将一个数据库中的表复制到另一个数据库

问题描述

我想将表从aDB复制到另一个bDB。

所以我做了一个方法。
我认为打开2数据库和使用插入查询将工作，但我不知道详细方式。

   - void）copyDatabaseTableSoruceFileName：（NSString *）source CopyFileName：（NSString *）copy 
 {
 sqlite3 * sourceDatabase = NULL; 
 sqlite3 * copyDatabase = NULL; 
 
 NSArray * paths = NSSearchPathForDirectoriesInDomains（NSDocumentDirectory，NSUserDomainMask，YES）; 
 NSString * documentDir = [paths objectAtIndex：0]; 
 
 // source 
 [self copyFileIfNeed：source path：documentDir]; 
 
 NSString * SourceDBPath = [documentDir stringByAppendingPathComponent：source]; 
 if（sqlite3_open（[SourceDBPath UTF8String]，& sourceDatabase）！= SQLITE_OK）
 {
 NSLog（@DB文件打开错误：％@，SourceDBPath）; 
 sourceDatabase = NULL; 
} 
 // copy 
 [self copyFileIfNeed：copy path：documentDir]; 
 
 NSString * CopyDBPath = [documentDir stringByAppendingPathComponent：copy]; 
 if（sqlite3_open（[CopyDBPath UTF8String]，& copyDatabase）！= SQLITE_OK）
 {
 NSLog（@DB文件打开错误：％@，CopyDBPath）; 
 copyDatabase = NULL; 
} 
 
 //来源复制
 
 
 //在这方面如何？ 
 
 
} 
  

是不是？和如何使更多？ // source to copy area。

解决方案

在sqlite3中，可以结合ATTACH [1]和CREATE TABLE ... AS [ 2]命令：

首先，打开bDB数据库，然后执行以下语句：

  ATTACH DATABASEmyother.dbAS aDB;之后，您可以使用CREATE TABLE语法：
 
 $ b 
 
 
  CREATE TABLE newTableInDB1 AS SELECT * FROM aDB.oldTableInMyOtherDB; 
  
这会将数据复制到您的新数据库。 
如果你想合并数据，还有一个INSERT [3]语句，但是你需要引用这样的字段：
  INSERT INTO newtable（field1，field2）
 SELECT otherfield1，otherfield2 FROM aDB.oldTableInMyOtherDB; 
  
参考文献：
 
 
 
 [1] a href =http://www.sqlite.org/lang_attach.html =noreferrer> http://www.sqlite.org/lang_attach.html  
 
 
 
 [2]  
 
I want to copy table from aDB to another bDB. 
So I made a method.I think open 2 database and Using insert query will work but I don't know detail way.
-(void)copyDatabaseTableSoruceFileName:(NSString *)source CopyFileName:(NSString *)copy
{
sqlite3 *sourceDatabase=NULL;
sqlite3 *copyDatabase=NULL;

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);
NSString* documentDir = [paths objectAtIndex:0];

//source
    [self copyFileIfNeed:source path:documentDir];

NSString *SourceDBPath = [documentDir stringByAppendingPathComponent:source];
if( sqlite3_open([SourceDBPath UTF8String],&sourceDatabase)!= SQLITE_OK )
{
    NSLog(@"DB File Open Error :%@", SourceDBPath);
   sourceDatabase = NULL;
}
//copy
[self copyFileIfNeed:copy path:documentDir];

NSString *CopyDBPath = [documentDir stringByAppendingPathComponent:copy];
if( sqlite3_open([CopyDBPath UTF8String],&copyDatabase)!= SQLITE_OK )
{
    NSLog(@"DB File Open Error :%@", CopyDBPath);
    copyDatabase = NULL;
}

//source to copy


 // How in this area?


}
Is it right? and how to make more ? //source to copy area.
 解决方案 
in sqlite3, you can combine the ATTACH[1] and CREATE TABLE .. AS[2] commands:
first, you are opening the "bDB" database, and then execute the following statement:
ATTACH DATABASE "myother.db" AS aDB;
After that, you can use the CREATE TABLE syntax:
CREATE TABLE newTableInDB1 AS SELECT * FROM aDB.oldTableInMyOtherDB;
This will "copy" the data over to your new database.If you want to merge the data, there is also an INSERT[3] statement, but with that you will need to reference your fields like this:
INSERT INTO newtable (field1,field2)
  SELECT otherfield1,otherfield2 FROM aDB.oldTableInMyOtherDB;
References:
[1] http://www.sqlite.org/lang_attach.html
[2] http://www.sqlite.org/lang_createtable.html
[3] http://www.sqlite.org/lang_insert.html
                        
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