Performance tuning in selection criteria(bold)

Use the selection criteria

SELECT * FROM SBOOK.                    
  CHECK: SBOOK-CARRID = 'LH' AND        
                  SBOOK-CONNID = '0400'.         
ENDSELECT.                              

SELECT * FROM SBOOK                      
  WHERE CARRID = 'LH' AND                
        CONNID = '0400'.                 
ENDSELECT.                               

Use the aggregated functions

C4A = '000'.               
SELECT * FROM T100         
  WHERE SPRSL = 'D' AND    
        ARBGB = '00'.      
  CHECK: T100-MSGNR > C4A. 
  C4A = T100-MSGNR.        
ENDSELECT.                 

SELECT MAX( MSGNR ) FROM T100 INTO C4A  
 WHERE SPRSL = 'D' AND                 
       ARBGB = '00'.                   

Select with view

SELECT * FROM DD01L                     
  WHERE DOMNAME LIKE 'CHAR%'            
        AND AS4LOCAL = 'A'.             
  SELECT SINGLE * FROM DD01T            
    WHERE   DOMNAME    = DD01L-DOMNAME  
        AND AS4LOCAL   = 'A'            
        AND AS4VERS    = DD01L-AS4VERS  
        AND DDLANGUAGE = SY-LANGU.      
ENDSELECT.                              

SELECT * FROM DD01V                     
 WHERE DOMNAME LIKE 'CHAR%'            
       AND DDLANGUAGE = SY-LANGU.      
ENDSELECT.                              

Select with index support

SELECT * FROM T100             
 WHERE     ARBGB = '00'       
       AND MSGNR = '999'.     
ENDSELECT.                     

SELECT * FROM T002.              
  SELECT * FROM T100             
    WHERE     SPRSL = T002-SPRAS 
          AND ARBGB = '00'       
          AND MSGNR = '999'.     
  ENDSELECT.                     
ENDSELECT.                       

Select … Into table

REFRESH X006.                  
SELECT * FROM T006 INTO X006.  
  APPEND X006.                 
ENDSELECT

SELECT * FROM T006 INTO TABLE X006.

Select with selection list

SELECT * FROM DD01L               
  WHERE DOMNAME LIKE 'CHAR%'      
        AND AS4LOCAL = 'A'.       
ENDSELECT

SELECT DOMNAME FROM DD01L     
 INTO DD01L-DOMNAME          
 WHERE DOMNAME LIKE 'CHAR%'  
       AND AS4LOCAL = 'A'.   
ENDSELECT

Key access to multiple lines

LOOP AT TAB.           
 CHECK TAB-K = KVAL.  
 " ...                
ENDLOOP.               

LOOP AT TAB WHERE K = KVAL.      
  " ...                          
ENDLOOP.                         

Copying internal tables

REFRESH TAB_DEST.               
LOOP AT TAB_SRC INTO TAB_DEST.  
  APPEND TAB_DEST.              
ENDLOOP.                        

TAB_DEST[] = TAB_SRC[].

Modifying a set of lines

LOOP AT TAB.              
  IF TAB-FLAG IS INITIAL. 
    TAB-FLAG = 'X'.       
  ENDIF.                  
  MODIFY TAB.             
ENDLOOP.                  

TAB-FLAG = 'X'.                   
MODIFY TAB TRANSPORTING FLAG      
           WHERE FLAG IS INITIAL. 

Deleting a sequence of lines

DO 101 TIMES.                
  DELETE TAB_DEST INDEX 450. 
ENDDO.                       

DELETE TAB_DEST FROM 450 TO 550.

Linear search vs. binary

READ TABLE TAB WITH KEY K = 'X'.

READ TABLE TAB WITH KEY K = 'X' BINARY SEARCH.

Comparison of internal tables

DESCRIBE TABLE: TAB1 LINES L1,       
                TAB2 LINES L2.       
                                     
IF L1 <> L2.                         
  TAB_DIFFERENT = 'X'.               
ELSE.                                
  TAB_DIFFERENT = SPACE.             
  LOOP AT TAB1.                      
    READ TABLE TAB2 INDEX SY-TABIX.  
    IF TAB1 <> TAB2.                 
      TAB_DIFFERENT = 'X'. EXIT.     
    ENDIF.                           
  ENDLOOP.                           
ENDIF.                               
                                     
IF TAB_DIFFERENT = SPACE.            
  " ...                              
ENDIF.                               

IF TAB1[] = TAB2[].   
 " ...               
ENDIF.                

Modify selected components

LOOP AT TAB.            
 TAB-DATE = SY-DATUM.  
 MODIFY TAB.           
ENDLOOP.                

WA-DATE = SY-DATUM.                     
LOOP AT TAB.                            
 MODIFY TAB FROM WA TRANSPORTING DATE. 
ENDLOOP.                                

Appending two internal tables

LOOP AT TAB_SRC.               
  APPEND TAB_SRC TO TAB_DEST.  
ENDLOOP

APPEND LINES OF TAB_SRC TO TAB_DEST.

Deleting a set of lines

LOOP AT TAB_DEST WHERE K = KVAL.  
  DELETE TAB_DEST.                
ENDLOOP

DELETE TAB_DEST WHERE K = KVAL.