com.yqjr.framework.component.dialect.db.OracleDialect Maven / Gradle / Ivy

/**
 * Copyright © YQJR All rights reserved.
 */
package com.yqjr.framework.component.dialect.db;

/**
 * Oracle的方言实现
 * 
 * @author poplar.yfyang
 * @version 1.0 2010-10-10 下午12:31
 * @since JDK 1.5
 */
public class OracleDialect extends AbstractDialect {
	@Override
	public boolean supportsLimit() {
		return true;
	}

	@Override
	public String getLimitString(String sql, int offset, int limit) {
		return getLimitString(sql, offset, Integer.toString(offset), Integer.toString(limit));
	}

	/**
	 * 将sql变成分页sql语句,提供将offset及limit使用占位符号(placeholder)替换.
	 * 
	 * 	 * 如mysql
	 * dialect.getLimitString("select * from user", 12, ":offset",0,":limit") 将返回
	 * select * from user limit :offset,:limit
	 * 
	 *
	 * @param sql
	 *            实际SQL语句
	 * @param offset
	 *            分页开始纪录条数
	 * @param offsetPlaceholder
	 *            分页开始纪录条数－占位符号
	 * @param limitPlaceholder
	 *            分页纪录条数占位符号
	 * @return 包含占位符的分页sql
	 */
	public String getLimitString(String sql, int offset, String offsetPlaceholder, String limitPlaceholder) {
		sql = sql.trim();
		boolean isForUpdate = false;
		if (sql.toLowerCase().endsWith(" for update")) {
			sql = sql.substring(0, sql.length() - 11);
			isForUpdate = true;
		}
		StringBuilder pagingSelect = new StringBuilder(sql.length() + 100);

		if (offset > 0) {
			pagingSelect.append("select * from ( select row_.*, rownum rownum_ from ( ");
		} else {
			pagingSelect.append("select * from ( ");
		}
		pagingSelect.append(sql);
		if (offset > 0) {
			String endString = offsetPlaceholder + "+" + limitPlaceholder;
			pagingSelect.append(" ) row_ where rownum <= " + endString + ") where rownum_ > ")
					.append(offsetPlaceholder);
		} else {
			pagingSelect.append(" ) where rownum <= " + limitPlaceholder);
		}

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

		return pagingSelect.toString();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see com.yqjr.framework.component.dialect.Dialect#getDateFormat()
	 */
	@Override
	public DBDateInfo getDateFormat() {
		DBDateInfo dateInfo = new DBDateInfo("yyyy", "mm", "dd", "hh24", "mi", "ss");
		dateInfo.setToCharMethod("TO_CHAR");
		dateInfo.setToDateMethod("TO_DATE");
		dateInfo.setSysDateMethod("SYSDATE");
		return dateInfo;
	}

}