public void prepare() throws DatabaseException {
type = (String) cmd.getObject("type");
view_name = (String) cmd.getObject("view_name");
String schema_name = database.getCurrentSchema();
vname = TableName.resolve(schema_name, view_name);
vname = database.tryResolveCase(vname);
if (type.equals("create")) {
// Get the select expression
select_expression = (TableSelectExpression) cmd.getObject("select_expression");
// Get the column name list
ArrayList col_list = (ArrayList) cmd.getObject("column_list");
// Generate the TableExpressionFromSet hierarchy for the expression,
TableExpressionFromSet from_set = Planner.generateFromSet(select_expression, database);
// Form the plan
plan = Planner.formQueryPlan(database, select_expression, from_set, new ArrayList());
// Wrap the result around a SubsetNode to alias the columns in the
// table correctly for this view.
int sz = (col_list == null) ? 0 : col_list.size();
Variable[] original_vars = from_set.generateResolvedVariableList();
Variable[] new_column_vars = new Variable[original_vars.length];
if (sz > 0) {
if (sz != original_vars.length) {
throw new StatementException("Column list is not the same size as the columns selected.");
}
for (int i = 0; i < sz; ++i) {
String col_name = (String) col_list.get(i);
new_column_vars[i] = new Variable(vname, col_name);
}
} else {
sz = original_vars.length;
for (int i = 0; i < sz; ++i) {
new_column_vars[i] = new Variable(vname, original_vars[i].getName());
}
}
// Check there are no repeat column names in the table.
for (int i = 0; i < sz; ++i) {
Variable cur_v = new_column_vars[i];
for (int n = i + 1; n < sz; ++n) {
if (new_column_vars[n].equals(cur_v)) {
throw new DatabaseException(
"Duplicate column name '"
+ cur_v
+ "' in view. "
+ "A view may not contain duplicate column names.");
}
}
}
// Wrap the plan around a SubsetNode plan
plan = new QueryPlan.SubsetNode(plan, original_vars, new_column_vars);
}
}
public Table evaluate() throws DatabaseException {
DatabaseQueryContext context = new DatabaseQueryContext(database);
if (type.equals("create")) {
// Does the user have privs to create this tables?
if (!database.getDatabase().canUserCreateTableObject(context, user, vname)) {
throw new UserAccessException("User not permitted to create view: " + view_name);
}
// Does the schema exist?
boolean ignore_case = database.isInCaseInsensitiveMode();
SchemaDef schema = database.resolveSchemaCase(vname.getSchema(), ignore_case);
if (schema == null) {
throw new DatabaseException("Schema '" + vname.getSchema() + "' doesn't exist.");
} else {
vname = new TableName(schema.getName(), vname.getName());
}
// Check the permissions for this user to select from the tables in the
// given plan.
Select.checkUserSelectPermissions(context, user, plan);
// Does the table already exist?
if (database.tableExists(vname)) {
throw new DatabaseException("View or table with name '" + vname + "' already exists.");
}
// Before evaluation, make a clone of the plan,
QueryPlanNode plan_copy;
try {
plan_copy = (QueryPlanNode) plan.clone();
} catch (CloneNotSupportedException e) {
Debug().writeException(e);
throw new DatabaseException("Clone error: " + e.getMessage());
}
// We have to execute the plan to get the DataTableDef that represents the
// result of the view execution.
Table t = plan.evaluate(context);
DataTableDef data_table_def = new DataTableDef(t.getDataTableDef());
data_table_def.setTableName(vname);
// Create a ViewDef object,
ViewDef view_def = new ViewDef(data_table_def, plan_copy);
// And create the view object,
database.createView(query, view_def);
// The initial grants for a view is to give the user who created it
// full access.
database
.getGrantManager()
.addGrant(
Privileges.TABLE_ALL_PRIVS,
GrantManager.TABLE,
vname.toString(),
user.getUserName(),
true,
Database.INTERNAL_SECURE_USERNAME);
} else if (type.equals("drop")) {
// Does the user have privs to drop this tables?
if (!database.getDatabase().canUserDropTableObject(context, user, vname)) {
throw new UserAccessException("User not permitted to drop view: " + view_name);
}
// Drop the view object
database.dropView(vname);
// Drop the grants for this object
database.getGrantManager().revokeAllGrantsOnObject(GrantManager.TABLE, vname.toString());
} else {
throw new Error("Unknown view command type: " + type);
}
return FunctionTable.resultTable(context, 0);
}