Firebird 2.1 Language Reference Update

Example:
DDL statements
create global temporary table MyConnGTT (
id int not null primary key,
txt varchar(32),
ts timestamp default current_timestamp
)
on commit preserve rows;
commit;
create global temporary table MyTxGTT (
id int not null primary key,
parent_id int not null references MyConnGTT(id),
txt varchar(32),
ts timestamp default current_timestamp
);
commit;
Tip
In an existing database, it's not always easy to tell a regular table from a GTT, or a transaction-level GTT from
a connection-level GTT. Use this query to find out a table's type:
select t.rdb$type_name
from rdb$relations r
join rdb$types t on r.rdb$relation_type = t.rdb$type
where t.rdb$field_name = 'RDB$RELATION_TYPE'
and r.rdb$relation_name = 'TABLENAME'
Or, for an overview of all your relations:
select r.rdb$relation_name, t.rdb$type_name
from rdb$relations r
join rdb$types t on r.rdb$relation_type = t.rdb$type
where t.rdb$field_name = 'RDB$RELATION_TYPE'
and coalesce (r.rdb$system_flag, 0) = 0
GENERATED ALWAYS AS
Added in: 2.1
Description: Instead of COMPUTED [BY], you may also use the SQL-2003-compliant equivalent GENERATED
ALWAYS AS for computed fields.
Syntax:
Example:
colname [coltype] GENERATED ALWAYS AS (expression)
create table Persons (
id int primary key,
firstname varchar(24) not null,
middlename varchar(24),
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