hxttdialect.java

hibernate连接access数据库,以及一些其他的hibernate介绍

     * Generate the appropriate select statement to to retreive the next value
     * of a sequence.
     * <p/>
     * This should be a "stand alone" select statement.
     *
     * @param sequenceName the name of the sequence
     * @return String The "nextval" select string.
     * @throws MappingException If sequences are not supported.
     */
    public final String getSequenceNextValString(String sequenceName) {
        //SELECT NEXTVAL('SEQUENCENAME')
        //"select next_value of " + sequenceName + " from system.onerow";
        return "select " + getSelectSequenceNextValString( sequenceName ) ;
    }
    
    /**
     * Generate the select expression fragment that will retreive the next
     * value of a sequence as part of another (typically DML) statement.
     * <p/>
     * This differs from {@link #getSequenceNextValString(String)} in that this
     * should return an expression usable within another statement.
     *
     * @param sequenceName the name of the sequence
     * @return The "nextval" fragment.
     * @throws MappingException If sequences are not supported.
     */
    public final String getSelectSequenceNextValString(String sequenceName) {
        return  "nextval('" + sequenceName+"')";
    }           
   
    /**
     * Typically dialects which support sequences can create a sequence
     * with a single command.  This is convenience form of
     * {@link #getCreateSequenceStrings} to help facilitate that.
     * <p/>
     * Dialects which support sequences and can create a sequence in a
     * single command need *only* override this method.  Dialects
     * which support sequences but require multiple commands to create
     * a sequence should instead override {@link #getCreateSequenceStrings}.
     *
     * @param sequenceName The name of the sequence
     * @return The sequence creation command
     * @throws MappingException If sequences are not supported.
     */
    public final String getCreateSequenceString(String sequenceName) {
        // create sequence if not exists userID start WITH 100 increment by 2 maxvalue 2000 cache 5 cycle;
        return "create sequence " + sequenceName;        
    }
    
    /**
     * Typically dialects which support sequences can drop a sequence
     * with a single command.  This is convenience form of
     * {@link #getDropSequenceStrings} to help facilitate that.
     * <p/>
     * Dialects which support sequences and can drop a sequence in a
     * single command need *only* override this method.  Dialects
     * which support sequences but require multiple commands to drop
     * a sequence should instead override {@link #getDropSequenceStrings}.
     *
     * @param sequenceName The name of the sequence
     * @return The sequence drop commands
     * @throws MappingException If sequences are not supported.
     */
    public final String getDropSequenceString(String sequenceName) {
        //drop sequence if exists userID;
        return "drop sequence " + sequenceName;
    }
    
    /**
     * Get the select command used retrieve the names of all sequences.
     *
     * @return The select command; or null if sequences are not supported.
     * @see org.hibernate.tool.hbm2ddl.SchemaUpdate
     */
    public final String getQuerySequencesString() {
        return null;
        //select sequence_name from domain.sequences";
        //"select sequence_schema || '.' || sequence_name from information_schema.ext_sequences";
    }
        
  
    // limit/offset support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    /**
     * Does this dialect support some form of limiting query results
     * via a SQL clause?
     *
     * @return True if this dialect supports some form of LIMIT.
     */
    public final boolean supportsLimit() {
        return true;//false;
    }

    /**
     * ANSI SQL defines the LIMIT clause to be in the form LIMIT offset, limit.
     * Does this dialect require us to bind the parameters in reverse order?
     *
     * @return true if the correct order is limit, offset
     */
    public final boolean bindLimitParametersInReverseOrder() {
        return true;//false;
    }

    // IDENTITY support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    /**
     * Does this dialect support identity column key generation?
     *
     * @return True if IDENTITY columns are supported; false otherwise.
     */
    public boolean supportsIdentityColumns() {
            return true;//false;
    }

    /**
     * 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;//false;//true;
    }*/


    
    /**
     * Get the select command to use to retrieve the last generated IDENTITY
     * value for a particuar table
     *
     * @param table The table into which the insert was done
     * @param column The PK column.
     * @param type The {@link java.sql.Types} type code.
     * @return The appropriate select command
     * @throws MappingException If IDENTITY generation is not supported.
     */
    public final String getIdentitySelectString(String table, String column, int type){
        //return getIdentitySelectString();
        return new StringBuffer().append("select currval('")
			.append(table)
			.append("','")
			.append(column)
			.append("')")
			.toString();
/*		return new StringBuffer().append("select currval('")
			.append(table)
			.append('_')
			.append(column)
			.append("_seq')")
			.toString();
 		return type==Types.BIGINT ?
			"select dbinfo('serial8') from systables where tabid=1" :
			"select dbinfo('sqlca.sqlerrd1') from systables where tabid=1";

 */
            
    }

    /**
     * Get the select command to use to retrieve the last generated IDENTITY
     * value.
     *
     * @return The appropriate select command
     * @throws MappingException If IDENTITY generation is not supported.
     */
/*    public String getIdentitySelectString() {
        //return "select last_insert_id()";
        return "select @@identity";
        //"select identity_val_local() from sysibm.sysdummy1"
        //call identity()"
        //"SELECT LAST_IDENTITY() FROM %TSQL_sys.snf";
    }*/

    /**
     * The syntax used during DDL to define a column as being an IDENTITY of
     * a particular type.
     *
     * @param type The {@link java.sql.Types} type code.
     * @return The appropriate DDL fragment.
     * @throws MappingException If IDENTITY generation is not supported.
     */
/*    public String getIdentityColumnString(int type) {
            return getIdentityColumnString();
/*		return type==Types.BIGINT ?
			"bigserial not null" :
			"serial not null";
 		return type==Types.BIGINT ?
			"serial8 not null" :
			"serial not null";

 * /
            
    }*/

    /**
     * The syntax used during DDL to define a column as being an IDENTITY.
     *
     * @return The appropriate DDL fragment.
     * @throws MappingException If IDENTITY generation is not supported.
     */
    public final String getIdentityColumnString() {
         return "not null auto_increment"; //starts with 1, implicitly
         //return "identity not null"; //starts with 1, implicitly
         //"autoincrement";
         //identity";
         //return "generated by default as identity (start with 1)"; //not null is implicit
    }


    /**
     * The keyword used to insert a generated value into an identity column (or null).
     * Need if the dialect does not support inserts that specify no column values.
     *
     * @return The appropriate keyword.
     */
    public final String getIdentityInsertString() {
        //return null;
        return "null";
    }
    
    // lock acquisition support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    /**
     * Does this dialect support <tt>FOR UPDATE</tt> in conjunction with
     * outer joined rows?
     *
     * @return True if outer joined rows can be locked via <tt>FOR UPDATE</tt>.
     */
    public final boolean supportsOuterJoinForUpdate() {
            return false;//true;//???