文章內容

MySQL轉數據到Oracle

發布時間: 2012/8/23 16:43:24

一、首先從網絡上找到一些資料如下：
1．自動增長的數據類型處理

MYSQL有自動增長的數據類型，插入記錄時不用操作此字段，會自動獲得數據值。Oracle沒有自動增長的數據類型，需要建立一個自動增長的序列號，插入記錄時要把序列號的下一個值賦于此字段。

CREATE SEQUENCE 序列號的名稱 (最好是表名+序列號標記) INCREMENT BY 1 START WITH 1 MAXVALUE 99999 CYCLE NOCACHE;
-

INSERT 語句插入這個字段值為: 序列號的名稱.NEXTVAL

2. 單引號的處理

MYSQL里可以用雙引號包起字符串，Oracle里只可以用單引號包起字符串。在插入和修改字符串前必須做單引號的替換：把所有出現的一個單引號替換成兩個單引號。當然你如果使用 Convert Mysql to Oracle 工具就不用考慮這個問題

3．長字符串的處理

在Oracle中，INSERT和UPDATE時最大可操作的字符串長度小于等于4000個單字節, 如果要插入更長的字符串, 請考慮字段用CLOB類型，方法借用ORACLE里自帶的DBMS_LOB程序包。插入修改記錄前一定要做進行非空和長度判斷，不能為空的字段值和超出長度字段值都應該提出警告,返回上次操作。

4. 翻頁的SQL語句的處理

MYSQL處理翻頁的SQL語句比較簡單，用LIMIT 開始位置, 記錄個數。Oracle處理翻頁的SQL語句就比較繁瑣了。每個結果集只有一個ROWNUM字段標明它的位置, 并且只能用ROWNUM<100, 不能用ROWNUM>80。

以下是經過分析后較好的兩種Oracle翻頁SQL語句( ID是唯一關鍵字的字段名 )：

語句一：SELECT ID, [FIELD_NAME,...] FROM TABLE_NAME WHERE ID IN ( SELECT ID FROM (SELECT ROWNUM AS NUMROW, ID FROM TABLE_NAME WHERE 條件1 ORDER BY 條件2) WHERE NUMROW > 80 AND NUMROW < 100 ) ORDER BY 條件3;

語句二：SELECT * FROM (( SELECT ROWNUM AS NUMROW, c.* from (select [FIELD_NAME,...] FROM TABLE_NAME WHERE 條件1 ORDER BY 條件2) c) WHERE NUMROW > 80 AND NUMROW < 100 ) ORDER BY 條件3;

5. 日期字段的處理

MYSQL日期字段分DATE和TIME兩種，Oracle日期字段只有DATE，包含年月日時分秒信息，用當前數據庫的系統時間為SYSDATE, 精確到秒。

日期字段的數學運算公式有很大的不同。MYSQL找到離當前時間7天用 DATE_FIELD_NAME > SUBDATE（NOW（），INTERVAL 7 DAY）Oracle找到離當前時間7天用 DATE_FIELD_NAME >SYSDATE - 7;

6. 字符串的模糊比較

MYSQL里用字段名 like '%字符串%',Oracle里也可以用字段名 like '%字符串%' 但這種方法不能使用索引, 速度不快，用字符串比較函數 instr(字段名,'字符串')>0 會得到更精確的查找結果。

7. 空字符的處理

MYSQL的非空字段也有空的內容，Oracle里定義了非空字段就不容許有空的內容。按MYSQL的NOT NULL來定義ORACLE表結構, 導數據的時候會產生錯誤。因此導數據時要對空字符進行判斷，如果為NULL或空字符，需要把它改成一個空格的字符串。

以上內容我作為參考。

二．工具的使用

網上好多朋友介紹使用Convert Mysql to Oracle這個工具，當然能用工具解決的問題我們就用工具，關鍵是看工具能不能解決問題。通過工具會出現好多問題，最終還是要自己寫程式解決。后來發現工具導數據還是可以的，數據表的創建和修改只有自己寫程式解決了。但是導數據也有問題,如下:

導入數據遇到的問題

1、text到blob的時候，這個是影響很大的，不是我們希望看到的，就不要做多說明。

2、在Mysql中如果是Varchar或char中字符大小為2，意味著它可以輸入“12、中國、1中”等2個長度的數據，而在Oracle中是針對字節的，它只允許輸入英文字符2個或一個中文漢字，所以這變在導數據的時候要注意欄位的大小。

