topic Re: Enque and Deque in Application Development and Automation Discussions

Enque and Deque

Former Member — Mon, 26 May 2008 12:49:54 GMT

Hi all,

Can any one explain with example how to use Enque and Deque to lock a database table?

Re: Enque and Deque

Former Member — Mon, 26 May 2008 13:21:23 GMT

I think if you search the ABAP Forum you will get the answer.

Thanks

Arghadip

Re: Enque and Deque

Former Member — Wed, 28 May 2008 04:35:05 GMT

hi,

Activating a lock object in the ABAP Dictionary automatically creates function modules for setting (ENQUEUE_<lock object name>) and releasing (DEQUEUE_<lock object name>) locks.

check the link :

http://help.sap.com/saphelp_nw70/helpdata/en/41/7af4c8a79e11d1950f0000e82de14a/content.htm

Re: Enque and Deque

prasanth_kasturi — Wed, 28 May 2008 04:39:18 GMT

hi,

check the below examle

check tcode abapdocu--~~>abapdatabaseacees~~--->setting and releasing locks

REPORT demo_transaction_enqueue MESSAGE-ID sabapdocu.

TABLES sflight.

DATA text(8) TYPE c.

DATA ok_code TYPE sy-ucomm.

CALL SCREEN 100.

MODULE init OUTPUT.

SET PF-STATUS 'BASIC'.

sflight-carrid = 'LH'. sflight-connid = '400'.

ENDMODULE.

MODULE exit INPUT.

LEAVE PROGRAM.

ENDMODULE.

MODULE enqueue INPUT.

CASE ok_code.

WHEN 'ENQUEUE'.

CALL FUNCTION 'ENQUEUE_EDEMOFLHT'

EXPORTING

mode_sflight = 'X'

carrid = sflight-carrid

connid = sflight-connid

fldate = sflight-fldate

EXCEPTIONS

foreign_lock = 1

system_failure = 2

OTHERS = 3.

CASE sy-subrc.

WHEN 0.

MESSAGE i888 WITH 'Enqueue successful'(001).

WHEN 1.

text = sy-msgv1.

MESSAGE e888 WITH 'Record already'(002) 'locked by'(003)

text.

CALL TRANSACTION 'SM12'.

WHEN 2 OR 3.

MESSAGE e888 WITH 'Error in enqueue!'(004)

'SY-SUBRC:' sy-subrc.

ENDCASE.

WHEN 'DEQUEUE'.

CALL FUNCTION 'DEQUEUE_EDEMOFLHT'

EXPORTING

mode_sflight = 'X'

carrid = sflight-carrid

connid = sflight-connid

fldate = sflight-fldate

EXCEPTIONS

OTHERS = 1.

CASE sy-subrc.

WHEN 0.

MESSAGE i888 WITH 'Dequeue successful'(005).

WHEN 1.

MESSAGE e888 WITH 'Error in dequeue!'(006).

ENDCASE.

WHEN 'SM12'.

CALL TRANSACTION 'SM12'.

ENDCASE.

ENDMODULE.

MODULE select INPUT.

CASE ok_code.

WHEN 'SELECT'.

SELECT * FROM sflight WHERE carrid = sflight-carrid

AND connid = sflight-connid

AND fldate = sflight-fldate.

ENDSELECT.

MESSAGE i888 WITH 'SY-SUBRC:' sy-subrc.

ENDCASE.

ENDMODULE.

reward if helpful

prasanth

Re: Enque and Deque

Former Member — Wed, 28 May 2008 04:55:36 GMT

Hi,

Check out this link. It would be helpful.

http://help.sap.com/saphelp_nw70/helpdata/en/41/7af4c5a79e11d1950f0000e82de14a/content.htm

Thanks

Reward points if useful

Re: Enque and Deque

Former Member — Wed, 28 May 2008 04:58:38 GMT

Hi,

To add on about the function modules-

Two function modules, one for setting locks and the other for releasing them, are automatically generated upon successful activation of the lock object in the ABAP Dictionary. They are of the form ENQUEUE_* and DEQUEUE_*. If we created the lock object E_MYLOCKOBJ, the corresponding locking and unlocking function modules generated would be ENQUEUE_ E_MYLOCKOBJ and DEQUEUE_E_MYLOCKOBJ, respectively.

http://articles.techrepublic.com.com/5100-10878_11-5066352.html

Thanks

Reward points if useful

Re: Enque and Deque

Former Member — Wed, 28 May 2008 04:59:23 GMT

Hi Rajashri,

Locking is quite simple..

lock the table using Function Module

ENQUEUE_TABLE_E (pass Table Name.)

....Write your update statements....

Now unlock the Table using Function Module

DEQUEUE_TABLE_E.

Please reward if useful

Manish Sharma

Re: Enque and Deque

Former Member — Fri, 30 May 2008 11:03:30 GMT

hi,

i am providing code to you.

