From 6818f152ffde5253ab795411440f26986100409c Mon Sep 17 00:00:00 2001 From: danrega <16720986+danrega@users.noreply.github.com> Date: Mon, 18 Nov 2024 18:10:12 +0100 Subject: [PATCH] Update --- 01_Internal_Tables.md | 394 ++++++++++++++++++++++++++++++++++++++ 06_Dynamic_Programming.md | 11 ++ README.md | 4 +- 3 files changed, 408 insertions(+), 1 deletion(-) diff --git a/01_Internal_Tables.md b/01_Internal_Tables.md index 1135931..d7f4286 100644 --- a/01_Internal_Tables.md +++ b/01_Internal_Tables.md @@ -29,6 +29,7 @@ - [Examples of Addressing Individual Components of Read Lines](#examples-of-addressing-individual-components-of-read-lines) - [Excursions with READ TABLE Statements](#excursions-with-read-table-statements) - [System Field Setting in READ TABLE Statements](#system-field-setting-in-read-table-statements) + - [Specifying a WHERE Condition in READ TABLE Statements](#specifying-a-where-condition-in-read-table-statements) - [COMPARING and TRANSPORTING Additions: Comparing Fields and Specifying Fields for Transport](#comparing-and-transporting-additions-comparing-fields-and-specifying-fields-for-transport) - [CASTING and ELSE UNASSIGN Additions when Specifying Field Symbols as Target Areas](#casting-and-else-unassign-additions-when-specifying-field-symbols-as-target-areas) - [BINARY SEARCH Addition: Optimized Read Access When Specifying Free Keys](#binary-search-addition-optimized-read-access-when-specifying-free-keys) @@ -44,6 +45,7 @@ - [Defining the Step Size and the Direction of Loop Passes](#defining-the-step-size-and-the-direction-of-loop-passes) - [Iteration Expressions](#iteration-expressions) - [Interrupting and Exiting Loops](#interrupting-and-exiting-loops) + - [Inserting and Deleting Lines in Internal Tables in Loops](#inserting-and-deleting-lines-in-internal-tables-in-loops) - [Operations with Internal Tables Using ABAP SQL SELECT Statements](#operations-with-internal-tables-using-abap-sql-select-statements) - [Internal Tables as Target Data Objects in SELECT Queries](#internal-tables-as-target-data-objects-in-select-queries) - [SELECT Queries with Internal Tables as Data Sources](#select-queries-with-internal-tables-as-data-sources) @@ -1891,6 +1893,148 @@ ASSERT sy-tabix = 0.

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+#### Specifying a WHERE Condition in READ TABLE Statements + +- The syntax `READ TABLE ... WHERE ...` searches for the first line that matches a `WHERE` condition. +- The value of `sy-tabix` is set when a line is found, while `sy-subrc` are set to either 0 or 4. +- The `WHERE` condition can use comparison and predicate expressions (see the code snippet comments below for examples). +- Syntax options: + - The read result must be specified before the `WHERE` condition. + - The `TRANSPORTING NO FIELDS` and `USING KEY` additions are possible. + - Dynamic `WHERE` conditions are possible. +- If a `READ TABLE` statement can be expressed using `WITH KEY`, this approach - instead of using a `WHERE` condition - is recommended as it is more performant. A syntax warning occurs but can be suppressed with the pragma `##read_where_ok`. +- For optimized searches with a `WHERE` condition: + - No optimized search in standard tables without a secondary table key. + - For sorted and hashed keys (sorted/hashed tables, secondary table keys), the search is optimized as described [here](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenitab_where_optimization.htm), if specifications are transferable to a key access. + +```abap +"Creating and populating demo internal tables +TYPES: BEGIN OF s_demo, + comp1 TYPE i, + comp2 TYPE c LENGTH 5, + comp3 TYPE i, + comp4 TYPE c LENGTH 5, + END OF s_demo, + t_type_so TYPE SORTED TABLE OF s_demo WITH UNIQUE KEY comp1 WITH NON-UNIQUE SORTED KEY sk COMPONENTS comp3. + +DATA(itab) = VALUE t_type_so( ( comp1 = 1 comp2 = 'lorem' comp3 = 30 comp4 = 'ipsum' ) + ( comp1 = 2 comp2 = 'dolor' comp3 = 20 comp4 = 'sit' ) + ( comp1 = 3 comp2 = 'amet' comp3 = 