Monthly Archives: December 2011

  Relational Operations   A relational operation involves manipulating one or more tables, or relations, to result in another table. The three kinds of relational operations are selection,projection, and join. This chapter includes examples of selection, projection,and simple joining. Selection … Continue reading →

SELECT STATEMENT –  Continued  In a ISQL select statement only SELECT and FROM statements are mandatory. Other clauses like WHERE,GROUP BY,HAVING,ORDER BY are optional.     How to use expressions in ISQL SELECT Statement? Expressions combine many arithmetic operators, they can … Continue reading →

ISQL commands are instructions used to communicate with the database to perform specific task that work with data.  Normally SQL commands are grouped into four major categories depending on their functionality: Data Definition Language (DDL) – These SQL commands are … Continue reading →

INFORMIX-SQL Informix-SQL is the relational database management system that developers choose to create custom applications. Based on RDSQL,Informix SQL has the tools to create create  and maintain databases,design custom screens and menus and produce custom formatted reports. It also provides … Continue reading →

Reports Getting information out of the database and formatting it for printing remains a central purpose for most database applications. One of the reports in the demonstration application creates mailing labels for selected customer rows.That have been ordered by zip … Continue reading →

Query  BY Example There are several places in the complete application where the user must select a particular customer. Since it is not known in advance what criteria the user might have for selection, the code provides a function query_customer … Continue reading →

The  Statehelp  Function   The statehelp function tests whether the entry in the State field is valid.The function is Calculated automatically after the user moves the cursor out of the State field :- FUNCTION statehelp() Select  count(*)  into  idx from … Continue reading →

I ENTERING DATA USING A SCREEN FORM After creating a screen form, you will want to write the INFORMIX 4GL code to extract data from the screen and insert it into your database. The following program can do this job:- … Continue reading →

INFORMIX 4GL EXAMPLE APPLICATION   The quickest way to learn about the ease of programming with INFORMIX-4GL is  to read through program excerpts that produce some of the effects that were described earlier. Assume that you have been hired by … Continue reading →