常用数据库转换语句
以下是管理访问SQL函数，各数据库差异的函数 由于不同数据库其Sql函数不同，这里用函数封装了这种差异：
/** * instr字符替换脚本(列名)，暂时只支持iEnd为1的SQL Server脚本 * * @param sStr1 * oracle中为要搜索的表达式，SQL Server中为搜索表达式 * @param sStr2 * SQL Server中为要搜索的表达式，oracle中为搜索表达式 * @param iStart * 开始位置 * @param iEnd * 仅在Oracle中起作用 * @return */ public String sqlInstr(String sStr1, String sStr2, int iStart, int iEnd) { if (dbType == DB_ORA) return "instr(" + sStr1 + "," + sStr2 + "," + iStart + "," + iEnd + ")"; if (dbType == DB_SQL) { if (iStart < 0) { sStr1 = "REPLACE(REVERSE(" + sStr2 + "),REVERSE(" + sStr1 + ")," + sStr1 + ")"; } return "charindex(" + sStr2 + "," + sStr1 + " ,ABS(" + iStart + "))"; } if (dbType == DB_DB2) return "POSSTR(" + sStr1 + "," + sStr2 + ")";// db2不支持sStart return ""; }
/**
* 把字符串转成日期格式 YYYY[token]MM[token]DD
*
* @param _stringDate
* @return
*/
public String sqlFormatStringToDate(String _stringDate, String token) {
String sql = "";
if (dbType == DB_ORA) {
sql += "TO_date('" + _stringDate + "','YYYY" + token + "MM" + token
+ "DD')";
} else if (dbType == DB_SQL) {
sql += "convert(datetime,'" + _stringDate+"')";
} else if (dbType == DB_DB2) {
sql += "TO_date('" + _stringDate + "','YYYY" + token + "MM" + token
+ "DD')";
} else {
// ERROR
}
return sql;
}
/**
* 日期函数转换（处理列名）
*
* @param strColName
* 要转换的列名或日期类型数据
* @param sFormat
* 要转换的格式
* @param isColName
* 标识是否是列名
* @return 返回字符串类型
*/
public String sqlDateS(String strColName, String sFormat, boolean isColName) {
if (isColName) {
if (dbType == DB_ORA) {
return "to_char(" + strColName + ",'" + sFormat + "')";
} else if (dbType == DB_SQL)
return "CONVERT(VARCHAR(" + sFormat.length() + "),"
+ strColName + ",112)";
else if (dbType == DB_DB2)
return "cast(" + strColName + " as VARCHAR(10))";
} else {
return sqlDateS(strColName, sFormat);
}
return "";
}
/**
* 将字符列转为日期类型
*
* @param strColName
* 要转换的列名或日期类型数据
* @param sFormat
* 要转换的格式
* @param isColName
* 标识是否是列名
* @return 返回字符串类型
*/
public String sqlSColToDate(String strColName, String sFormat) {
if (dbType == DB_ORA) {
return "to_date(" + strColName + ",'" + sFormat + "')";
} else if (dbType == DB_SQL) {
return "cast(" + strColName + " as DateTime)";
} else if (dbType == DB_DB2) {
return "cast(" + strColName + " as DateTime)";
}
return "";
}
/**
* 把字段或日期转成token格式
*
* @param date
* @return
*/
public String sqlFormatDate(String date, String token) {
String SQL = "";
if (dbType == DB_ORA) {
SQL += "TO_CHAR(" + date + ",'YYYY" + token
+ "MM" + token + "DD')";
} else if (dbType == DB_SQL) {
if (token == "") {
SQL += "convert(varchar(120),convert(datetime," + date
+ ") ,112)";
} else if (token == "/") {
SQL += "convert(varchar(120),convert(datetime," + date
+ ") ,111)";
} else if (token == "-") {
SQL += "convert(varchar(120),convert(datetime," + date
+ ") ,120)";
} else {
SQL += "convert(varchar(120),convert(datetime," + date
+ ") ,112)";
}
} else if (dbType == DB_DB2) {
SQL += "TO_CHAR(" + date + ",'YYYY" + token
+ "MM" + token + "DD')";
} else {
// ERROR
}
return SQL;
}
public String sqlFToDate (String date,String token)
{
String SQL = "";
if (dbType == DB_ORA) {
SQL += "to_date('" + date + "')";
} else if (dbType == DB_SQL) {
SQL += "convert(datetime,'" + date
+ "')";
} else if (dbType == DB_DB2) {
SQL += "to_date('" + date + "')";
} else {
// ERROR
}
return SQL;
/*
* 处理自增列
*/
public String SQLSEQUENCE(String que) {
if (dbType == DB_ORA)
return que + ".nextval, ";
else if (dbType == DB_SQL) {
return "";
} else if (dbType == DB_DB2)
return "NEXTVAL FOR " + que + ",";
return "";
}
/**
* 按日期返回星期几
*
* @param date
* @return
* @throws YssException
*/
public String getWeek(String date) throws YssException {
// date=sqlDateS(date,"yyyy-mm-dd");
if (dbType == DB_ORA)
return "to_char(" + date + ",'d')";
else if (dbType == DB_SQL)
return "DATEPART(wk," + date + ")";
else if (dbType == DB_DB2)
return "DAYOFWEEK(" + date + ")";
else
throw new YssException("数据库类型异常！");
}
/**
* 求指定日期在一年中是第几周
*
* @param date
* @return
* @throws YssException
*/
public String getWeekth(String date) throws YssException {
// date=sqlDateS(date,"yyyy-mm-dd");
if (dbType == DB_ORA)
return "to_char(" + date + ",'IW')";