3、導入的過程中字符集必須要設置正確，否則會出現亂碼的數據。

4、index是不可以導進來的，要注意table是否有Index；是否允許NULL值也要注意。

5、Mysql中id自動增長的table要做處理，在Oracle中設置相關的sequence和trigger。

6、comment在Oracle中是關鍵字，不能當做列來處理。

7、當數據量大的時候做特別處理。

三．自己寫程式解決問題

//獲得所有table的名字

SELECT
`TABLES`.`TABLE_SCHEMA`, `TABLES`.`TABLE_NAME`
FROM
`information_schema`.`TABLES`
WHERE
`TABLES`.`TABLE_TYPE` = 'base table'
and `TABLES`.`TABLE_SCHEMA` ='netoffice';

//獲得某table所有列的信息

SELECT * FROM
`information_schema`.`COLUMNS`

where `TABLE_SCHEMA`='netoffice'

and `TABLE_NAME`='drmcertification' order by `ORDINAL_POSITION`;

//java程式:

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Vector;

public class TestMysql {
public static Connection conn;
public static Statement statement;
public Hashtable<String, Vector<Vector<String>>> hashtable = new Hashtable<String, Vector<Vector<String>>>();
public static final String filepathCreateTable = "D://CreateTable.txt";
public static final String filepathCreateSequence = "D://CreateSequence.txt";
public static final String filepathCreateTrigger = "D://CreateTrigger.txt";
public static final String filepathCreatePrimarykey = "D://CreatePrimarykey.txt";
public static final String filepathCreateIndex = "D://CreateIndex.txt";

//只要修改主機名，數據庫名字和user、password
public static final String DBdriver = "com.mysql.jdbc.Driver";
public static final String DBURL = "jdbc:mysql://主機地址:3306/數據庫名字?user=roots&password=1234";
public static final String DBSCHEMA = "數據庫名字"; //

public static void main(String[] args) {
new TestMysql();
}

public TestMysql() {

//刪除文件
deleteFile();

if (!connectionMethod()) {
System.out.println("鏈接錯誤");
return;
}

Vector<String> table = queryAllTable(DBSCHEMA);
if (table.size() == 0) {
System.out.println("沒有找到表");
return;
}

for (int i = 0; i < table.size(); i++) { //得到數據
hashtable.put(table.get(i), handle_table(table.get(i)));
}

// hashtable.put(table.get(0).toString(),handle_table(table.get(0)));
System.out.println("操作正在進行中,請耐心等待......");
generatorString(hashtable); //產生字符串

close();//關閉連接
System.out.println("finish");
}

public void generatorString(Hashtable hashtable) {
Iterator iter = hashtable.keySet().iterator();
while (iter.hasNext()) {
   String tablescript = ""; // 創表語句
   String tablesequence = ""; // 建立sequence
   String tabletrigger = ""; // 建立trigger
   String tableprimarykey = "";// 建立主鍵
   String tableindex = "";// 建立索引
   String primarkeyColumn = "";
   String indexColumn = "";

int primarykey = 0;
int index = 0;

   String tablename = (String) iter.next();
   Vector valall = (Vector) hashtable.get(tablename);
   tablescript = "create table " + tablename + "(";
   for (int i = 0; i < valall.size(); i++) {
    Vector<String> val = (Vector) valall.get(i);
    String column_name = val.get(0).toString();// 列名
    String is_nullable = val.get(1).toString();// 是否為空，如果不允許NO,允許為YES
    String data_type = val.get(2).toString();// int,varchar,text,timestamp,date
    String character_maximun_length = val.get(3).toString();// 長度大小
    String column_key = val.get(4).toString();// 是否主鍵是的話為PRI
               // MUL(index)
               // 有兩個PRI說明是複合index
    String extra = val.get(5).toString(); // 是否自動增長列是的話
              // auto_increment
    String column_default = val.get(6).toString();// 是否有默認值

    if (data_type.equals("varchar") || data_type.equals("char")) { // 驗證是否有中文字符
     if (judge_china(tablename, column_name)) {
      character_maximun_length = Integer
        .parseInt(character_maximun_length)
        * 3 + "";
     }
    }

