dialect.java

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	 * The default implementation (in this class) returns null.
	 * @param insertSQL a parameterized SQL statement to insert a row into a table.
	 * @return a SQL statement that has the same effect as insertSQL
	 * and also gets the identifier of the inserted row.
	 * Return <code>null</code> if this dialect doesn't support this feature.
	 */
	public String appendIdentitySelectToInsert(String insertSQL) {
		return null;
	}
	
	/**
	 * The syntax that returns the identity value of the last insert, if
	 * identity column key generation is supported.
	 * @throws MappingException if no native key generation
	 */
	public String getIdentitySelectString() throws MappingException {
		throw new MappingException("Dialect does not support identity key generation");
	}
	/**
	 * The keyword used to specify an identity column, if identity 
	 * column key generation is supported.
	 * @throws MappingException if no native key generation
	 */
	public String getIdentityColumnString() throws MappingException {
		throw new MappingException("Dialect does not support identity key generation");
	}
	/**
	 * The keyword used to insert a generated value into an identity column (or null)
	 * @return String
	 */
	public String getIdentityInsertString() {
		return null;
	}
	/**
	 * The keyword used to insert a row without specifying any column values
	 */
	public String getNoColumnsInsertString() {
		return "values ( )";
	}
	/**
	 * The syntax that fetches the next value of a sequence, if sequences are supported.
	 * @param sequenceName the name of the sequence
	 * @return String
	 * @throws MappingException if no sequences
	 */
	public String getSequenceNextValString(String sequenceName) throws MappingException {
		throw new MappingException("Dialect does not support sequences");
	}
	/**
	 * The syntax used to create a sequence, if sequences are supported.
	 * @param sequenceName the name of the sequence
	 * @return String
	 * @throws MappingException if no sequences
	 */
	public String getCreateSequenceString(String sequenceName) throws MappingException {
		throw new MappingException("Dialect does not support sequences");
	}
	/**
	 * The syntax used to drop a sequence, if sequences are supported.
	 * @param sequenceName the name of the sequence
	 * @return String
	 * @throws MappingException if no sequences
	 */
	public String getDropSequenceString(String sequenceName) throws MappingException {
		throw new MappingException("Dialect does not support sequences");
	}
	/**
	 * A query used to find all sequences
	 * @see net.sf.hibernate.tool.hbm2ddl.SchemaUpdate
	 */
	public String getQuerySequencesString() {
		return null;
	}
	
	/**
	 * Get the <tt>Dialect</tt> specified by the current <tt>System</tt> properties.
	 * @return Dialect
	 * @throws HibernateException
	 */
	public static Dialect getDialect() throws HibernateException {
		String dialectName = Environment.getProperties().getProperty(Environment.DIALECT);
		if (dialectName==null) throw new HibernateException("The dialect was not set. Set the property hibernate.dialect.");
		try {
			return (Dialect) ReflectHelper.classForName(dialectName).newInstance();
		}
		catch (ClassNotFoundException cnfe) {
			throw new HibernateException("Dialect class not found: " + dialectName);
		}
		catch (Exception e) {
			throw new HibernateException( "Could not instantiate dialect class", e );
		}
	}
	
	
	/**
	 * Get the <tt>Dialect</tt> specified by the given properties or system properties.
	 * @param props
	 * @return Dialect
	 * @throws HibernateException
	 */
	public static Dialect getDialect(Properties props) throws HibernateException {
		String dialectName = props.getProperty(Environment.DIALECT);
		if (dialectName== null) return getDialect();
		try {
			return (Dialect) ReflectHelper.classForName(dialectName).newInstance();
		}
		catch (ClassNotFoundException cnfe) {
			throw new HibernateException("Dialect class not found: " + dialectName);
		}
		catch (Exception e) {
			throw new HibernateException( "Could not instantiate dialect class", e );
		}
	}
	
	/**
	 * Retrieve a set of default Hibernate properties for this database.
	 * @return a set of Hibernate properties
	 */
	public final Properties getDefaultProperties() {
		return properties;
	}
	
	/**
	 * Completely optional cascading drop clause
	 * @return String
	 */
	public String getCascadeConstraintsString() {
		return StringHelper.EMPTY_STRING;
	}
	
	/**
	 * Create an <tt>OuterJoinGenerator</tt> for this dialect.
	 * @return OuterJoinGenerator
	 */
	public JoinFragment createOuterJoinFragment() {
		return new ANSIJoinFragment();
	}
	
	/**
	 * Create a <tt>CaseFragment</tt> for this dialect.
	 * @return OuterJoinGenerator
	 */
	public CaseFragment createCaseFragment() {
		return new ANSICaseFragment();
	}
	
	/**
	 * The name of the SQL function that transforms a string to 
	 * lowercase
	 * 
	 * @return String
	 */
	public String getLowercaseFunction() {
		return "lower";
	}
	
	/**
	 * Does this <tt>Dialect</tt> have some kind of <tt>LIMIT</tt> syntax?
	 */
	public boolean supportsLimit() {
		return false;
	}
	
	/**
	 * Does this dialect support an offset?
	 */
	public boolean supportsLimitOffset() {
		return supportsLimit();
	}
	
	/**
	 * Add a <tt>LIMIT</tt> clause to the given SQL <tt>SELECT</tt>
	 * @return the modified SQL
	 */
	public String getLimitString(String querySelect, boolean hasOffset) {
		throw new UnsupportedOperationException("paged queries not supported");
	}
	
	public String getLimitString(String querySelect, boolean hasOffset, int limit) {
		return getLimitString(querySelect, hasOffset);
	}
	public boolean supportsVariableLimit() {
		return supportsLimit();
	}
	
	/**
	 * Does the <tt>LIMIT</tt> clause specify arguments in the "reverse" order
	 * limit, offset instead of offset, limit?
	 * @return true if the correct order is limit, offset
	 */
	public boolean bindLimitParametersInReverseOrder() {
		return false;
	}
	
	/**
	 * Does the <tt>LIMIT</tt> clause come at the start of the
	 * <tt>SELECT</tt> statement, rather than at the end?
	 * @return true if limit parameters should come before other parameters
	 */
	public boolean bindLimitParametersFirst() {
		return false;
	}
	
	/**
	 * Does the <tt>LIMIT</tt> clause take a "maximum" row number instead
	 * of a total number of returned rows?
	 */
	public boolean useMaxForLimit() {
		return false;
	}
	
	/**
	 * The opening quote for a quoted identifier
	 */
	public char openQuote() {
		return '"';
	}
	
	/**
	 * The closing quote for a quoted identifier
	 */
	public char closeQuote() {
		return '"';
	}

	/**
	 * SQL functions as defined in general. The results of this
	 * method should be integrated with the specialisation's data.
	 */
	public final Map getFunctions() {
		return sqlFunctions;
	}
	
	public boolean supportsIfExistsBeforeTableName() {
		return false;
	}
	
	public boolean supportsIfExistsAfterTableName() {
		return false;
	}
	
	/**
	 * The seperator between the schema/tablespace name and the table name.
	 */
	public char getSchemaSeperator(){
		return StringHelper.DOT;
	}
	
	/**
	 * Does this dialect support check constraints?
	 */
	public boolean supportsCheck() {
		return true;
	}

	/**
	 * Whether this dialect have an Identity clause added to the data type or a 
	 * completely seperate identity data type
	 * @return boolean
	 */
	public boolean hasDataTypeInIdentityColumn() {
		return true;
	}
}