* #3848 Fix regression for Sql Server and Oracle with exists() introduced in 18.2.0
Fix#3848: exists() generates invalid scalar SQL on SQL Server and Oracle
Query.exists() generated `select exists(<subquery>)`, which is valid on
Postgres/H2/MySQL but rejected by SQL Server and Oracle since both only
support EXISTS as a predicate, not as a directly selectable scalar boolean
expression. ┃
┃
Add DatabasePlatform.existsWithCaseWhen/existsFromClause capability flags
and use them in CQueryBuilder.wrapSelectExists() to generate
`select case when exists(<subquery>) then 1 else 0 end` on platforms that ┃
need it, with an additional ` from dual` suffix for Oracle (which requires ┃
a FROM clause on every select). CQueryExists reads the boolean result via ┃
ResultSet.getBoolean(1), which correctly interprets the resulting 0/1 int.
* Fix tests TestInsertCheckUnique for Oracle and SQL Server
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Co-authored-by: robin.bygrave <robin.bygrave@eroad.com>
So DatabaseBuilder.Settings has all the getters for code looking to read
the configuration that has been set. So DatabaseBuilder now just has the
setter methods.
Use DatabaseBuilder.settings() to access the settings and read the config
that has been set.
In theory no is customising these classes and probably should have their own copy of them if
they are doing do. Thus making these types final and package protected.
