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ABAP - Keyword Documentation → ABAP - Reference → Processing Internal Data → Internal Tables → Processing Statements for Internal Tables → READ TABLE itab →
READ TABLE - free_key
Syntax
... WITH KEY {
comp1 = operand1
comp2 = operand2 ... [BINARY SEARCH] }
| {
keyname COMPONENTS
comp1 = operand1 comp2 = operand2 ... } ...
Variants:
1. ... WITH KEY comp1 = operand1 comp2 = operand2 ... [BINARY SEARCH] ...
2. ... WITH KEY keyname COMPONENTS comp1 = operand1 comp2 = operand2 ... .
Effect
Specifies a free search key. The free search key can be defined freely or linked to the specification of a secondary table key in keyname.
Notes
... WITH KEY comp1 = operand1 comp2 = operand2 ... [BINARY SEARCH] ...
Addition:
Effect
Components comp1 comp2 ... can be specified as search keys after the addition WITH KEY, following the rules here. An operand operand1 operand2 ... is assigned to each of these search keys and must be compatible with the data type of the component (or convertible to this data type). No duplicate or overlapping key specifications can be made.
operand1 operand2 ... are general expression positions. If necessary, the content of the operands is converted to the data type of the components before the comparison. If an arithmetic expression is specified, the calculation type is determined from its operands and the data type of the component and the result, if necessary, is converted to the data type of the component.
The first row of the internal table is searched for whose values in the specified components (or their subareas or attributes) match the values in the assigned operands operand1 operand2 ...
The search runs as follows for the individual table categories, without BINARY SEARCH being specified:
If the name field of a component comp is initial, the first row that matches the search key is read. If all name fields are initial, the first row of the internal table is read.
When a row is found, the system field sy-tabix is set as specified by the table category:
If no row is found, sy-tabix is undefined (-1), except when the complete
table key or the addition BINARY SEARCH is specified in a sorted table. In
this case, sy-tabix is set to the row number of the entry in the primary
table index in front of which the row would be inserted using INSERT ... INDEX ..., to preserve the sort.
Notes
Example
The internal table html_viewer_tab contains references to HTML controls. The READ statement reads the reference that points to a HTML control in a specific container control.
DATA: container TYPE REF TO cl_gui_container,
html_viewer TYPE REF TO cl_gui_html_viewer.
DATA html_viewer_tab LIKE TABLE OF html_viewer WITH EMPTY KEY.
...
CREATE OBJECT html_viewer EXPORTING parent = container.
APPEND html_viewer TO html_viewer_tab.
...
READ TABLE html_viewer_tab
WITH KEY table_line->parent = container
INTO html_viewer.
...
... BINARY SEARCH
Effect
The addition BINARY SEARCH produces a binary search of the table, not linear. In the case of large tables (from approximately 100 entries), this can significantly reduce runtime. The table must, however, be sorted in ascending order by the components specified in the search key. The priority of the sort order must match exactly the order of the components in the search key. If this requirement is not met, the correct row is not usually found.
Notes
Example
Reads a table row with BINARY SEARCH after the table has been sorted accordingly. However, if possible sflight_tab should be created as a sorted table, or given a sorted secondary key afterwards (see example below).
DATA sflight_tab TYPE STANDARD TABLE OF sflight WITH EMPTY KEY.
...
SORT sflight_tab BY carrid connid fldate.
READ TABLE sflight_tab
WITH KEY carrid = '...' connid = '...' fldate = '...'
BINARY SEARCH
ASSIGNING FIELD-SYMBOL(<flight>).
... WITH KEY keyname COMPONENTS comp1 = operand1 comp2 = operand2 ...
Effect
keyname can be used to specify a table key. The same applies when specifying the components as in the variant without specifying keys.
If a secondary table key is specified in keyname, the behavior is as follows:
When a row is found, the system field sy-tabix is set with respect to the specified secondary table key:
If no row is found, sy-tabix is undefined (-1), except when it is covered in full by a sorted secondary key. In this case, sy-tabix is set to the row number of the entry in the secondary table index in front of which the row would be inserted using INSERT ... INDEX ..., to preserve the sort.
If the primary table
key is specified in keyname under the name primary_key, the behavior is the same as in the variant without keys specified.
Notes
Example
Reads a table row using the sorted secondary table key dbkey. The read is now performed automatically using a binary search (like the example above where BINARY SEARCH is specified explicitly) and an explicit sort is not necessary.
DATA sflight_tab TYPE STANDARD TABLE OF sflight WITH EMPTY KEY
WITH UNIQUE SORTED KEY dbkey
COMPONENTS carrid connid fldate.
...
READ TABLE sflight_tab WITH KEY dbkey
COMPONENTS carrid = '...' connid = '...' fldate = '...'
ASSIGNING FIELD-SYMBOL(<flight>).
Example
The DEMO_SECONDARY_KEYS program demonstrates the specification of a secondary table key compared to the completely free specification of a key and the resulting performance benefits.