Www.PrismaTech.net Jump-Start Embedded SQL into RPG Presented by: Robert Arce.

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Jump-Start Embedded SQL Jump-Start Embedded SQL into RPGinto RPG

Presented by:

Robert Arce

Jump-Start embedded SQL into RPG by Robert Arce

Why SQL in RPG?Why SQL in RPG?

Useful for ad hoc retrieval and update

Easy manipulation of data

SQL alone may not provide logic capabilities to perform required operations

SQL has no user interface

ad hoc statements can be complex

sorting possibilities are enhanced by SQL


SQL embedded typesSQL embedded types

Static statements – structure of the statement does NOT change

Static “select into” statementsDynamic StatementsCursors – to handle multiple retrieves


SQL source typeSQL source type

SQLRPGDB2/400 Query Manager RPG

SQLRPGLE DB2 Query Manager RPG/400 Integrated

Language Environment


Create SQL ILE RPG ObjectCreate SQL ILE RPG Object

CRTSQLRPGIPrecompiles SQL statements creates

RPGLE source file in QTEMP/QSQLTEMP1 (ToSrcFile option)

Create Bound RPG program CRTBNDRPGVoila! you have a program


Precompiler DirectivesPrecompiler Directives

Only one SQL statement

C/exec sql --open sql code

C+ update CUSMS

C+ set CMREPS=233

C+ where CMREPS=5

C/end-exec -- close sql code


Host VariablesHost VariablesRPG program variables are use within the SQL statements

C/exec sql --open sql code

C+ update CUSMS

C+ set CMREPS=:newslsrep

C+ where CMREPS=:oldslsrep

C/end-exec -- close sql code


Indicator Variable ~ NullIndicator Variable ~ Null

Indicator variable can optionally be coded after the host variable

Two ways to declare Indicator variable:Dindnul_1 s 5i 0

Dindnul_2 s 4b 0

Assign negative (-1) as null or positive (0) as not null


Indicator VariableIndicator Variable

C+ set SHIPTO=:newshipto:indshipSame as:

if indship = -1

SHIPTO = null

else

SHIPTO = newshipto

endif


Select IntoSelect IntoONLY retrieve ONE row or NADA! Into clause must list one host variable for

each column in the select listOptionally and is suggested to use an

indicator variable per each rowCan select all fields “*” and assign them

into the proper Data structuresqlstt = '21000‘ more than one row


Select IntoSelect Into * Set host variables

C customer=700583 *C/exec sqlC+ select CMCSNO, --customer numberC+ CMCSNM, --customer nameC+ CMDFSH --default shipto C+ into :csCMCSNO, C+ :csCMCSNM, C+ :csCMDFSH :inCMDFSHC+ from CUSMSC+ where CMCSNO=:customerC/end-exec


Dynamic SQLDynamic SQL

Construct in string variables on the flyExecute immediate vs Prepare and executePrepare takes extra time building statement

but execution runs fasterParameter markers ‘?’ define in the

Using clause with one host variable per marker


Dynamic Dynamic execute immediateexecute immediate

* Assign SQL statement dynsqlstm='delete from CUSMS where '+ 'CMCSNM LIKE '+'''%CAR%''‘

* default when create pgm COMMIT =*CHG

C/exec sql set option commit=*none C/end-exec C/exec sql C+ execute immediate :dynsqlstm C/end-exec


Dynamic Dynamic Prepare-executePrepare-execute

Prepare Statement-Name from :host-variable

C/exec sql --Part 1

C+ prepare dltcuscar C+ from :dynsqlstm C/end-exec * C if sqlstt = '00000'C/exec sql -- Part 2

C+ execute dltcuscar C/end-exec


Dynamic Dynamic Prepare-Parameter MarkerPrepare-Parameter Marker

dynsqlstm='delete from CUSMS where CMCSNM like ?' C/exec sql C+ prepare dltcustcar C+ from :dynsqlstm C/end-exec C if sqlstt = '00000'C eval namelike ='%CAR%‘ *C/exec sql C+ execute dltcustcar C+ using :namelike C/end-exec


CursorsCursorsCursors open more than one rowIs based on Select statementsAllow you to do data manipulation

• Sorts• Sums• Use Host Variable for sorts and selections

Declare as read-only or updatable


CursorsCursorsDeclare cursorOpen the cursorFetch – like read records (rows) from cursor

(optionally update or delete the most recently fetched record)

Close cursor (cursor must be open)


Cursor - DeclareCursor - DeclareC/exec sql

C+ declare custcursor cursor

C+ for select CMCSNO, CMCSNM, CMDFSH

C+ from CUSMS

C+ where CMCSNM like :namelike

C+ order by :custsort

C+ for read only

C/end-exec


Cursor - OpenCursor - OpenHost variables are evaluated only when the cursor is

open

* sets values for the host variablesC eval namelike = '%CAR%' C eval custsort = 'CMCSNO'C/exec sqlC+ open custcursorC/end-exec


Cursor - FetchCursor - FetchC dow morerowsC/exec sql C+ Fetch Next C+ from custcursor C+ into :csCMCSNO, C+ :csCMCSNM, C+ :csCMDFSH C/end-exec


Cursors - UpdateCursors - Update

In the declare cursor statement replace:

“for read only” by “for update of CMREPS” After the fetch do the update:

C/exec sql

C+ update CUSMS

C+ set CMREPS=:newslsrep

C+ where current of custcursor --name of the cursor

C/end-exec


Cursor - DynamicCursor - DynamicC/exec sql

C+ declare custcursor cursor

C+ for selcustcar

C/end-exec

* Asssign sql to host variable:

sqlstm='select CMCSNO,CMCSNM,CMDFSH '+

'from CUSMS ' +

'where CMCSNM like ? ' +

'order by CMCSNO'


Cursor - DynamicCursor - DynamicC/exec sql C+ prepare selcustcar C+ from :dynsqlstm C/end-exec C if sqlstt ='00000' * sets parameter marker valueC eval namelike='%CAR%'C/exec sqlC+ open custcursorC+ using :namelikeC/end-exec


Fetch PositionFetch Position

Next - Prior First - Last Before before the first row After after the last row Current no change in position Relative n

negative ~ previous positive ~ next


referencesreferences

DB2 UDB for iSeries SQL programming

http://publib.boulder.ibm.com/iseries/v5r1/ic2924/index.htm?info/sqlp/rbafymst02.htm

SQL/400 developer’s guide by Paul Conte and Mike Cravitz

Www.PrismaTech.net Jump-Start Embedded SQL into RPG Presented by: Robert Arce.

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