DDL and DML Statements
The first method is for DDL statements such as
ALTER, whereas the second method is for the DML statements
Both methods have an obligatory input parameter STATEMENT of type
that must be passed to a syntactically correct SQL statement. The method EXECUTE_UPDATE also has a return value, ROWS_PROCESSED, that returns the number of table rows processed.
In DML statements, values passed to the database system can be given parameters using the placeholder
?. When the statement is executed, compatible ABAP Objects must be bound
to these parameters. This binding is made using the following methods of the class CL_SQL_STATEMENT, which expect a reference to an elementary, structured, or table-like data object and can be used as an alternative:
DELETE. It must be called exactly once before the SQL statement is executed. As with a structure, the components of the internal table are bound to the placeholders from left to right. The Native SQL interface converts the content of the table rows to appropriate bulk accesses, such as bulk inserts or bulk deletes.
After all SQL statements are executed, the binding is removed.
- The two methods EXECUTE_DDL and EXECUTE_UPDATE are technically different only in that EXECUTE_UPDATE returns the number of rows processed. However, for reasons of readability of the program it is advisable to only use the methods as intended.
- A data reference to an indicator variable of the predefined type INT2 in ABAP Dictionary can be passed to the optional input parameter IND_REF of the method SET_PARAM. If the value of this indicator variable is -1, the value 0 of a parameter on the database is converted to a null value.
- For security reasons, it is better to define the parameters of a DML statement using the placeholder
?rather than chaining dynamic content. This is also a way of preventing SQL injections. If the statement only contains static content from the program and dynamic content from outside the program is possible only in operand positions (using placeholders), the statement cannot be modified from outside.