Informix Training

INFORMIX-4GL TRAINING

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Versions of Informix-4GL »Informix-4GL Rapid Development System (RDS) »Informix-4GL C Compiler Version Compiling: Rapid Development System: Source file .4glPseudo code C Compiler System: Source .4gl->Intermediate fles->Executable file .4ge

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Differences b/w the two versions: RDS

C Compiler

» Compile Time

Less

More

» Run Time

More

Less

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Basic Components of Informix 4GL »PROGRAM »MODULE »FUNCTION »FORM

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Program Blocks »MAIN »FUNCTION »REPORT

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Compiling .4gl in RDS System »Creating a program from a single module fglpc filename.4gl »Creating a program from multiple modules Compile each program to p-code fglpc file1.4gl file2.4gl Concatenate p-code files together Cat file1.4go file2.4go >myprog.4gi »Executing the program fglgo filename.4go OR fglgo myprog.4gi | © Kanbay Incorporated. All Rights Reserved

Compiling .4gl in C Compiler version » Creating a program from a single module C4gl filename.4gl –o myprog.4ge » Creating a program from multiple modules To compile a singe module to object code C4gl filename.4gl –o filename.o To create an executable from multiple modules C4gl file1.4gl file2.o file3.0 –o myprog.4ge » Executing the program myprog.4ge

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Sample makefile 4GL = filename.4gl filename2.4gl FORM = formname.per PROG_NAME = application.4ge COBJS = $(4GL: .4gl=.o) POBJS = $(4GL:.4gl=.4go) FORM = $(FORM:.per=.frm) CCODE: $(OBJS) c4gl –o $(PROG_NAME) $(COBJS) @-echo “Finished Compiling ccode…”

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File Extensions Extension

Description

.4gl

Informix 4GL source module

.4ge

C Compiled version executable

.o

C Compiled version object

.4go

RDS Version object

.4gi

RDS Version executable

.per

Form File Source

.frm

Form File Compiled

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DEFINING VARIABLES SYNTAX: DEFINE variablename data-type Example: DEFINE fname CHAR(10) DEFINE start_date DATE DEFINE x,y,z INTEGER (OR) DEFINE fname CHAR(10), start_date DATE, x,y,z

INTEGER

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Initialization of Variables LET: Assigns value to a variable. Example: LET fname = “John” Let x = 5 Initialize: INITIALIZE variables to NULL Example: INITIALIZE lname TO NULL

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Scope of Variables »Global »Module »Local EXAMPLE:

glob.4gl GLOBALS DEFINE var1 CHAR(1) END GLOBALS

emp_main.4gl GLOBALS “Glob.4gl” DEFINE var2 SMALLINT MAIN DEFINE var3 INTEGER CALL funct1() END MAIN FUCTION funct1() DEFINE var4 CHAR(1) END FUNCTION

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Variable Scope var1

Global

var2

Module

Var3

Local

var4

Local

COMMENTS in 4GL »A pair of hyphens or minus signs -- this is a comment »The pound (or sharp) symbol # this is a comment »Left and right braces { this comment is multi-line} »Conditional comments --@ --# | © Kanbay Incorporated. All Rights Reserved

Decision and Looping Statements » IF » CASE » WHILE » FOR

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Decisions: IF Statement SYNTAX: IF ……THEN ………….. ELSE ……. END IF

Example : IF var_name MATCHES “[Yy]” THEN ERROR “Customer will be deleted.” ELSE ERROR “Delete cancelled.” END IF.

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IF Within Other Statements Syntax:

IF ….THEN IF…..THEN …………… END IF END IF

EXAMPLE: IF state=“IL” THEN IF zipcode MATCHES “601*” THEN ERROR “City is Schaumburg” END IF END IF

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Decisions: CASE statement Syntax: CASE WHEN {expr/Boolean-expr} statement….. [EXIT CASE] ……… [OTHERWISE] statement…. [EXIT CASE] END CASE

Example: CASE WHEN answervar=“Y” MESSAGE “Answered Yes.” WHEN answervar=“N” MESSAGE “Answered NO.” OTHERWISE MESSAGE “Bad Answer.” END CASE.

