Set path vs current schema

Set Current Schema

• ‘The CURRENT SCHEMA special register specifies a VARCHAR(128) value that identifies the schema name used to qualify unqualified database object references where applicable in dynamically prepared SQL statements. ‘– Copied IBM’s SQL reference manual

We set the current schema. We created a User Defined field and

then tried to use it in a create table statement. The create table

failed because the statement couldn’t find the user defined

type.

Why?

Current Path

• ‘The CURRENT PATH special register specifies the SQL path used to resolve unqualified distinct type names, function names, and procedure names in dynamically prepared SQL statements.’ – Copied from IBM’s SQL Reference Manual

• Set path = ‘collection’

Function Foot Prints!

Watch your parameter definitions!

CL Programming Review

CL Restrictions

• Only open 5 files

• Cannot update files

• Only 25 levels of nested iteration and selection statements

• Cannot create reports – only execute them

Begin and end

• PGM– Also used to include parameters passed to

the program

• ENDPGM– Last statement executed and control returns

to the calling program

Declaring Variables

• Declaring files (DCLF)– Specify the file name– If more than one file used in the program than

specify the opnid– Limit of 5 files open in the program

• Declaring variables (DCL)– *DEC, *CHAR, *LGL, *INT, *UINT– Date, Time, and Timestamp variables are

treated as *CHAR

Defining a Logical Block

Do

Enddo

• Can be embedded in iteration, and selection statements

Iteration

Dowhile (condition)

Enddo

• Tests the condition first. If the condition is true, then the logic block is executed.

Iteration

Dountil (condition)

Enddo

• Tests the condition after the logic block is executed

• In other words, the logic block is always executed at least once.

Iteration

DOFOR &variable &from &to &by

ENDO

• Executes the loop by checking the contents of &variable. &variable starts the the &from value. The loop ends when &variable reaches the &to value. &variable is incremented by the &by variable. If &by is left out then &variable is incremented by 1.

Selection

If (condition)

Else

End-if.

• Allows execution of code based on a condition. If the condition is false, then the else logic is executed.

• If statements process only one CL command if true and one CL command if false

• Often used in combination with the DO ENDDO logic block.

Selection

SelectWhen cond(condition 1) then(cl command)

When cond(condition 2) then(cl command)Otherwise (cl command)

Endselect

• Executes the first true condition and then exits the structure

Working with Files

• RCVF OPNID(openidname)– Reads records from a file– Works with database files and display files

• SNDF OPNID(openidname)– Writes to a file– Works only with display files

• SNDRCVF OPNID(openidname)– Reads a record from a file– Writes to a file– Works only with display files

• OPNID only needed if more than one file is opened in the program

MONitoring for MeSsaGes

• MONMSG MSGID(CPF9999) EXEC(cl command)

• Used to trap error messages

• Used to avoid the Black Screen of Death

Indicators

• Used in display file to pass information between the program and the display file.

• Two types of indicators– Response (ie function keys)– Option (ie reverse image)

Happy Birthday Program

Write an interactive program that prompts for a userid and sends a happy birthday greeting to that user. Program should terminate when

F3 is pressed

CL commands for the lab

• RUNSQLSTM

• DSPOBJD

• DSPFD

• DSPDBR

• DSPOBJAUT

• RTVJOBA

• DSPSPLF