ALLBASE/SQL Reference Manual (36216-90216)

382 Chapter10
SQL Statements A - D
DELETE WHERE CURRENT
• If a referential constraint should be violated during processing of the DELETE
statement, the row is not deleted (unless error checking is deferred and the violation is
corrected before you COMMIT WORK). Refer to the discussion of the SET CONSTRAINTS
statement in this chapter for more information.
• A deletion from a table with a primary key (a referenced unique constraint) will fail if
any primary key row affected by the DELETE statement is currently referred to by some
referencing foreign key row. In order to delete such referenced rows, you must first
change the referencing foreign key rows to refer to other primary key rows, to contain a
NULL value in one of the foreign key columns, or to delete these referencing rows.
Alternatively, you can defer error checking (with the SET CONSTRAINT statement) and
fix the error later.
• The DELETE syntax is unchanged for use with LONG columns. When LONG data is
deleted, the space it occupied in the DBEnvironment is released when your transaction
ends. But the physical operating system data file created when you selected the long
field earlier still exists and you are responsible for removing it if you desire.
• A rule defined with a
StatementType of DELETE will affect DELETE WHERE CURRENT
statements performed on the rule's target table. When the DELETE WHERE CURRENT is
performed, each rule defined on that operation for the table is considered. If the rule
has no condition, it will fire and invoke its associated procedure with the specified
parameters on the current row. If the rule has a condition, it will evaluate the condition
and fire if the condition evaluates to TRUE and invoke the associated procedure with
the specified parameters on the current row. Invoking the procedure could cause other
rules, and thus other procedures, to be invoked if statements within the procedure
trigger other rules.
• If a DISABLE RULES statement is in effect, the DELETE WHERE CURRENT statement
will not fire any otherwise applicable rules. When a subsequent ENABLE RULES is
issued, applicable rules will fire again, but only for subsequent DELETE WHERE
CURRENT statements, not for those rows processed when rule firing was disabled.
• In a rule defined with a
StatementType of DELETE, any column reference in the
Condition or any ParameterValue will refer to the value of the column as it exists in
the database before it is removed by the DELETE WHERE CURRENT statement,
regardless of the use of
OldCorrelationName , TableName ,or NewCorrelationName
in the rule definition.
• When a rule is fired by this statement, the rule's procedure is invoked after the changes
have been made to the database for that row. The rule's procedure, and any chained
rules, will thus see the state of the database with the current partial execution of the
statement.
• If an error occurs during processing of any rule considered during execution of this
statement (including execution of any procedure invoked due to a rule firing), the
statement and any procedures invoked by any rules will have no effect. Nothing will
have been altered in the DBEnvironment as a result of this statement or the rules it
fired. Error messages are returned in the normal way.
Authorization
If you specify the name of a table, you must have DELETE or OWNER authority for that