&----

*& Report ZLOCKING *

*& *

&----

*& *

&----

REPORT zlocking .

DATA : tab_emp TYPE TABLE OF zemp_51772,

wa_emp TYPE zemp_51772.

wa_emp-emp_no = '102'.

wa_emp-emp_id = '157'.

wa_emp-emp_name = 'SIVA'.

wa_emp-emp_dept = 'SAP'.

APPEND wa_emp TO tab_emp.

CLEAR wa_emp.

wa_emp-emp_no = '128'.

wa_emp-emp_id = '138'.

wa_emp-emp_name = 'RAMA'.

wa_emp-emp_dept = 'SAP'.

APPEND wa_emp TO tab_emp.

CLEAR wa_emp.

wa_emp-emp_no = '133'.

wa_emp-emp_id = '121'.

wa_emp-emp_name = 'KRISHNA'.

wa_emp-emp_dept = 'SAP'.

APPEND wa_emp TO tab_emp.

CLEAR wa_emp.

CALL FUNCTION 'ENQUEUE_E_TABLEE'

EXPORTING

mode_rstable = 'X'

tabname = 'ZEMP_51772'

varkey =

X_TABNAME = ' '

X_VARKEY = ' '

_SCOPE = '2'

_WAIT = ' '

_COLLECT = ' '

EXCEPTIONS

foreign_lock = 1

system_failure = 2

OTHERS = 3

IF sy-subrc EQ 0.

INSERT zemp_51772 FROM TABLE tab_emp.

ENDIF.

CALL FUNCTION 'DEQUEUE_E_TABLEE'

EXPORTING

mode_rstable = 'X'

tabname = 'ZEMP_51772'

VARKEY =

X_TABNAME = ' '

X_VARKEY = ' '

_SCOPE = '3'

_SYNCHRON = ' '

_COLLECT = ' '

IF sy-subrc EQ 0.

WRITE:/ 'Unlocked the Table'.

ENDIF.

now you will get it how to use enque and dequeue

regards,

vipul

Re: Enque and Deque

Former Member — Fri, 30 May 2008 11:07:54 GMT

this editable alv using this to make change in standard table.

&----

*& Report ZALVF

&----

REPORT ZALVF.

*******************************************************************

TYPE-POOLS *

*******************************************************************

TYPE-POOLS: SLIS.

*******************************************************************

INTERNAL TABLES/WORK AREAS/VARIABLES *

*******************************************************************

DATA: I_FIELDCAT TYPE SLIS_T_FIELDCAT_ALV,

I_INDEX TYPE STANDARD TABLE OF I WITH HEADER LINE,

W_FIELD TYPE SLIS_FIELDCAT_ALV,

P_TABLE LIKE DD02L-TABNAME,

DY_TABLE TYPE REF TO DATA,

DY_TAB TYPE REF TO DATA,

DY_LINE TYPE REF TO DATA.

*******************************************************************

FIELD-SYMBOLS *

*******************************************************************

FIELD-SYMBOLS: <DYN_TABLE> TYPE STANDARD TABLE,

<DYN_WA> TYPE ANY,

<DYN_FIELD> TYPE ANY,

<DYN_TAB_TEMP> TYPE STANDARD TABLE.

*******************************************************************

SELECTION SCREEN *

*******************************************************************

PARAMETERS: TABNAME(30) TYPE C,

LINES(100) TYPE N.

*******************************************************************

START-OF-SELECTION *

*******************************************************************

START-OF-SELECTION.

Storing table name

P_TABLE = TABNAME.

Create internal table dynamically with the stucture of table name
entered in the selection screen

CREATE DATA DY_TABLE TYPE STANDARD TABLE OF (P_TABLE).

ASSIGN DY_TABLE->* TO <DYN_TABLE>.

IF SY-SUBRC <> 0.

MESSAGE I000(Z_ZZZ_CA_MESSAGES) WITH ' No table found'.

LEAVE TO LIST-PROCESSING.

ENDIF.

Create workarea for the table

CREATE DATA DY_LINE LIKE LINE OF <DYN_TABLE>.

ASSIGN DY_LINE->* TO <DYN_WA>.

Create another temp. table

CREATE DATA DY_TAB TYPE STANDARD TABLE OF (P_TABLE).

ASSIGN DY_TAB->* TO <DYN_TAB_TEMP>.

SORT I_FIELDCAT BY COL_POS.

Select data from table

SELECT * FROM (P_TABLE)

INTO TABLE <DYN_TABLE>

UP TO LINES ROWS.

REFRESH <DYN_TAB_TEMP>.

Display report

CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'

EXPORTING

I_CALLBACK_PROGRAM = SY-REPID

I_STRUCTURE_NAME = P_TABLE

I_CALLBACK_USER_COMMAND = 'USER_COMMAND'

I_CALLBACK_PF_STATUS_SET = 'SET_PF_STATUS'

TABLES

T_OUTTAB = <DYN_TABLE>

EXCEPTIONS

PROGRAM_ERROR = 1

OTHERS = 2.

