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Running SQL Query from a SQL Query

I have a table where I want to run a query that I get from a query.
What I want to do is return the name (checkbooks, clients, etc) and the results of the sql queries per each type. all within one query result so I can send that data out. I have no clue where to start.

You could try using your first query to open a cursor, then within the loop execute the result string as dynamic SQL. I dont know what your tables or columns are called, but assuming table is called Table and column containing those Selects is Result, you could try something like:
declare commands cursor for
select result from table
declare #cmd varchar(max)
open commands
fetch next from commands into #cmd
while ##FETCH_STATUS=0
begin
exec(#cmd)
fetch next from commands into #cmd
end
close commands
deallocate commands
Inspired by this question:
execute result of select statement

This doesn't look like a good idea, unless there is no way for you to change this approach.
If you are using EF, after getting the row, you can execute the query in the query test field like this
context.MyEntity.SqlQuery("SELECT * FROM dbo.MyEntity").ToList();
https://learn.microsoft.com/en-us/ef/ef6/querying/raw-sql
You can do the same with different ORM, the idea is simple get the string in the field and pass it to the execute query.
FYI: Is saving SQL statements in a table for executing later a bad idea?
https://softwareengineering.stackexchange.com/questions/227922/is-saving-sql-statements-in-a-table-for-executing-later-a-bad-idea

Additional conditions when using LINQ to SQL updates

I am quite novice to LINQ, but I have the impression that when updating tables, LINQ creates some SQL code like this:
UPDATE table_name
SET column1=value1,column2=value2,...
WHERE some_column=some_value;
And I guess that the primary key is used within the WHERE clause. Let's suppose my tables/objects have a timestamp column and I want to check if the timestamp has changed since last time I read a particular row. I.e., my UPDATE statement would be:
UPDATE table_name
SET column1=value1,column2=value2,...
WHERE some_column=some_value AND timestamp=my_timestamp;
Obviously the purpose is to abort updates when the timestamp has changed (meaning that another user has updated this row and my data is outdated).
Does LINQ support something like this?

I recommend that you look into using the built in concurrency functionality for LINQ to SQL:
http://msdn.microsoft.com/en-us/library/bb399373%28v=vs.110%29.aspx
Read through that and then I'd bet that you're going to need to use this:
http://msdn.microsoft.com/en-us/library/system.data.linq.mapping.updatecheck%28v=vs.110%29.aspx

Is it possible to insert data in to table through coding with out using table name

My question is generally we write the following through code while we are inserting data to a table
insert into tblname values('"+txt.text+"','"+txt1.text+"');
As we pass the data form the text boxes like that is it possible to insert in to table with out using table name directlty

Well you obviously need to know what table to insert into, so there has to be a table name identified to the INSERT statement. The options include:
an INSERT statement with actual table name as per your existing example
an INSERT statement with a synonym as the target (alias for an actual table - see: http://blog.sqlauthority.com/2008/01/07/sql-server-2005-introduction-and-explanation-to-synonym-helpful-t-sql-feature-for-developer/)
an INSERT statement with an updateable view as the target
a sproc call whereby the sproc knows the table to INSERT into (but the calling code does not need to know)
You should also be aware of SQL injection risks with your example - avoid concatenating values directly into a SQL string to execute. Instead, parameterise the SQL.
If you need to dynamically specify the table to insert into at run time, you have to concatenate the table name into the SQL statement you then execute. However, be very wary of SQL injection - make sure you fully validate the tablename to make sure there are no nasties in it. You could even check it is a real table by checking for it in sys.tables.

Not possible without name of table.
But you can make use of Linq To SQL (i.e any ORM) or DataAdapter.Update if you have filled it with the proper table....

You cannot do that without the table name, no. However, the bigger problem is that your code is horribly dangerous and at rick from SQL injection. You should fix this right now, today, immediately. Injection, even for internal apps, is the single biggest risk. Better code would be:
insert into tblname (Foo, Bar) values(#foo, #bar)
adding the parameters #foo and #bar to your command (obviously, replace with sensible names).
Before you ask: no, the table name cannot be parameterised; you cannot use
insert into #tblname -- blah
The table name(s) is(/are) fundamental in any query or operation.

I suppose that if it's possible you have to use parameters.
Here you have a little example.

Is there any way to get the table hierarchy from a connection string in c#?

I have a current requirement to determine the table hierarchy from a sql statement within c#. For example, consider the following sql statement:
Select Table1.*, Table2.* from Table1
left join table2 on Table1.parentCol = Table2.childCol
That might return 7 columns, 3 for Table1 and 4 for table2. I need to know the column names, and ideally (though not mandatory) their types.
I have no control over what SQL Statement will be used, as this is a user entered field. In C# it's a very basic task to open a connection and create an SqlCommand using that statement. I have freedom to run the SQL into a SqlDataReader, or any other System.Data.SqlClient class if necessary, however I cannot find any combination that will return the columns, rather than the actual column values.
Is anyone able to help?
Many thanks and best regards

You cannot do what you are asking (easily).
More to the point, do not let users enter arbitrary TSQL (You will regret it at some point...).
Instead, create a 'Search' form that allows entering various params and use a parameterised query onto a view that joins all the tables/columns required.

