MySQL转数据到Oracle

MYSQL有自动增长的数据类型，插入记录时不用操作此字段，会自动获得数据值。ORACLE没有自动增长的数据类型，需要建立一个自动增长

一、首先從網絡上找到一些資料如下：

1． 自动增长的数据类型处理

MYSQL有自动增长的数据类型，插入记录时不用操作此字段，会自动获得数据值。Oracle没有自动增长的数据类型，需要建立一个自动增长的序列号，插入记录时要把序列号的下一个值赋于此字段。

CREATE SEQUENCE 序列号的名称 (最好是表名+序列号标记) INCREMENT BY 1 START WITH 1 MAXVALUE 99999 CYCLE NOCACHE;

INSERT 语句插入这个字段值为: 序列号的名称.NEXTVAL

2. 单引号的处理

MYSQL里可以用双引号包起字符串，ORACLE里只可以用单引号包起字符串。在插入和修改字符串前必须做单引号的替换：把所有出现的一个单引号替换成两个单引号。当然你如果使用 Convert Mysql to Oracle 工具就不用考虑这个问题

3．长字符串的处理

在ORACLE中，INSERT和UPDATE时最大可操作的字符串长度小于等于4000个单字节, 如果要插入更长的字符串, 请考虑字段用CLOB类型，方法借用ORACLE里自带的DBMS_LOB程序包。插入修改记录前一定要做进行非空和长度判断，不能为空的字段值和超出长度字段值都应该提出警告,返回上次操作。

4. 翻页的SQL语句的处理

MYSQL处理翻页的SQL语句比较简单，用LIMIT 开始位置, 记录个数。ORACLE处理翻页的SQL语句就比较繁琐了。每个结果集只有一个ROWNUM字段标明它的位置, 并且只能用ROWNUM<100, 不能用ROWNUM>80。

以下是经过分析后较好的两种ORACLE翻页SQL语句( ID是唯一关键字的字段名 )：

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

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

5. 日期字段的处理

MYSQL日期字段分DATE和TIME两种，ORACLE日期字段只有DATE，包含年月日时分秒信息，用当前数据库的系统时间为SYSDATE, 精确到秒。

日期字段的数学运算公式有很大的不同。MYSQL找到离当前时间7天用 DATE_FIELD_NAME > SUBDATE（NOW（），INTERVAL 7 DAY）ORACLE找到离当前时间7天用 DATE_FIELD_NAME >SYSDATE - 7;

6. 字符串的模糊比较

MYSQL里用 字段名 like '%字符串%',ORACLE里也可以用 字段名 like '%字符串%' 但这种方法不能使用索引, 速度不快，用字符串比较函数 instr(字段名,'字符串')>0 会得到更精确的查找结果。

7. 空字符的处理

MYSQL的非空字段也有空的内容，ORACLE里定义了非空字段就不容许有空的内容。按MYSQL的NOT NULL来定义ORACLE表结构, 导数据的时候会产生错误。因此导数据时要对空字符进行判断，，如果为NULL或空字符，需要把它改成一个空格的字符串。

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。通过工具会出现好多问题，最终还是要自己写程式解决。后来发现工具导数据还是可以的，数据表的创建和修改只有自己写程式解决了。但是导数据也有问题,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．自己写程式解决问题

//获得所有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';

//获得某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>> hashtable = new Hashtable>>();
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 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 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> handle_table(String tablename) {
Vector> arg = new Vector>();
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 vec = new Vector();
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 queryAllTable(String table_schema) {
Vector tableName = new Vector();
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();
}
}

}