hxttaccessdialect.java

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

package com.hxtt.support.hibernate;

import java.sql.Types;


/**
 * An SQL dialect for HXTT Access.
 */
public class HxttAccessDialect  extends HxttDialect {

    public HxttAccessDialect() {
        super();
        //complete map
        registerColumnType( Types.BIT, "boolean" );
        registerColumnType(Types.CHAR, "char(l)");
        registerColumnType( Types.VARCHAR, "varchar($l)" );
        //registerColumnType(Types.VARCHAR, 255, "varchar($l)");
        registerColumnType(Types.LONGVARCHAR, "longvarchar");
        registerColumnType(Types.NUMERIC, "numeric($p,$s)");
        registerColumnType(Types.BOOLEAN, "boolean");
        registerColumnType( Types.BIGINT, "bigint");//numeric(19,0)" );  // MS Access DON'T SUPPORT BIGINT
        registerColumnType(Types.TINYINT, "tinyint"); //HXTT Access' tinyint is from 0 to 255
        registerColumnType(Types.SMALLINT, "smallint");
        registerColumnType(Types.INTEGER, "integer");
        registerColumnType(Types.REAL, "real");
        registerColumnType( Types.FLOAT, "float" ); // HXTT Access DON'T SUPPORT FLOAT ,it will be a double type
        registerColumnType(Types.DOUBLE, "double");
        registerColumnType( Types.BINARY, 255, "binary" );
        registerColumnType(Types.VARBINARY, 255, "varbinary");
        registerColumnType( Types.LONGVARBINARY, "longvarbinary");

        registerColumnType( Types.DATE, "date" );
        registerColumnType( Types.TIME, "time" );   //  HXTT Access DON'T SUPPORT TIME
        registerColumnType(Types.TIMESTAMP, "timestamp");
        registerColumnType( Types.BLOB, "blob" ); // BLOB COLUMN WILL CHANGE TO  JAVA_OBJECT TYPE COLUMN
        registerColumnType( Types.CLOB, "clob" ); // CLOB COLUMN WILL CHANGE TO  LONGVARCHAR TYPE COLUMN
        registerColumnType(Types.OTHER, "currency");
        //registerColumnType( Types.OTHER, "graphics" );
        registerColumnType(Types.OTHER, "ole");
        registerColumnType( Types.JAVA_OBJECT, "java_object" );

    }


    /**
     * Apply s limit clause to the query.
     * <p/>
     * Typically dialects utilize {@link #supportsVariableLimit() variable}
     * limit caluses when they support limits.  Thus, when building the
     * select command we do not actually need to know the limit or the offest
     * since we will just be using placeholders.
     * <p/>
     * Here we do still pass along whether or not an offset was specified
     * so that dialects not supporting offsets can generate proper exceptions.
     * In general, dialects will override one or the other of this method and
     * {@link #getLimitString(String, int, int)}.
     *
     * @param query The query to which to apply the limit.
     * @param hasOffset Is the query requesting an offset?
     * @return the modified SQL
     */
    public String getLimitString(String sql, boolean hasOffset) {
/*        return new StringBuffer(sql.length() + 20)
            .append(sql)
            .append(hasOffset ? " limit ?, ?" : " limit ?")
            .toString();*/

        sql = sql.trim();
        boolean isForUpdate = false;
        if ( sql.toLowerCase().endsWith(" for update") ) {
            sql = sql.substring( 0, sql.length()-11 );
            isForUpdate = true;
        }

        StringBuffer pagingSelect = new StringBuffer( sql.length()+100 );
        if (hasOffset) {
            pagingSelect.append("select * from ( select row_.*, RECNO() rownum_ from ( ");
        }
        else {
            pagingSelect.append("select * from ( ");
        }
        pagingSelect.append(sql);
        if (hasOffset) {
            pagingSelect.append(" ) row_ where RECNO() <= ?) where rownum_ > ?");
        }
        else {
            pagingSelect.append(" ) where RECNO() <= ?");
        }

        if (isForUpdate) pagingSelect.append(" for update");

        return pagingSelect.toString();
    }




    public boolean supportsCascadeDelete() {
        return true;//false;
    }
    
    
    
}