@Override
public String getSQL() {
StatementBuilder buff = new StatementBuilder();
buff.append(Parser.quoteIdentifier(userAggregate.getName())).append('(');
for (Expression e : args) {
buff.appendExceptFirst(", ");
buff.append(e.getSQL());
}
return buff.append(')').toString();
}
// 调用了两次，一次在optimize，另一次在updateAggregate
private Aggregate getInstance() throws SQLException {
Aggregate agg = userAggregate.getInstance();
agg.init(userConnection);
return agg;
}