There's no direct way. You'll need to parse names of all the tables from the sql query.
Once you have done that you'll need to write few queries on Information_Schema to get raw data for what you are looking for.
If you are on SQL Server, you may want to use Catalog View
ex-
Select * from sys.tables where [Name] = 'MyTable'

How do I protect this function from SQL injection?

public static bool TruncateTable(string dbAlias, string tableName)
{
string sqlStatement = string.Format("TRUNCATE TABLE {0}", tableName);
return ExecuteNonQuery(dbAlias, sqlStatement) > 0;
}

The most common recommendation to fight SQL injection is to use an SQL query parameter (several people on this thread have suggested it).
This is the wrong answer in this case. You can't use an SQL query parameter for a table name in a DDL statement.
SQL query parameters can be used only in place of a literal value in an SQL expression. This is standard in every implementation of SQL.
My recommendation for protecting against SQL injection when you have a table name is to validate the input string against a list of known table names.
You can get a list of valid table names from the INFORMATION_SCHEMA:
SELECT table_name
FROM INFORMATION_SCHEMA.Tables
WHERE table_type = 'BASE TABLE'
AND table_name = #tableName
Now you can pass your input variable to this query as an SQL parameter. If the query returns no rows, you know that the input is not valid to use as a table. If the query returns a row, it matched, so you have more assurance you can use it safely.
You could also validate the table name against a list of specific tables you define as okay for your app to truncate, as #John Buchanan suggests.
Even after validating that tableName exists as a table name in your RDBMS, I would also suggest delimiting the table name, just in case you use table names with spaces or special characters. In Microsoft SQL Server, the default identifier delimiters are square brackets:
string sqlStatement = string.Format("TRUNCATE TABLE [{0}]", tableName);
Now you're only at risk for SQL injection if tableName matches a real table, and you actually use square brackets in the names of your tables!

As far as I know, you can't use parameterized queries to perform DDL statements/ specify table names, at least not in Oracle or Sql Server. What I would do, if I had to have a crazy TruncateTable function, that had to be safe from sql injection would be to make a stored procedure that checks that the input is a table that is safe to truncate.
-- Sql Server specific!
CREATE TABLE TruncableTables (TableName varchar(50))
Insert into TruncableTables values ('MyTable')
go
CREATE PROCEDURE MyTrunc #tableName varchar(50)
AS
BEGIN
declare #IsValidTable int
declare #SqlString nvarchar(50)
select #IsValidTable = Count(*) from TruncableTables where TableName = #tableName
if #IsValidTable > 0
begin
select #SqlString = 'truncate table ' + #tableName
EXECUTE sp_executesql #SqlString
end
END

If you're allowing user-defined input to creep into this function via the tablename variable, I don't think SQL Injection is your only problem.
A better option would be to run this command via its own secure connection and give it no SELECT rights at all. All TRUNCATE needs to run is the ALTER TABLE permission. If you're on SQL 2005 upwards, you could also try using a stored procedure with EXECUTE AS inside.

CREATE OR REPLACE PROCEDURE truncate(ptbl_name IN VARCHAR2) IS
stmt VARCHAR2(100);
BEGIN
stmt := 'TRUNCATE TABLE '||DBMS_ASSERT.SIMPLE_SQL_NAME(ptbl_name);
dbms_output.put_line('<'||stmt||'>');
EXECUTE IMMEDIATE stmt;
END;

Use a stored procedure. Any decent db library (MS Enterprise Library is what I use) will handle escaping string parameters correctly.
Also, re:parameterized queries: I prefer to NOT have to redeploy my app to fix a db issue. Storing queries as literal strings in your source increases maintenance complexity.

Have a look at this link
Does this code prevent SQL injection?
Remove the unwanted from the tableName string.
I do not think you can use param query for a table name.

There are some other posts which will help with the SQL injection, so I'll upvote those, but another thing to consider is how you will be handling permissions for this. If you're granting users db+owner or db_ddladmin roles so that they can truncate tables then simply avoiding standard SQL injection attacks isn't sufficient. A hacker can send in other table names which might be valid, but which you wouldn't want truncated.
If you're giving ALTER TABLE permissions to the users on the specific tables that you will allow to be truncated then you're in a bit better shape, but it's still more than I like to allow in a normal environment.
Usually TRUNCATE TABLE isn't used in normal day-to-day application use. It's used for ETL scenarios or during database maintenance. The only situation where I might imagine it would be used in a front-facing application would be if you allowed users to load a table which is specific for that user for loading purposes, but even then I would probably use a different solution.
Of course, without knowing the specifics around why you're using it, I can't categorically say that you should redesign, but if I got a request for this as a DBA I'd be asking the developer a lot of questions.

Use parameterized queries.

In this concrete example you need protection from SQL injection only if table name comes from external source.
Why would you ever allow this to happen?
If you are allowing some external entity (end user, other system, what?)
to name a table to be dropped, why won't you just give them admin rights.
If you are creating and removing tables to provide some functionality for end user,
don't let them provide names for database objects directly.
Apart from SQL injection, you'll have problems with name clashes etc.
Instead generate real table names yourself (e.g DYNTABLE_00001, DYNTABLE_00002, ...) and keep a table that connects them to the names provided by user.
Some notes on generating dynamic SQL for DDL operations:
In most RDBMS-s you'll have to use dynamic SQL and insert table names as text.
Be extra careful.
Use quoted identifiers ([] in MS SQL Server, "" in all ANSI compliant RDBMS).
This will make avoiding errors caused by invalid names easier.
Do it in stored procedures and check if all referenced objects are valid.
Do not do anything irreversible. E.g. don't drop tables automatically.
You can flag them to be dropped and e-mail your DBA.
She'll drop them after the backup.
Avoid it if you can. If you can't, do what you can to minimize rights to other
(non-dynamic) tables that normal users will have.

You could use SQLParameter to pass in tableName value. As far as I know and tested, SQLParameter takes care of all parameter checking and thus disables possibility of injection.

If you can't use parameterized queries (and you should) ... a simple replace of all instances of ' with '' should work.
string sqlStatement = string.Format("TRUNCATE TABLE {0}", tableName.Replace("'", "''"));