IF SY-SUBRC <> 0.

ENDIF.

&----

*& Form SET_PF_STATUS

&----

Setting custom PF-Status

----

-->RT_EXTAB Excluding table

----

FORM SET_PF_STATUS USING RT_EXTAB TYPE SLIS_T_EXTAB.

SET PF-STATUS 'Z_STANDARD'.

ENDFORM. "SET_PF_STATUS

&----

*& Form user_command

&----

Handling custom function codes

----

-->R_UCOMM Function code value
-->RS_SELFIELD Info. of cursor position in ALV

----

FORM USER_COMMAND USING R_UCOMM LIKE SY-UCOMM

RS_SELFIELD TYPE SLIS_SELFIELD.

Local data declaration

DATA: LI_TAB TYPE REF TO DATA,

L_LINE TYPE REF TO DATA.

Local field-symbols

FIELD-SYMBOLS:<L_TAB> TYPE TABLE,

<L_WA> TYPE ANY.

Create table

CREATE DATA LI_TAB TYPE STANDARD TABLE OF (P_TABLE).

ASSIGN LI_TAB->* TO <L_TAB>.

Create workarea

CREATE DATA L_LINE LIKE LINE OF <L_TAB>.

ASSIGN L_LINE->* TO <L_WA>.

CASE R_UCOMM.

When a record is selected

WHEN '&IC1'.

Read the selected record

READ TABLE <DYN_TABLE> ASSIGNING <DYN_WA> INDEX

RS_SELFIELD-TABINDEX.

IF SY-SUBRC = 0.

Store the record in an internal table

APPEND <DYN_WA> TO <L_TAB>.

Fetch the field catalog info

CALL FUNCTION 'REUSE_ALV_FIELDCATALOG_MERGE'

EXPORTING

I_PROGRAM_NAME = 'Z_DEMO_PDF_JG'

I_STRUCTURE_NAME = P_TABLE

CHANGING

CT_FIELDCAT = I_FIELDCAT

EXCEPTIONS

INCONSISTENT_INTERFACE = 1

PROGRAM_ERROR = 2

OTHERS = 3.

IF SY-SUBRC = 0.

Make all the fields input enabled except key fields

W_FIELD-INPUT = 'X'.

MODIFY I_FIELDCAT FROM W_FIELD TRANSPORTING INPUT

WHERE KEY IS INITIAL.

ENDIF.

Display the record for editing purpose

CALL FUNCTION 'REUSE_ALV_LIST_DISPLAY'

EXPORTING

I_CALLBACK_PROGRAM = SY-REPID

I_STRUCTURE_NAME = P_TABLE

IT_FIELDCAT = I_FIELDCAT

I_SCREEN_START_COLUMN = 10

I_SCREEN_START_LINE = 15

I_SCREEN_END_COLUMN = 200

I_SCREEN_END_LINE = 20

TABLES

T_OUTTAB = <L_TAB>

EXCEPTIONS

PROGRAM_ERROR = 1

OTHERS = 2.

IF SY-SUBRC = 0.

Read the modified data

READ TABLE <L_TAB> INDEX 1 INTO <L_WA>.

If the record is changed then track its index no.
and populate it in an internal table for future
action

IF SY-SUBRC = 0 AND <DYN_WA> <> <L_WA>.

<DYN_WA> = <L_WA>.

I_INDEX = RS_SELFIELD-TABINDEX.

APPEND I_INDEX.

ENDIF.

When save button is pressed

WHEN 'SAVE'.

Sort the index table

SORT I_INDEX.

Delete all duplicate records

DELETE ADJACENT DUPLICATES FROM I_INDEX.

LOOP AT I_INDEX.

Find out the changes in the internal table
and populate these changes in another internal table

READ TABLE <DYN_TABLE> ASSIGNING <DYN_WA> INDEX I_INDEX.

IF SY-SUBRC = 0.

APPEND <DYN_WA> TO <DYN_TAB_TEMP>.

ENDIF.

ENDLOOP.

Lock the table

CALL FUNCTION 'ENQUEUE_E_TABLE'

EXPORTING

MODE_RSTABLE = 'E'

TABNAME = P_TABLE

EXCEPTIONS

FOREIGN_LOCK = 1

SYSTEM_FAILURE = 2

OTHERS = 3.

IF SY-SUBRC = 0.

Modify the database table with these changes

MODIFY (P_TABLE) FROM TABLE <DYN_TAB_TEMP>.

REFRESH <DYN_TAB_TEMP>.

Unlock the table

CALL FUNCTION 'DEQUEUE_E_TABLE'

EXPORTING

MODE_RSTABLE = 'E'

TABNAME = P_TABLE.

ENDIF.

RS_SELFIELD-REFRESH = 'X'.

WHEN 'EXIT'.

LEAVE PROGRAM.

ENDCASE.

ENDFORM. "user_command