その後、文字列リテラルや数値リテラルのSQLステートメントはもう認められません。これは、 WHERE NAME='abc' や WHERE CustomerId=10 といった形のSQLステートメントは失敗するという意味です。 PreparedStatementや上に記載されたパラメータは使用することができます。また、 リテラルの含まれないSQLステートメントと同様に、SQLステートメントを動的に生成したり、 APIステートメントを使用することも可能です。数値リテラルが許可されている二つ目のモードもあります: SET ALLOW_LITERALS NUMBERS 全てのリテラルを許可するには、 SET ALLOW_LITERALS ALL を実行します (これはデフォルトの設定です)。リテラルはadministratorのみによって使用可能、または使用不可になります。
#Afterwards, SQL statements with text and number literals are not allowed any more. That means, SQL statement of the form WHERE NAME='abc' or WHERE CustomerId=10 will fail. It is still possible to use PreparedStatements and parameters as described above. Also, it is still possible to generate SQL statements dynamically, and use the Statement API, as long as the SQL statements do not include literals. There is also a second mode where number literals are allowed: SET ALLOW_LITERALS NUMBERS. To allow all literals, execute SET ALLOW_LITERALS ALL (this is the default setting). Literals can only be enabled or disabled by an administrator.
#To connect to a database, a Java application first needs to load the database driver, and then get a connection. A simple way to do that is using the following code:
insert into test select x, '' from system_range(1, 10000);
-- fast
update test set name = 'y' where cast(id as varchar) like '1%';
-- slow
update test set name = 'x' where id in (select x from system_range(1, 10000) where cast(x as varchar) like '1%');
drop table test;
Optimize IN(...), IN(select), ID=? OR ID=?: create temp table and use join
Bug:
H2 1.0.62 (2007-11-25) has regressed on this query. Parser syntax error is returned (query is OK for derby, oracle, and earlier H2 versions).
SELECT COUNT(*) FROM (
SELECT TT.id,TT.table_name FROM (
SELECT DISTINCT id, table_name FROM information_schema.tables WHERE id=-8 UNION SELECT DISTINCT id, table_name FROM information_schema.tables WHERE id=-8) AS TT
) AS AWR WHERE AWR.id=-8
Remove the final predicate and the query parses & runs fine:
SELECT COUNT(*) FROM (
SELECT TT.id,TT.table_name FROM (
SELECT DISTINCT id, table_name FROM information_schema.tables WHERE id=-8 UNION SELECT DISTINCT id, table_name FROM information_schema.tables WHERE id=-8) AS TT
) AS AWR
toString: > the parameters for the prepared statements.
autocomplete only just after meaningful key (ctrl+space, space, bs, interpunctation, ...)