40 comp4 = 'hello' ) + ( comp1 = 4 comp2 = 'world' comp3 = 50 comp4 = 'ABAP' ) + ( comp1 = 5 comp2 = 'test' comp3 = 10 comp4 = '' ) ). + +DATA wa TYPE s_demo. + +"--------- WHERE condition with comparison expressions --------- + +"Examples: =/EQ, <>/NE, >/GT, =,GE, <=/LE, +" CO, CN, CA, NA, CS, NS, CP, NP, +" [NOT] BETWEEN ... AND +" [NOT] IN ranges_tables + +READ TABLE itab INTO wa WHERE comp1 > 3. +ASSERT sy-tabix = 4. + +"'or' also available in other lines in this component, but the first found line +"is returned (lines 1, 2, 4) +READ TABLE itab INTO wa WHERE comp2 CS 'or'. +ASSERT sy-tabix = 1. + +"'d' occurs in lines 2, 4 +READ TABLE itab INTO wa WHERE comp2 CS 'd'. +ASSERT sy-tabix = 2. + +READ TABLE itab INTO wa WHERE comp2 CS 'd'. +ASSERT sy-tabix = 2. + +"--------- WHERE condition with predicate expressions --------- + +"Examples: IS [NOT] INITIAL +" IS [NOT] BOUND +" IS [NOT] INSTANCE OF + +READ TABLE itab INTO wa WHERE comp1 > 4 AND comp4 IS INITIAL. +ASSERT sy-tabix = 5. + +"--------- WITH KEY instead of WHERE condition --------- + +"Syntax warning in READ TABLE ... WHERE ... statements +READ TABLE itab INTO wa WHERE comp4 IS INITIAL. +ASSERT sy-tabix = 5. + +"For a better performance, the previous statement should be +"replaced by a READ TABLE ... WITH KEY ... statement. +READ TABLE itab INTO wa WITH KEY comp4 = ''. +ASSERT sy-tabix = 5. + +"You can also suppress the syntax warning by a pragma. +READ TABLE itab INTO wa WHERE comp4 IS INITIAL ##read_where_ok. +ASSERT sy-tabix = 5. + +"------------------- Further additions ------------------- + +"TRANSPORTING NO FIELDS addition is possible +READ TABLE itab TRANSPORTING NO FIELDS WHERE comp2 CS 'd'. +ASSERT sy-tabix = 2. + +"USING KEY addition +READ TABLE itab USING KEY primary_key INTO wa WHERE comp2 CS 't'. +ASSERT sy-tabix = 3. + +READ TABLE itab USING KEY sk INTO wa WHERE comp3 > 40. +ASSERT sy-tabix = 5. + +"------------------- Excursions ------------------- + +"Note the comparison rules for character-like data types +READ TABLE itab INTO wa WHERE comp2 = 'lorem' ##read_where_ok. +ASSERT sy-tabix = 1. + +"In the following case, the length of the comp2 value increased to match the +"length of the specified text field, i.e. the surplus characters from the right +"side text field are not truncated. As a consequence, the line is not found. + +DATA(some_text) = 'loremXYZ'. + +READ TABLE itab INTO wa WHERE comp2 = some_text ##read_where_ok. +ASSERT sy-tabix = 0 AND sy-subrc <> 0. + +"When using READ TABLE ... WITH KEY ... the behavior is different. In that +"case, the surplus characters are truncated because of a conversion. Therefore, +"the following statement finds a line. +READ TABLE itab INTO wa WITH KEY comp2 = some_text. +ASSERT sy-tabix = 1 AND sy-subrc = 0. + +"Note: The read target can only be placed before WHERE conditions. +"The following statements are not possible. +"READ TABLE itab WHERE comp2 CS 'd' INTO wa. +"READ TABLE itab WHERE comp2 CS 'd' TRANSPORTING NO FIELDS. + +"READ TABLE ... WHERE ... statements can replace LOOP AT ... WHERE ... +"statements including EXIT. +LOOP AT itab INTO wa WHERE comp2 CS 'd'. + ASSERT sy-tabix = 2. + EXIT. +ENDLOOP. + +"------------------- Dynamic WHERE condition ------------------- + +"Character-like data objects or standard tables with character-like line type +"can be specified + +DATA(dyn_where_cond_str) = `comp2 CS 'd'`. + +READ TABLE itab INTO wa WHERE (dyn_where_cond_str). +ASSERT sy-tabix = 2. + +DATA(dyn_where_cond_tab) = VALUE string_table( ( `comp2` ) ( `CS` ) ( `'d'` ) ). +READ TABLE itab INTO wa WHERE (dyn_where_cond_tab). +ASSERT sy-tabix = 2. +``` + +

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+ + #### COMPARING and TRANSPORTING Additions: Comparing Fields and Specifying Fields for Transport `... TRANSPORTING NO FIELDS`: It is only checked whether the line exists. No target area is specified. As mentioned above, the system fields are filled. @@ -3721,6 +3865,256 @@ ASSERT tabix = 5.

