/** Throws if the table is referenced in a foreign key constraint. */
private void checkTableIsReferenced(Table toDrop) throws HsqlException {
Constraint[] constraints = toDrop.getConstraints();
Constraint currentConstraint = null;
Table refTable = null;
boolean isRef = false;
boolean isSelfRef = false;
int refererIndex = -1;
for (int i = 0; i < constraints.length; i++) {
currentConstraint = constraints[i];
if (currentConstraint.getType() != Constraint.MAIN) {
continue;
}
refTable = currentConstraint.getRef();
isRef = (refTable != null);
isSelfRef = (isRef && toDrop.equals(refTable));
if (isRef && !isSelfRef) {
// cover the case where the referencing table
// may have already been dropped
for (int k = 0; k < tTable.size(); k++) {
if (refTable.equals(tTable.get(k))) {
refererIndex = k;
break;
}
}
if (refererIndex != -1) {
throw Trace.error(
Trace.TABLE_REFERENCED_CONSTRAINT,
Trace.Database_dropTable,
new Object[] {currentConstraint.getName().name, refTable.getName().name});
}
}
}
}
/**
* Drops the specified user-defined view or table from this Database object.
*
* <p>The process of dropping a table or view includes:
*
* <OL>
* <LI>checking that the specified Session's currently connected User has the right to perform
* this operation and refusing to proceed if not by throwing.
* <LI>checking for referential constraints that conflict with this operation and refusing to
* proceed if they exist by throwing.
* <LI>removing the specified Table from this Database object.
* <LI>removing any exported foreign keys Constraint objects held by any tables referenced by
* the table to be dropped. This is especially important so that the dropped Table ceases to
* be referenced, eventually allowing its full garbage collection.
* <LI>
* </OL>
*
* <p>
*
* @param name of the table or view to drop
* @param ifExists if true and if the Table to drop does not exist, fail silently, else throw
* @param isView true if the name argument refers to a View
* @param session the connected context in which to perform this operation
* @throws SQLException if any of the checks listed above fail
*/
void dropTable(String name, boolean ifExists, boolean isView, Session session)
throws SQLException {
Table toDrop = null;
int dropIndex = -1;
int refererIndex = -1;
Enumeration constraints = null;
Constraint currentConstraint = null;
Table refTable = null;
boolean isRef = false;
boolean isSelfRef = false;
for (int i = 0; i < tTable.size(); i++) {
toDrop = (Table) tTable.get(i);
if (toDrop.equals(name, session) && isView == toDrop.isView()) {
dropIndex = i;
break;
} else {
toDrop = null;
}
}
if (dropIndex == -1) {
if (ifExists) {
return;
} else {
throw Trace.error(isView ? Trace.VIEW_NOT_FOUND : Trace.TABLE_NOT_FOUND, name);
}
}
constraints = toDrop.getConstraints().elements();
while (constraints.hasMoreElements()) {
currentConstraint = (Constraint) constraints.nextElement();
if (currentConstraint.getType() != Constraint.MAIN) {
continue;
}
refTable = currentConstraint.getRef();
isRef = (refTable != null);
isSelfRef = (isRef && toDrop.equals(refTable));
if (isRef && !isSelfRef) {
// cover the case where the referencing table
// may have already been dropped
for (int k = 0; k < tTable.size(); k++) {
if (refTable.equals(tTable.get(k))) {
refererIndex = k;
break;
}
}
if (refererIndex != -1) {
// tony_lai@users 20020820 - patch 595156
throw Trace.error(
Trace.INTEGRITY_CONSTRAINT_VIOLATION,
currentConstraint.getName().name + " table: " + refTable.getName().name);
}
}
}
tTable.remove(dropIndex);
removeExportedKeys(toDrop);
aAccess.removeDbObject(toDrop.getName());
triggerNameList.removeOwner(toDrop.tableName);
indexNameList.removeOwner(toDrop.tableName);
toDrop.drop();
session.setScripting(!toDrop.isTemp());
session.commit();
}
