Question

I would like to be able to support the following Sybase 15 ASE syntax in my unit/integration tests that use HSQL…

create table #myTable (value varchar(12) NULL)

HSQL won’t recognise how the temp table is named, and baulks at the # character. Instead HSQL would like to use something like this…

create temporary table myTable (value varchar(12) NULL)

or, HSQL also supports most of ANSI-92 SQL according to their docs, however Sybase ASE 15 doesn’t have great support for ANSI-92 SQL including how temporary tables are created so the following won’t work in Sybase but does in HSQL…

DECLARE LOCAL TEMPORARY TABLE mytable (value varchar(12) NULL)

From everything I have tried I cannot come up with a common syntax that will work with both Sybase and HSQL. Does anyone know of a clean way around this?

The only option I think I have is to create separate DAO’s for each database dialect, and control which one is used in the Spring Application Context XML files.

I don’t use Hibernate for my datasource, only Spring’s JdbcTemplate.

Answer 1

I chose to resolve this issue by implementing a couple of dialect helper classes for my DAO. My goals were to

1. Execute tests against HSQL databse instead of Sybase
2. Test as much of my production DAO as possible including the
   RowMapper and various SELECT/INSERT statements against the database schema as used in production (but implemented in HSQL)

My DAO ended up looking like this (note the DialectHelper being injected) …

@Repository
public class MyDaoJdbc MyDao {

    private DialectHelper dialectHelper;

    /* the meat of the DAO removed for clarity */

    @Override
    public void createTemporaryTable() {        
        getSimpleJdbcTemplate().update(dialectHelper.getTempTableCreateSql());
    }

    @Autowired
    public final void setDialectHelper(DialectHelper dialectHelper) {
        this.dialectHelper = dialectHelper;
    }
}

… my production Spring configuration (spring-db.xml) looks like this and injects the Sybase dialect

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
    <property name="driverClassName"    value="com.sybase.jdbc2.jdbc.SybDriver" />
    <property name="url"                    value="${jdbc.url}" />
    <property name="username"           value="${jdbc.username}" />
    <property name="password"           value="${jdbc.password}" />
</bean>

<bean id="dialectHelper" class="com.acme.myapp.jdbc.DialectHelperSybase" />

… and my Test Spring configuration (spring-db-test.xml) looks like this and injects the HSQL dialect

<jdbc:embedded-database id="dataSource" type="HSQL">
     <jdbc:script location="classpath:/resources/schema.sql"/>
     <jdbc:script location="classpath:/resources/test-data.sql"/>
</jdbc:embedded-database>

<bean id="dialectHelper" class="com.acme.myapp.dao.jdbc.DialectHelperHsql" />

The DialectHelper classes provide a way of separating out the incompatible database syntax from the DAO …

public class DialectHelperHsql implements DialectHelper {
    @Override
    public String getTempTableCreateSql() {
        return "create temporary table myTable (value varchar(12) NULL)";
    }
}

public class DialectHelperSybase implements DialectHelper {
    @Override
    public String getTempTableCreateSql() {
        return "create table #myTable (value varchar(12) NULL)";
    }
}

The Test class itself initialises Spring with the HSQL dialectHelper by loading the file spring-db-test.xml

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations={
    "classpath:resources/spring-context.xml",
    "classpath:resources/spring-db-test.xml"})
@Transactional
@TransactionConfiguration(defaultRollback = true)
public class MyDaoIntegrationHsqlTest {
    ...
}