    tablescript = tablescript + column_name + " ";
    if (data_type.equals("int")) {
     tablescript = tablescript + "NUMBER" + " ";
    } else if (data_type.equals("mediumint")) {
     tablescript = tablescript + "NUMBER" + " ";
    } else if (data_type.equals("char")) {
     tablescript = tablescript + "varchar2("
       + character_maximun_length + ")" + " ";
    } else if (data_type.equals("varchar")) {
     tablescript = tablescript + "varchar2("
       + character_maximun_length + ")" + " ";
    } else if (data_type.equals("text")) {
     tablescript = tablescript + "varchar2(4000) ";
    } else if (data_type.equals("timestamp")) {
     tablescript = tablescript + "date" + " ";
    } else if (data_type.equals("date")) {
     tablescript = tablescript + "date" + " ";
    } else if (data_type.equals("float")) {
     tablescript = tablescript + "NUMBER" + " ";
    } else if (data_type.equals("longtext")) {
     tablescript = tablescript + "varchar2(4000) ";
    } else if (data_type.equals("smallint")) {
     tablescript = tablescript + "NUMBER" + " ";
    } else if (data_type.equals("double")) {
     tablescript = tablescript + "NUMBER" + " ";
    } else if (data_type.equals("datetime")) {
     tablescript = tablescript + "date" + " ";
    }

    if (column_default.length() > 0) { // 是否有默認值
     if (column_default.equals("CURRENT_TIMESTAMP")) {
      tablescript = tablescript + "default sysdate" + " ";
     } else {
      tablescript = tablescript + "default " + column_default
        + " ";
     }
    }

    if (is_nullable.equals("NO")) { // 是否為空值
     tablescript = tablescript + "not null,";
    } else {
     tablescript = tablescript + ",";
    }

    if (extra.equals("auto_increment")) { // 是否自動增長列
     int maxid = get_maxId(tablename, column_name);
     tablesequence = "create sequence sq_" + tablename + " "
       + "minvalue " + maxid + " "
       + "maxvalue 9999999999999999 " + "increment by 1 "
       + "start with " + maxid + " " + "cache 20;";
     tabletrigger = "EXECUTE IMMEDIATE 'create trigger tr_"
       + tablename + " " + "before " + "insert on "
       + tablename + " for each row " + "begin "
       + "select sq_" + tablename + ".nextval into:new."
       + column_name + " from dual; " + "end;';";
    }

    if (column_key.length() > 0) {
     if (column_key.equals("PRI")) {
      primarykey++;
      primarkeyColumn = primarkeyColumn + column_name + ",";
     } else if (column_key.equals("MUL")) {
      index++;
      indexColumn = indexColumn + column_name + ",";
     }
    }

}

   if (primarykey == 1) {
    primarkeyColumn = primarkeyColumn.substring(0, primarkeyColumn
      .length() - 1);
    String key = "pr_" + tablename + "_" + primarkeyColumn;
    if (key.length() > 30) {
     key = "pr_" + primarkeyColumn;
    }
    tableprimarykey = "alter table " + tablename
      + " add constraint " + key + " primary key ("
      + primarkeyColumn + ");";
   } else {
    primarkeyColumn = primarkeyColumn.substring(0, primarkeyColumn
      .length() - 1);
    String indextemp = tablename + "_index";
    if (indextemp.length() > 30)
     indextemp = primarkeyColumn.replace(',', '_') + "_index";
    tableindex = "create index " + indextemp + " on " + tablename
      + " (" + primarkeyColumn + ");";
   }

   if (index > 0) {
    indexColumn = indexColumn
      .substring(0, indexColumn.length() - 1);
    String indextemp = tablename + "_index";
    if (indextemp.length() > 30)
     indextemp = indexColumn.replace(',', '_') + "_index";
    tableindex = "create index " + indextemp + " on " + tablename
      + " (" + indexColumn + ");";
   }

tablescript = tablescript.substring(0, tablescript.length() - 1);
tablescript = tablescript + ");";

   if (tablescript.length() > 0)
    write(filepathCreateTable, tablescript);
   if (tablesequence.length() > 0)
    write(filepathCreateSequence, tablesequence);
   if (tabletrigger.length() > 0)
    write(filepathCreateTrigger, tabletrigger);
   if (tableprimarykey.length() > 0)
    write(filepathCreatePrimarykey, tableprimarykey);
   if (tableindex.length() > 0)
    write(filepathCreateIndex, tableindex);

