hxttdialect.java

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

    }
    
    
    // current timestamp support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    /**
     * Does this dialect support a way to retrieve the database's current
     * timestamp value?
     *
     * @return True if the current timestamp can be retrieved; false otherwise.
     */
    public final boolean supportsCurrentTimestampSelection() {
            return true;//false;
    }

    /**
     * Should the value returned by {@link #getCurrentTimestampSelectString}
     * be treated as callable.  Typically this indicates that JDBC escape
     * sytnax is being used...
     *
     * @return True if the {@link #getCurrentTimestampSelectString} return
     * is callable; false otherwise.
     */
    public final boolean isCurrentTimestampSelectStringCallable() {
            return true;//???
    }

    /**
     * Retrieve the command used to retrieve the current timestammp from the
     * database.
     *
     * @return The command.
     */
    public final String getCurrentTimestampSelectString() {
        return "select now()";
        //"select systimestamp from dual"
        //"select now()";
        //"call current_timestamp()"
    }
    
    /**
     * The name of the database-specific SQL function for retrieving the
     * current timestamp.
     *
     * @return The function name.
     */
    public final String getCurrentTimestampSQLFunctionName() {
        // the standard SQL function name is current_timestamp...
        return "now";//current_timestamp";
    }    
    
    // union subclass support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    /**
     * Does this dialect support UNION ALL, which is generally a faster
     * variant of UNION?
     *
     * @return True if UNION ALL is supported; false otherwise.
     */
    public final boolean supportsUnionAll() {
        return true;//false;
    }

    // miscellaneous support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~    
    
    /**
     * The fragment used to insert a row without specifying any column values.
     * This is not possible on some databases.
     *
     * @return The appropriate empty values clause.
     */
    public final String getNoColumnsInsertString() {
            return "values ( )";//???Doesn't support now.'
            //return "default values";
    }
    
    /**
     * The SQL literal value to which this database maps boolean values.
     *
     * @param bool The boolean value
     * @return The appropriate SQL literal.
     */
    public final String toBooleanValueString(boolean bool) {
        return bool ? "true" : "false";
    }    

    // DDL support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    /**
     * Do we need to drop constraints before dropping tables in this dialect?
     *
     * @return True if constraints must be dropped prior to dropping
     * the table; false otherwise.
     */
    public final boolean dropConstraints() {
            return false;//true;
    }
    
    /**
     * Do we need to qualify index names with the schema name?
     *
     * @return boolean
     */
    public final boolean qualifyIndexName() {
            return false;//true;
    }

    /**
     * The syntax used to add a column to a table (optional).
     *
     * @return The "add column" fragment.
     */
    public final String getAddColumnString() {
        //ALTER table TBNAME ADD COLUMN FIELDNAME FIELDTYPE
        return "add column";
    }

    public final String getDropForeignKeyString() {
        throw new UnsupportedOperationException("No drop foreign key foreign supported by Hxtt Dialect");
        //return " drop constraint ";
    }

    /**
     * The syntax used to add a primary key constraint to a table.
     *
     * @param constraintName The name of the PK constraint.
     * @return The "add PK" fragment
     */
    public final String getAddPrimaryKeyConstraintString(String constraintName) {
        return " primary key ";
        //return " add constraint " + constraintName + " primary key ";
    }
    
    
    /**
     * The keyword used to specify a nullable column.
     *
     * @return String
     */
    public final String getNullColumnString() {
        return " null";
    }

    public final boolean supportsIfExistsBeforeTableName() {
        return true;//false;
    }
    
    /**
     * Does this dialect support column-level check constraints?
     *
     * @return True if column-level CHECK constraints are supported; false
     * otherwise.
     */
    public final boolean supportsColumnCheck() {
        return false;//true;//Support little
    }

    /**
     * Does this dialect support table-level check constraints?
     *
     * @return True if table-level CHECK constraints are supported; false
     * otherwise.
     */
    public final boolean supportsTableCheck() {
        return false;//true;
    }
    
    public boolean supportsCascadeDelete() {
        return false;//true; HXTT Access supports
    }    
    
    /**
     * Is this dialect known to support what ANSI-SQL terms "row value
     * constructor" syntax; sometimes called tuple syntax.
     * <p/>
     * Basically, does it support syntax like
     * "... where (FIRST_NAME, LAST_NAME) = ('Steve', 'Ebersole') ...".
     *
     * @return True if this SQL dialect is known to support "row value
     * constructor" syntax; false otherwise.
     * @since 3.2
     */
    public final boolean supportsRowValueConstructorSyntax() {
        // return false here, as most databases do not properly support this construct...
        return true;//false;
    }
   
    /**
     * If the dialect supports {@link #supportsRowValueConstructorSyntax() row values},
     * does it offer such support in IN lists as well?
     * <p/>
     * For example, "... where (FIRST_NAME, LAST_NAME) IN ( (?, ?), (?, ?) ) ..."
     *
     * @return True if this SQL dialect is known to support "row value
     * constructor" syntax in the IN list; false otherwise.
     * @since 3.2
     */
    public final boolean supportsRowValueConstructorSyntaxInInList() {
            return true;//false;
    }

    /**
     * Should LOBs (both BLOB and CLOB) be bound using stream operations (i.e.
     * {@link java.sql.PreparedStatement#setBinaryStream}).
     *
     * @return True if BLOBs and CLOBs should be bound using stream operations.
     * @since 3.2
     */
    public final boolean useInputStreamToInsertBlob() {
            return false;//true;//???
    }
    

    /**
     * Does this dialect support definition of cascade delete constraints
     * which can cause circular chains?
     *
     * @return True if circular cascade delete constraints are supported; false
     * otherwise.
     * @since 3.2
     */
    public final boolean supportsCircularCascadeDeleteConstraints() {
            return false;//true; //??? MS Access doesn't support too?
    }
    
    
}