else if (dbType == DB_SQL) {
return "DATEPART(week," + date + ")";
} else if (dbType == DB_DB2)
return "WEEK(" + date + ")";
else
throw new YssException("数据库类型异常！");
}
/**
* 日期在加减时不同数据库的处理
*
* @return
* @throws YssException
*/
public String getDay() throws YssException {
// date=sqlDateS(date,"yyyy-mm-dd");
if (dbType == DB_ORA)
return "+0";
else if (dbType == DB_SQL)
return "+0";
else if (dbType == DB_DB2)
return "day";
else
throw new YssException("数据库类型异常！");
}
/**
* 取日期的年份
*
* @param date
* @return
* @throws YssException
*/
public String getYear(String date) throws YssException {
// date=sqlDateS(date,"yyyy-mm-dd");
if (dbType == DB_ORA) {
Pattern p = Pattern.compile("^\\d{4}[-]{1}\\d{1,2}[-]{1}\\d{1,2}$");
Matcher m = p.matcher(date);// 正则匹配
if (m.matches())
return "to_number(to_char(to_date('" + date
+ "','yyyy-mm-dd'),'yyyy'))";
else
return "to_number(to_char(" + date + ",'yyyy'))";
} else if (dbType == DB_SQL)
return "DATENAME(year," + date + ")";
else if (dbType == DB_DB2)
return "YEAR(" + date + ")";
else
throw new YssException("数据库类型异常！");
}
/** 取模 */
public String sqlMod(String sStr1, String sStr2, boolean bAbs) {
if (dbType == DB_ORA)
return (bAbs ? "abs(" : "") + "mod(" + sStr1 + "," + sStr2 + ")"
+ (bAbs ? ")" : "");
if (dbType == DB_SQL)
return (bAbs ? "abs(" : "") + "(" + sStr1 + ") % (" + sStr2 + ")"
+ (bAbs ? ")" : "");
return (bAbs ? "abs(" : "") + "mod(" + sStr1 + ", " + sStr2 + ")"
+ (bAbs ? ")" : "");
}
/** sqlTrim */
public String sqlTrim(String sStr) {
if (dbType == DB_ORA)
return "Trim(" + sStr + ")";
else
return "RTrim(LTrim(" + sStr + "))";
}
/**
* 参看Oracle的NVL(Sqlserver的isnull)函数
*/
public String sqlIsNull(String str1, String str2) {
if (dbType == DB_ORA)
return "NVL(" + str1 + "," + str2 + ")";
if (dbType == DB_SQL)
return "IsNull(" + str1 + "," + str2 + ")";
return "(case when " + str1 + " is null then " + str2 + " else " + str1
+ " end)";
}
public String sqlIsNull(String str1) {
return sqlIsNull(str1, "0");
}
// 取整 (截取) 2008-8-2
public String sqlInt(String str) {
if (dbType == DB_SQL) {
return "cast(" + str + " as int)";
} else {
return "trunc(" + str + ")";
}
}
// cxd 20090108把字符转换成double
public String sqlDouble(String str) {
if (dbType == DB_SQL) {
return "cast(" + str + " as numeric(18,4))";
}
if (dbType == DB_DB2) {
return "cast(" + str + " as decimal(17,4))";
} else
return "trunc(" + str + ",4)";
}
/**
* '整除和取模,sstr1和sstr2是整数表达式
*/
public String sqlIntDiv(String sStr1, String sStr2, boolean bAbs) {
if (dbType == DB_ORA)
return "floor(abs("
+ sStr1
+ ")/abs("
+ sStr2
+ ")) "
+ (bAbs ? ""
: ("* sign(" + sStr1 + ") * sign(" + sStr2 + ")"));
return (bAbs ? "abs(" : "") + "(" + sStr1 + ") / (" + sStr2 + ")"
+ (bAbs ? ")" : "");
}
/**
* 取日期年、月、日
*
* @param cloumnname
* String
* @param i
* int 取年份时i从1开始
* @param j
* int
* @return String
*/
public String sqlSubstr(String cloumn_date, int i, int j) {
String ss = "";
if (dbType == DB_ORA)// ora 中取年份时可以从0-4 也可以从1-4
ss = "subStr(to_char(" + cloumn_date + ",'yyyy-mm-dd')," + i + ","
+ j + ")";
else if (dbType == DB_DB2)// db2 中只能从1-4
ss = "subStr(char(" + cloumn_date + ")," + i + "," + j + ")";
else
ss = "SUBSTRING(CONVERT(VARCHAR(10)," + cloumn_date + ",120)," + i
+ "," + j + ")";
return ss;
}
/**
* 日期加减天数
*
* @param sDate
* String：日期，如果是字符串字段，则要调用函数转换成sql日期
* @param sDays
* String：天数
* @return String
*/
public String sqlDateAdd(String sDate, String sDays) {
if (dbType == DB_DB2) {
return sDate + " " + sDays + " days ";
} else if (dbType == DB_ORA) {
return ("to_char(to_date('" + sDate + "','"
+ YssCons.YSS_DATEFORMAT + "')" + sDays + ")");
// return sDate + " " + sDays;
} else {// DATEADD (day,-1,fdate)
return ("DATEADD (day," + sDays + "," + sDate + ")");
}
}
/**
* 日期相减
*
* @param sDate1
* String：日期1，如果是字符串字段，则要调用函数转换成sql日期
* @param sDate2
* String：日期同上
* @return String：返回date2-date1的sql表达式
*/
public String sqlDateDiff(String sDate1, String sDate2) {
if (dbType == DB_DB2)
return "days(" + sDate1 + ")-days(" + sDate2 + ")";
else if (dbType == DB_SQL) {
return "DATEDIFF(day," + sDate1 + "," + sDate2 + ")";
} else
return sDate1 + "-" + sDate2;
}