Francisco H Tapia
my.lists at verizon.net
Thu Jun 10 15:55:25 CDT 2004
Andy, SQL Server is not Access on steriods, it's a diffrent engine, and thus requires a new level of thinking towards your database engine. It's NOT that you couldn't, you can do anything, heck if you wanted to you can set up your SQL Server with a blank SA password or SA as the password. For all that matters, and avoiding all SQL Server authentication, just use NT authentication and enable guest users :). There have been quite a few white papers circulating on why you "wouldn't" use dynamic sql w/ your sql server (check out www.sqlservercentral.com, a fine resource) but the 2 very critical factors include performance and also quite possible damage to your data. It is entirely possible for your sql statement to read in this manner, lets's say that you are Selecting Data from a table and you have a combobox to help choose data, so your SQL Statment looks like this: "Select CompanyName, CompanyAttribute1, pKey FROM tblCompany WHERE CompanyAttribute1 = '" & me.cboMyBOX & "'", If I was a malicious user on your system and I have direct access to tables, and if you're doing statements like the above it is entirely plausible that you also have "INSERT" statements thus you are giving more than just simple SELECT access to these tables., thus with some malformed selection I can add this in the select '; DELETE FROM tblCompany; SELECT ' your final statement would look like this Select CompanyName, CompanyAttribute1, pKey FROM tblCompany WHERE CompanyAttribute1 = ''; DELETE FROM tblCompany; SELECT '' Now your entire COMPANY table has been wiped out, while it is completely possible to restore your db up to the minute, you've still lost some downtime given that you had ONE bad apple in the bunch. Besides the sql injection threats, you also suffer from a NON-pre-compiled statement, thus your data could conceptually be returned a lot faster if you let it, simply by creating a view or stored procedure. By the way just because you are using a stored procedure does not make you completly excempt of sql injections, if you are using dynamic sql within that procedure you are still open to these kind of attacks and your stored procedure is always re-comiled and thus suffers from the same performance deficits. Andy Lacey wrote On 6/10/2004 1:27 PM: >But, Francisco, if I was porting to SQL Server my Access app which builds >SELECT statements dynamically all of the time for many and various >situations are you saying I couldn't, or shouldn't or something? > >-- Andy Lacey >http://www.minstersystems.co.uk > > > >>-----Original Message----- >>From: dba-sqlserver-bounces at databaseadvisors.com >>[mailto:dba-sqlserver-bounces at databaseadvisors.com] On Behalf >>Of Francisco H Tapia >>Sent: 10 June 2004 20:58 >>To: dba-sqlserver at databaseadvisors.com >>Subject: Re: [dba-SQLServer] Difference between views and queries >> >> >>jwcolby wrote On 6/10/2004 9:33 AM: >> >> >> >>>Can anyone explain the difference between a view and a query? Views >>>use a query, plus the view keyword. I have a couple of books that I >>>have read the chapter on Views, but I so far haven't managed >>> >>> >>to "get" >> >> >>>why you wouldn't just use the query itself instead of >>> >>> >>turning it into a >> >> >>>view. >>> >>> >>> >>> >>A query is a request for an Access Database, however for Sql >>Server you >>would either use a View or Stored Procedure to return the data you >>wanted... you are also able to use dynamic SQL to retrieve the >>information you need. ANY request given to the SQL Server engine is >>managed by the engine, unless you are running Remote servers (iirc). >> >>In Sql Server, it is TABOO, nay, GENERALLY bad practice to >>use dynamic >>sql because of the implication of SQL INJECTION attacks, this poses a >>"real" security threat to your database. and your server. >> >>another reason to use a VIEW over dynamic sql is that it is >>pre-optimized by the SQL Server Engine and thus runs faster and more >>efficient. Additionally if you use Dynamic SQL then your individual >>users who access the server will need EXPLICIT "SELECT" >>permissions by >>you, which is another 'bad' practice. In SQL Server you make data >>available to your users via VIEWs and Stored Procedures or some other >>secure way in order to protect your tables and it's data. >> >>ya get wot I mean? >> >>-- >>-Francisco >> >> >>_______________________________________________ >>dba-SQLServer mailing list >>dba-SQLServer at databaseadvisors.com >>http://databaseadvisors.com/mailman/listinfo/dba-sqlserver >>http://www.databaseadvisors.com >> >> >> >> >> > >_______________________________________________ >dba-SQLServer mailing list >dba-SQLServer at databaseadvisors.com >http://databaseadvisors.com/mailman/listinfo/dba-sqlserver >http://www.databaseadvisors.com > > > > -- -Francisco