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+### Inserting and Deleting Lines in Internal Tables in Loops + +- In a loop, you can change the values of the current table line's components. You can also delete or insert entire lines. +- The position of these new or deleted lines is determined by the table index or a sorted key. For hashed tables or hash keys, the position is determined by the insertion order (though this can be changed with the `SORT` statement). +- After the currently processed table line, ... + - inserting a line: The new line is processed in the next loop pass (watch out for a non-terminating loop). + - deleting a line: The deleted line is not processed in the next loop pass. +- Before the currently processed table line, ... + - inserting a line: The internal loop counter (`sy-tabix`) increases accordingly (in the case of index tables, sorted keys). + - deleting a line: The internal loop counter (`sy-tabix`) decreases accordingly. +- You cannot replace or clear the entire table body in a loop. If detected statically, a syntax error is displayed. + +The following examples explore the insertion and deletion of lines when looping across internal tables: + +```abap +"Creating and populating a demo standard internal table to +"work with in the example loops +TYPES: BEGIN OF s_loop_mod, + text TYPE string, + num TYPE i, + END OF s_loop_mod, + t_loop_mod TYPE TABLE OF s_loop_mod WITH EMPTY KEY. + +"Inserting 10 entries into the demo table +DATA(itab_original) = VALUE t_loop_mod( FOR x = 1 WHILE x <= 10 ( text = x ) ). +DATA(itab) = itab_original. + +"---------- Inserting a line after the current line ---------- + +"The example inserts a line after the currently processed line +"using an INSERT statement and specifying the index value +"(sy-tabix value + 1). The 'num' component is assigned the +"current sy-tabix value. +"Note: In all statements, the sy-tabix value is stored in a +"variable right after the LOOP statement. Assume that multiple +"statements are included before the statement that actually uses +"the current sy-tabix value. Other statements that potentially +"change the sy-tabix value might interfere. +"An EXIT statement takes care of exiting the loop. In the example, +"all values of the 'num' component in the original table lines +"(except the first line) are initial as the loop is exited. +LOOP AT itab ASSIGNING FIELD-SYMBOL(). + DATA(tabix) = sy-tabix. + -num = tabix. + INSERT VALUE #( text = tabix ) INTO itab INDEX tabix + 1. + IF tabix = 50. + EXIT. + ENDIF. +ENDLOOP. + +*Internal table content (parts of it): +*TEXT NUM +*1 1 +*1 2 +*2 3 +*3 4 +*4 5 +*... +*48 49 +*49 50 +*50 0 +*2 0 +*3 0 +*4 0 +*... + +"---------- Deleting a line after the current line ---------- + +"The example deletes a line after the current line using a +"DELETE statement and the INDEX addition. The index value +"is specified using the current sy-tabix value + 1. +"The 'num' value in the resulting internal table includes +"the sy-tabix value. + +itab = itab_original. +LOOP AT itab ASSIGNING . + tabix = sy-tabix. + -num = tabix. + DELETE itab INDEX tabix + 1. +ENDLOOP. + +*Internal table content: +*TEXT NUM +*1 1 +*3 2 +*5 3 +*7 4 +*9 5 + +"---------- Inserting a line before the current line ---------- + +"The example insert a line before the currently processed line using +"an INSERT statement. The current sy-tabix value is used as INDEX value, +"moving down the currently processed table line one position. +"In that case, the sy-tabix value increases accordingly. +"Logic: +"- For example, the first line is processed, sy-tabix has the value 1. +"- A line is inserted at this position, moving down the currently processed line +" one position. The moved line is then in the second position (as a new line exists +" in the first position). +"- In the next loop pass, the loop is continued with the third line, i.e. +" sy-tabix has the value 3 in the second loop pass. +"The example includes modifications of the table components. The 'num' value +"is assigned the table index value after