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Displaying posts with tag: VFP (reset)

Keeping save – Injection attacks etc.
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I had someone point out to me that some of the sample code I have used might be vulnerable to an insertion attack. So I feel it is time to address this subject.

First when using examples I try to just focus on the subject of the current blog and often strip a lot of things that are irrelevant to the point I am trying to make out. But now to the subject of keeping your code save.

If you write and SQL statement looking something like

lc_sql = “SELECT * from customer WHERE custno = ‘” + lc_custno + “‘”

Someone could enter “‘; TRUNCATE TABLE customer;’” resulting in  a SQL statement looking like

SELECT * from customer WHERE custno = ”; TRUNCATE TABLE customer; ”

Which could be quite disasterous. So to avoid this we could use parameterized queries which I cannot as I am using a seperate function to

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Converting and optimizing SQL Statements
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Now it became time to conveert some SQL statements. Even though many SELECT SQL statements will run unchanged in MYSQL it might be wise to check and see if they are performing well. There are some differences in how VFP and MYSQL optimize queries and a query that just performs great in VFP might be very slow in MYSQL. And then there are some cases where we have to replace things that are possible in VFP but not supported in MYSQL.

First lets assume that our tables all have lots of records. After all it does not pay to spend time on optimizing on tables with a few dozend records. I also will not go into VFP optimization here as this is a MYSQL blog.

Lets assume for our first case we might have a table with invoice detail records and a table with items that are on sale. So now we want to get maybe 2 queries. One to show a total of all the items that were on sale and the second a total of all the

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Transferring VFP Table Structures to MYSQL
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So now that we have established some decent contact between VFP and MYSQL it is time to transfer as much as possible from the VFP Database into the MYSQL Schema. Being a long time believer that making a plan can keep you out of trouble I laid out the following steps for that task

  • Transfer Table Structures
  • Set up Indexes
  • Set up foreign keys

So lets look at each step more closely

Transfer Table Structures

Granted we could sit down and take a printout of all the structures and then use Workbench or something like it and start setting up the tables. But being faced with having to do that with close to 100 tables some of which having 40 or so fields this appeared like a daunting task. So I took a look to see how much could be optimized. Tables In MYSQL are created by using the CREATE TABLE ….. syntax which is pretty straight forward.

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Outgrowing Visual Foxpro
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Visual Foxpro was a platform of choice for small and medium applications for decades. I started writing things in Foxpro when it did not belong to Microsoft yet. I believe when it was in version 2.0. In a time when there was no Windows and machines had less than 1 Mb of Ram and a 80 MB harddisk was big. Back then the concern was to keep program and data small. After all those 80 Mb on your Novell Server had to last for a few years. I had a customer back then using SBT and entering about 300 invoices/day with about 15 lines per invoice on average and back then we used about 15 MB a year to store that information…..

Fast Forward to 2010. Said customer still does those 300 invoices on average a day, SBT is long gone, but the software has grown, been updated, improved, Moved to VFP9.0. Many features added, much more information stored. Now those 300 invoices/day run up close to 2 Gb of hard disk space a

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Showing entries 1 to 4

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