Select 来自 2 个表的单个值

Question

Im newbie at Sap/ABAP programming so i have question now I have 2 tables have same value, i need to do is check first table for a value if the table dont have the value check the second one and get the value there,

i have exprience in c and java a little but ABAP kind of different some how. And my code look like this.

IF NOT ATEXT is  initial. 
    SELECT SINGLE ATEXT FROM tablea WHERE aname EQ .....
    INTO DATA(a).
ELSE
   SELECT SINGLE BTEXT FROM  tableb  WHERE aname EQ .....
    INTO DATA(a).
ENDIF

1)can we do this with just joins or unıons?

2)or after first select single if there is no value return a if sy-subrc=4 and get another single select work out? i just think this solutions but cant figure out how...

Thanks for the answers. Best Regards.

Answer 1

You already know the correct way.

You need first to select from tablea . After, you check if sy-subrc = 4 (row not found) then it means that you need to select from tableb.

Basically your code would look like this:

SELECT SINGLE ATEXT FROM tablea WHERE aname EQ .....INTO DATA(a).
IF sy-subrc = 4. "Row not found
   SELECT SINGLE BTEXT FROM  tableb  WHERE aname EQ .....INTO DATA(a).
ELSE.
  "Value found in tablea
ENDIF.

Alternatively you can check if sy-subrc = 0 after first select (meaning row was found), else you select from tableb .

Ideally you also would check the sy-subrc after select on tableb (but this depends on the logic that consumes this data).

Overall, there are several ways to structure the code in this case (you can check for sy-subrc = 0, sy-subrc <> 0, sy-subrc = 4, check if the variable a is INITIAL or not after the select), so you will need to choose one.

Also don't forget to test sy-subrc directly after the SELECT (don't execute any other code in between since other statements can also set the value of the sy-subrc).

Answer 2

You almost got it.

1. Select the 1st table whether it got the value specified

SELECT SINGLE ATEXT FROM tablea WHERE aname EQ..... INTO DATA(a).

2. The next approach can be either check if the select successfully return row of data (by subrc) or just simply check the internal table tablea itself if it contains value after the SELECT query.

Either with IF sy-subrc NE 0 or IF tablea IS INITIAL

The second command INITIAL means the internal table empty

3. Select the second table

SELECT SINGLE BTEXT FROM tableb WHERE aname EQ..... INTO DATA(a).

So overall the code looks something like this

SELECT SINGLE ATEXT FROM tablea WHERE aname EQ .....
INTO DATA(a).

IF tablea IS INITIAL. "if tablea is empty
    SELECT SINGLE BTEXT FROM  tableb  WHERE aname EQ .....
    INTO DATA(a).
ENDIF.

or

SELECT SINGLE ATEXT FROM tablea WHERE aname EQ .....
INTO DATA(a).

IF sy-subrc NE 0. "Apart from 0 means previous command not executed properly
    SELECT SINGLE BTEXT FROM  tableb  WHERE aname EQ .....
    INTO DATA(a).
ENDIF.