inserting the new line. The +"'num' value of existing table lines includes the value of the index before +"inserting the new line + 1. + +itab = itab_original. +FIELD-SYMBOLS TYPE s_loop_mod. +DATA new_line_counter TYPE i. +DATA tabix_copy TYPE i. + +LOOP AT itab ASSIGNING . + tabix = sy-tabix. + new_line_counter += 1. + + "Asserting that sy-tabix value has changed accordingly. + IF tabix <> 1. + ASSERT tabix = tabix_copy + 2. + ENDIF. + + DATA(new_line_text) = |---- New line { new_line_counter } ----|. + INSERT VALUE #( text = new_line_text ) INTO itab INDEX tabix ASSIGNING . + + DATA(idx_new) = line_index( itab[ text = new_line_text num = 0 ] ). + -num = idx_new. + + DATA(idx_existing) = line_index( itab[ text = -text num = 0 ] ). + DATA(new_text) = |{ -text }(existing line, index before insertion: { tabix })|. + -text = new_text. + -num = idx_existing. + + tabix_copy = tabix. +ENDLOOP. + +*Internal table content: +*TEXT NUM +*---- New line 1 ---- 1 +*1 (existing line, index before insertion: 1) 2 +*---- New line 2 ---- 3 +*2 (existing line, index before insertion: 3) 4 +*---- New line 3 ---- 5 +*3 (existing line, index before insertion: 5) 6 +*---- New line 4 ---- 7 +*4 (existing line, index before insertion: 7) 8 +*---- New line 5 ---- 9 +*5 (existing line, index before insertion: 9) 10 +*---- New line 6 ---- 11 +*6 (existing line, index before insertion: 11) 12 +*---- New line 7 ---- 13 +*7 (existing line, index before insertion: 13) 14 +*---- New line 8 ---- 15 +*8 (existing line, index before insertion: 15) 16 +*---- New line 9 ---- 17 +*9 (existing line, index before insertion: 17) 18 +*---- New line 10 ---- 19 +*10 (existing line, index before insertion: 19) 20 + + +"---------- Deleting a line before the current line ---------- + +"The example explores the deletion of a line before the currently +"processed line. The previous line in the table is deleted if +"the value of 'text' (an integer was inserted) is an even number. +"The DELETE statement specifies the index with the current sy-tabix +"value - 1. On deletion, the sy-tabix value is decreased accordingly. +"Before a potential deletion, the currently processed table line is +"copied to another table to visualize the current sy-tabix value in +"the 'num' component. + +itab = itab_original. +DATA itab_copy LIKE itab. + +LOOP AT itab ASSIGNING . + tabix = sy-tabix. + + -num = tabix. + INSERT INTO TABLE itab_copy. + + TRY. + IF CONV i( -text ) MOD 2 = 0. + DELETE itab INDEX tabix - 1. + ENDIF. + CATCH cx_sy_conversion_no_number . + ENDTRY. + +ENDLOOP. + +*Internal table content (itab): +*TEXT NUM +*2 2 +*4 3 +*6 4 +*8 5 +*10 6 + +*Internal table content (itab_copy): +*TEXT NUM +*1 1 +*2 2 +*3 2 +*4 3 +*5 3 +*6 4 +*7 4 +*8 5 +*9 5 +*10 6 + +"---------- Deleting the currently processed table line ---------- + +"The example explores deleting the currently processed table line using +"a string table. So, the DELETE statement specifies the current sy-tabix +"value for INDEX. In that case, the next line moves up one position, and +"the sy-tabix value remains the same, i.e. when sy-tabix is 2, and the +"line is deleted, the value remains 2 and processes the line moved up. + +"Creating and populating a demo internal table +DATA(str_tab) = VALUE string_table( ( `a` ) ( `#` ) ( `c` ) ( `#` ) ( `e` ) + ( `f` ) ( `g` ) ( `#` ) ( `i` ) ( `j` ) ). + +LOOP AT str_tab REFERENCE INTO DATA(dref). + tabix = sy-tabix. + IF dref->* CS `#`. + DELETE str_tab INDEX tabix. + ENDIF. +ENDLOOP. + +*Internal table content: +*a +*c +*e +*f +*g +*i +*j + +"---------- Statements clearing the entire internal table are not allowed in loops ---------- + +"The entire internal table cannot be deleted within loops. +"The following statements commented out are not possible. +LOOP AT str_tab REFERENCE INTO dref. + "CLEAR str_tab. + "str_tab = VALUE #( ). +ENDLOOP. +``` + +

