Ios 将一个数据库中的表复制到另一个数据库

我想将表从aDB复制到另一个bDB

所以我制定了一个方法。 我认为Open2数据库和使用insert查询会起作用，但我不知道具体的方法

-(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?


}

---

是这样吗？如何做得更多//源到复制区域。

在sqlite3中，您可以组合附加[1]和创建表。。作为[2]命令：

首先，打开“bDB”数据库，然后执行以下语句：

ATTACH DATABASE "myother.db" AS aDB;

之后，您可以使用CREATE TABLE语法：

CREATE TABLE newTableInDB1 AS SELECT * FROM aDB.oldTableInMyOtherDB;

这将把数据“复制”到新数据库中。 如果要合并数据，还有一个INSERT[3]语句，但需要引用如下字段：

INSERT INTO newtable (field1,field2) 
  SELECT otherfield1,otherfield2 FROM aDB.oldTableInMyOtherDB;

参考资料：

[1]

[2]

---

[3]

经过几个小时的努力，在上面帖子的帮助下，我终于能够创建Objective-C代码来完成这项工作

NSString* dbPath1;
NSString* dbPath2;

dbPath1 = [self getDB1Path]; //This db have the desired table to be copied
dbPath2 = [self getDB2Path]; //This needs to have the desired table 

//open database which contains the desired "table"
if (sqlite3_open(dbPath1.UTF8String, &databasePhase2) == SQLITE_OK)
{
    NSString *attachSQL = [NSString stringWithFormat: @"ATTACH DATABASE \"%@\" AS phase2_db",dbPath2];

    const char *attachSQLChar = [attachSQL UTF8String];
    char* errInfo;
    int result = sqlite3_exec(databasePhase2, attachSQLChar, nil, nil, &errInfo);

    if (SQLITE_OK == result)
    {
        NSLog(@"new db attached");
        NSString *attachSQL = [NSString stringWithFormat: @"CREATE TABLE newTableInDB1 AS SELECT * FROM phase2_db.qmAyahInfo"];

        const char *createSQLChar = [attachSQL UTF8String];
        int result2 = sqlite3_exec(databasePhase2, createSQLChar, nil, nil, &errInfo);
        if (SQLITE_OK == result2)
        {
            NSLog(@"New table created in attached db");
        }
    }
    sqlite3_close(databasePhase2);
}

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+1对于“从aDB.oldTableInMyOtherDB中选择*创建新表格INDB1”的快速表格创建和复制，解释得很好。如果你能用ios objc编写具体的代码，那就太好了。这些命令是纯SQL的，你可以通过调用sqlite3_exec（）来执行它们。别忘了用detach database phase2_db分离数据库，以防你不关闭它。