dynamic SQL for that. What you have written is searching the #columnValue value in the #ColumnName value. So if your column is foo and the value is bar it searches if 'foo' LIKE 'bar%'
DECLARE #SQL AS NVARCHAR(MAX)
SET #SQL =
N'SELECT * FROM TableName
WHERE ' + QuoteName(#ColumnName) + ' LIKE #val+''%'''
EXECUTE sp_executesql
#SQL,
N'#val varchar(100)',
#val = #ColumnValue;