Question

So, I haven’t had any luck finding any articles or forum posts that have explained to me how exactly a query language works in conjunction with a general use programming language like c++ or vb. So I guess it wont hurt to ask >.<

Basically, I’ve been having a hard time understanding what the roles of the query language are ( we’ll use SQL as an example for query language and VB6 for norm language) if i’m creating a simple database query that fills a table with normal information (first name, last name, address etc). I somewhat know the steps in setting up a program like this using ado objects for the connection and whatnot, but how do we decide which language of the 2 gets used for certain things ? Does vb6 specifically handle the basics like loops, if else’s, declarations of your vars, and SQL specifically handles things like connecting to the database and doing the searching, filtering and sorting ? Is it possible to do certain general use vb6 actions (loops or conditionals) in SQL syntax instead ? Any help would be GREATLY appreciated.

Answer 1

SQL is a language to query a database. SQL is an ISO standard and relational database vendors implement to the ISO standard and then add on their own customizations. For example in SQL Server it is called T-SQL and in Oracle it is called PL-SQL. They both implement ISO standards and so each will have identical queries for a simple select like

select columname from tablename where columnname=1

However, each have different syntax for string functions, date functions, etc….

The ISO SQL standard by design is not a full procedural language with looping, subroutines, ect as in a full procedural language like VB.

However, each vendor has added capabilities to their version to add some of this functionality in.

For example both T-SQL and PL-SQL can “loop” through records using various constructs in their language.

There is also a difference when working with data that many developers are not well in tuned with. That is set based operations vs. procedural based.

Databases can work with procedural constructs but are often more performant with set based. A developer who is not versed in this concept may end up creating a very innefficient query. Here’s an example of this discussion.

With any situation you have to weight out the pro’s/con’s of where it is best to do this work.

I tend to favor using procedural constructs such as loops in the language I am using over SQL. I find it easier to maintain and the language I am using offers more powerful syntax for me to get the job done.

However, I keep both options as a tool in the toolbox. For example, I have written data conversion scripts in SQL and in this case I have used the looping constructs in SQL.