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Logical Loop: WHILE Loop Syntax: WHILE Boolean expression statement(s)…. [EXIT WHILE]…… [CONTINUE WHILE]….. END WHILE

EXAMPLE: WHILE boss_in_office = TRUE CALL act_busy() RETURNING boss_in_office END WHILE

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FOR Loop Syntax: FOR integer variable = integer expression to integer expression [STEP integer expression] statement…… [CONTINUE FOR]……. [EXIT FOR]………. END FOR

Example: DEFINE i SMALLINT FOR i=1 TO 10 DISPLAY “i = “, i AT i,1 END FOR

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SCREEN: »The screen is the area of the terminal where you can display the information. »Default size of the screen is 24*80 »Informix -4GL allows you to break the screen area into smaller sections called windows.

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WINDOW OPEN WINDOW windowname AT screenparameters WITH no of rows ,no of columns [ATTRIBUTE(attribute-list)] Example: OPEN WINDOW w_yesno AT 10,10 WITH 4 ROWS,20 COLUMNS ATTRIBUTE (BORDER)

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Screen Interaction Statements »ERROR »DISPLAY »MESSAGE »PROMPT

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MESSAGE: Syntax: MESSAGE display-list [ATTRIBUTE(attribute-list)] Example: MESSAGE “Press the first letter of an option.” ATTRIBUTE (REVERSE) ATTRIBUTES: UNDERLINE

REVERSE

INVISIBLE

BOLD

BLINK

NORMAL

DIM | © Kanbay Incorporated. All Rights Reserved

ERROR Syntax: ERROR display-list [ATTRIBUTE(attribute-list)] EXAMPLE: ERROR “No Rows Found.” ATTRIBUTES: UNDERLINE

REVERSE

INVISIBLE

BOLD

BLINK

NORMAL

DIM | © Kanbay Incorporated. All Rights Reserved

DISPLAY Syntax: DISPLAY “message” [AT row, column] [ATTRIBUTE (attribute-list)] EXAMPLE: DISPLAY “Row Added.” AT 22,3 ATTRIBUTE (reverse) ATTRIBUTES: UNDERLINE

REVERSE

INVISIBLE

BOLD

BLINK

NORMAL

DIM | © Kanbay Incorporated. All Rights Reserved

PROMPT SYNTAX: PROMPT “message” [ATTRIBUTE (attribute-list)] FOR [CHAR] variable [ATTRIBUTE (attribute-list)] END PROMPT EXAMPLE: PROMPT “Are You Sure? Y/N” FOR CHAR answer ATTRIBUTES: UNDERLINE

REVERSE INVISIBLE

BOLD

BLINK

DIM | © Kanbay Incorporated. All Rights Reserved

NORMAL

OPTIONS EXAMPLE: OPTIONS MESSAGE LINE FIRST + 2, ERROR LINE 23, PROMPT LINE LAST -3

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Syntax for creation and compiling of a Form »To create a default form use form4gl –d »To compile a form named filename.per use form4gl filename The .per extension is eliminated

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FORM »MANDATORY sections Database section Screen section Attribute section »OPTIONAL Sections Table section Instruction section

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Database Section The DATABASE section identifies the database (if any) on which the form is based. This can be any database that the engine can access, including remote databases. The DATABASE section is required , even if the form does not reference any database tables/columns. Syntax: » DATABASE FORMONLY You can specify only one database. Example : » DATABASE xyz » DATABASE xyz@server To create a form that is not related to any database , use FORMONLY and omit the TABLES section. Also , the table name has to be formonly in the ATTRIBUTES section for each of the field in the screen.

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ATTRIBUTE SECTION »It links display fields to database columns by using field tags

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FORM ATTRIBUTES: »AUTONEXT »COLOR »COMMENTS »UPSHIFT »DOWNSHIFT »DEFAULT »REQUIRED »INVISIBLE »REVERSE »WORDWRAP »NOENTRY »VERIFY »INCLUDE

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TABLE SECTION »The TABLES section lists the database tables that are referenced in the specification file. »You must list in this section any table, view or synonym whose column is referenced in the form. »The table CANNOT be a temporary table.

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Instruction Section »Used to define screen records and screen arrays »Change the default delimiters for display fields.

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OPEN FORM Syntax: OPEN FORM form-name FROM form-file Example: OPEN FORM cust FROM “cust_form” Cust_form :Name that you gave the form when it was created Cust

:How you will refer to the form throughout the program.

OPEN FORM only loads the form onto the memory and does not display it. | © Kanbay Incorporated. All Rights Reserved

FORM DISPLAY FORM: DISPLAY FORM cust Opens the form from the memory. CLEAR SCREEN: Clears the form from the screen but the form still exists in the memory. CLOSE FORM: CLOSE FORM cust Removes the form from the memory.

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