}

public void close() {
try {
   statement.close();
   conn.close();
} catch (SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
}
}

public Vector<Vector<String>> handle_table(String tablename) {
Vector<Vector<String>> arg = new Vector<Vector<String>>();
try {
   String queryDetail = "SELECT * "
     + "FROM `information_schema`.`COLUMNS` "
     + "where `TABLE_SCHEMA`='" + DBSCHEMA + "' "
     + "and `TABLE_NAME`='" + tablename + "' "
     + "order by `ORDINAL_POSITION`";
   // System.out.println("sql= "+queryDetail);
   ResultSet rst = statement.executeQuery(queryDetail);

   while (rst.next()) {
    Vector<String> vec = new Vector<String>();
    String column_name = NulltoSpace(rst.getString("COLUMN_NAME"));// 列名
    String is_nullable = NulltoSpace(rst.getString("IS_NULLABLE"));// 是否為空，如果不允許NO,允許為YES
    String data_type = NulltoSpace(rst.getString("DATA_TYPE"));// int,varchar,text,timestamp,date
    String character_maximun_length = NulltoSpace(rst
      .getString("CHARACTER_MAXIMUM_LENGTH"));// 長度大小
    String column_key = NulltoSpace(rst.getString("COLUMN_KEY"));// 是否主鍵
                    // 是的話為PRI
                    // MUL(index)
                    // 有兩個PRI說明是複合index
    String extra = NulltoSpace(rst.getString("EXTRA")); // 是否自動增長列
                 // 是的話
                 // auto_increment
    String column_default = NulltoSpace(rst
      .getString("COLUMN_DEFAULT"));// 是否有默認值
    vec.add(column_name);
    vec.add(is_nullable);
    vec.add(data_type);
    vec.add(character_maximun_length);
    vec.add(column_key);
    vec.add(extra);
    vec.add(column_default);
    arg.add(vec);
   }
   rst.close();
} catch (SQLException e) {
   e.printStackTrace();
}

return arg;
}

public boolean judge_china(String tablename, String columnname) {
try {
   String querysql = "select count(1) row from " + tablename
     + " where length(" + columnname + ")!=char_length("
     + columnname + ")";
   // System.out.println("sql= "+querysql);
   ResultSet rst = statement.executeQuery(querysql);
   if (rst.next()) {
    if (NulltoSpace(rst.getString("row")).equals("0")) {
     return false;
    } else {
     return true;
    }
   }
    rst.close();
} catch (SQLException e) {
   // TODO Auto-generated catch block
}
return true;
}

public int get_maxId(String tablename, String columnname) {
String maxValue = "0";
try {
   String querysql = "select max(" + columnname + ") maxid from "
     + tablename;
   // System.out.println("sql= "+querysql);
   ResultSet rst = statement.executeQuery(querysql);
   if (rst.next()) {
    maxValue = NulltoSpace(rst.getString("maxid"));
   }
    rst.close();
} catch (SQLException e) {
}
return Integer.parseInt(maxValue + 1);
}

public Vector<String> queryAllTable(String table_schema) {
Vector<String> tableName = new Vector<String>();
try {
   String queryTable = "SELECT `TABLES`.`TABLE_NAME` "
     + "FROM `information_schema`.`TABLES` "
     + "WHERE `TABLES`.`TABLE_TYPE` = 'base table' "
     + "and `TABLES`.`TABLE_SCHEMA` ='" + table_schema + "'";
   // System.out.println("sql= "+queryTable);
   ResultSet rst = statement.executeQuery(queryTable);
   while (rst.next()) {
    tableName.add(NulltoSpace(rst.getString("TABLE_NAME")));
   }
} catch (SQLException e) {
   // TODO Auto-generated catch block
}
return tableName;
}

public boolean connectionMethod() {
try {
   Class.forName(DBdriver).newInstance();
   conn = DriverManager.getConnection(DBURL);
   statement = conn.createStatement();
   return true;
} catch (Exception e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
   return false;
}
}

public static String NulltoSpace(Object o) {
if (o == null)
   return "";
else if (o.equals("null")) {
   return "";
} else {
   return o.toString().trim();
}
}

public static void deleteFile(){
File f;
f= new File(filepathCreateTable);
if(f.exists()) f.delete();
f= new File(filepathCreatePrimarykey);
if(f.exists()) f.delete();
f= new File(filepathCreateSequence);
if(f.exists()) f.delete();
f= new File(filepathCreateTrigger);
if(f.exists()) f.delete();
f= new File(filepathCreateIndex);
if(f.exists()) f.delete();
}

public static void write(String path, String content) {
String s = new String();
String s1 = new String();
try {
   File f = new File(path);
   if (f.exists()) {
   } else {
       f.createNewFile();
   }
   BufferedReader input = new BufferedReader(new FileReader(f));

   while ((s = input.readLine()) != null) {
    s1 += s + "\r\n";
   }
   input.close();
   s1 += content;

   BufferedWriter output = new BufferedWriter(new FileWriter(f));
   output.write(s1);
   output.close();
} catch (Exception e) {
   e.printStackTrace();
}
}

}

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