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+ + ## Operations with Internal Tables Using ABAP SQL SELECT Statements ### Internal Tables as Target Data Objects in SELECT Queries diff --git a/06_Dynamic_Programming.md b/06_Dynamic_Programming.md index 1825748..0346bc5 100644 --- a/06_Dynamic_Programming.md +++ b/06_Dynamic_Programming.md @@ -1634,6 +1634,17 @@ IF sy-subrc <> 0. ... ENDIF. +"Specifying the WHERE condition dynamically +DATA(dyn_where_cond_str) = `col3 CS 'y'`. + +READ TABLE itab INTO DATA(dyn_res) WHERE (dyn_where_cond_str). +ASSERT sy-tabix = 2. + +DATA(dyn_where_cond_tab) = VALUE string_table( ( `col3` ) ( `CS` ) ( `'x'` ) ). + +READ TABLE itab INTO dyn_res WHERE (dyn_where_cond_tab). +ASSERT sy-tabix = 3. + "------------------------------------------------------------- "------------------------ Table expressions ------------------ "------------------------------------------------------------- diff --git a/README.md b/README.md index 924402e..097906a 100644 --- a/README.md +++ b/README.md @@ -222,7 +222,9 @@ Use the standalone version of the abapGit report to import the demo examples of ## ⚡ Known Issues - Only one user on the system can import this repository because all object names must be globally unique. - Regarding possible code check warnings, e.g. for the many strings in the code, not using an `ORDER BY` clause, or messages regarding using `SELECT *`, the code deliberately avoids [pragmas](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenpragma_glosry.htm) and [pseudo comments](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenpseudo_comment_glosry.htm) in order to focus on the available ABAP syntax. See also the [Disclaimer](#%EF%B8%8F-disclaimer). -- Regarding the examples to be imported into a system supporting classic ABAP, note the following: In most cases, the cheat sheet documents and examples focus on ABAP for Cloud Development. Therefore, the lower the [ABAP release](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenabap_release_glosry.htm) in your system, the fewer syntax options and examples are available. For example, the RAP examples need at least ABAP version 7.56. Or, the [`FINAL` declaration operator](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenfinal_inline.htm) is not available in ABAP version 7.56. The code examples in the classic ABAP branches do not necessarily reflect all (described) syntax variations and options that are available in classic ABAP and in the particular ABAP release. For more information on new ABAP features by release, see the [ABAP Release News (Standard ABAP)](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abennews.htm). +- Regarding the examples to be imported into a system supporting classic ABAP (where Standard ABAP is supported), note the following: In most cases, the cheat sheet documents and examples focus on ABAP for Cloud Development. Therefore, the lower the [ABAP release](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenabap_release_glosry.htm) in your system, the fewer syntax options and examples are available. For example, the RAP examples need at least ABAP version 7.56. Or, the [`FINAL` declaration operator](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenfinal_inline.htm) is not available in ABAP version 7.56. The code examples in the classic ABAP branches do not necessarily reflect all (described) syntax variations and options that are available in classic ABAP and in the particular ABAP release. For more information on new ABAP features by release, see the ABAP Release News: + - [ABAP Release News](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abennews.htm) for ABAP for Cloud Development. Note the ABAP release cycles listed there. + - For Standard ABAP, see the ABAP relese news [here](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abennews.htm). - If you encounter import problems with the XSLT/ST objects, try to manually paste the code from the 3 `...source.xml` files ([zdemo_abap_st_carrhtml](./src/zdemo_abap_st_carrhtml.xslt.source.xml), [zdemo_abap_st_strhtml](./src/zdemo_abap_st_strhtml.xslt.source.xml), [zdemo_abap_xslt_fl](./src/zdemo_abap_xslt_fl.xslt.source.xml)) into the improperly imported objects and activate all inactive objects.