In ABAP, How to select all the data into my internal table using loops?

In ABAP, there are different ways to select data into internal tables using loops and joins. Understanding the performance implications of different approaches is crucial for efficient programming.

Using JOIN Statements with Internal Tables

One approach is to join all tables in a single SELECT statement. Here's an example ?

SELECT t11~orgeh t11~msty t11~mshort t12~position t13~job t14~job_grade t14~scheme
  INTO gt_my_combined_table
  FROM zgerpt_rnk_min as t11
  JOIN hrp1001 as t12
    ON t11~orgeh = t12~objid
  JOIN hrp1001 as t13
    ON t12~position = t13~objid
  JOIN hrp9003 as t14
    ON t13~job = t14~objid
WHERE t12~otype = 'O' AND
      t12~sclas = 'S' AND
      t12~begda LE p_keydt AND
      t12~endda GE p_keydt AND
      t12~plvar = '01' AND
      t12~istat = '1' AND
      t12~objid IN (pnpobjid) AND
      t13~otype = 'S' AND
      t13~sclas = 'C' AND
      t13~begda LE p_keydt AND
      t13~endda GE p_keydt AND
      t14~begda LE p_keydt AND
      t14~endda GE p_keydt.

Performance Consideration: The main problem with this complex JOIN statement is that it can be difficult to determine which key or index the database will use, potentially making it inefficient for large datasets.

Performance Analysis Tools

Using Transaction SAT

To check the runtime performance of your program, you can use T-Code: SAT (ABAP Runtime Analysis Tool). This transaction determines the most efficient statements in your program and provides ideas for performance improvement.

Using Transaction ST05

You can also use T-Code ST05 (Performance Trace) to measure the performance of your program. This transaction is used to run performance traces in the SAP system, allowing you to analyze SQL statements and their execution times.

Best Practices

When selecting data into internal tables using loops:

• Use appropriate WHERE clauses to limit data selection
• Consider using FOR ALL ENTRIES for better performance with large datasets
• Analyze your queries using SAT and ST05 to identify bottlenecks
• Ensure proper indexing on database tables

Conclusion

Selecting data into internal tables efficiently requires careful consideration of JOIN strategies and regular performance analysis using tools like SAT and ST05 to optimize your ABAP programs.