在这里,我想使用两个数据库执行查询,并将数据从数据库1的表复制到另一个数据库2。 在这里,我可以打开一个数据库,但在打开其他数据库时遇到问题。提前感谢大家。
CurrentStatus *status = [CurrentStatus sharedCurrentStatus];
sqlite3 *database;
sqlite3 *database1;
sqlite3_stmt *statement;
sqlite3_stmt *statement1;
NSString *dbPath = [status.applicationDocumentDirectory stringByAppendingPathComponent:@"database.sqlite"];
NSString *dbPath1 = [status.applicationDocumentDirectory stringByAppendingPathComponent:@"database1.sqlite"];
if ((sqlite3_open_v2([dbPath UTF8String], &database, SQLITE_OPEN_READWRITE , NULL) == SQLITE_OK) && (sqlite3_open_v2([dbPath1 UTF8String], &database1, SQLITE_OPEN_READWRITE , NULL) == SQLITE_OK)) {
NSString *sqlStr = [[NSString alloc] initWithFormat:@"select * from Login" ];
NSString *sql = [[NSString alloc] initWithString:sqlStr];
if ((sqlite3_prepare_v2(database, [sql UTF8String], -1, &statement, NULL) == SQLITE_OK)) {
NSLog(@"DB prepare_v2 Opening successfully");
if (sqlite3_step(statement) == SQLITE_ROW) {
}
else
{
}
sqlite3_finalize(statement);
NSLog(@"DB Opening successfully");
sqlite3_close(database);
}else
{
NSLog(@"else DB Opening successfully");
}
sqlite3_close(database);
}
尝试类似的事情来完成你的任务..
首先,打开"DB1"数据库,然后执行以下语句:
ATTACH DATABASE "2ndDB.db" AS 2ndDB;
之后,您可以使用 CREATE TABLE 语法:
CREATE TABLE newTableInDB1 AS SELECT * FROM 2ndDB.oldTableInMyOtherDB;
这会将数据"复制"到新数据库
从数据库 1 复制您想要的数据 在 NSMutableDictionary 中添加每一行,然后将其添加到 NSMutableArray。关闭并重置语句,然后打开数据库2,从 NSMutableArray 复制数据,该数组充当您的数据库。.
我希望它能为你工作..
数据库,然后将表从一个数据库复制到另一个数据库。你需要做这样的事情:
NSString *attachSQL = [NSString stringWithFormat: @"ATTACH DATABASE '%s' AS %@", sourceDBPath,dbAlias];
if (sqlite3_exec(db, [attachSQL UTF8String], NULL, NULL, &errorMessage) != SQLITE_OK)
{
NSString *errorStr = [NSString stringWithFormat:@"The database could not be attached: %@",[NSString stringWithCString:errorMessage encoding:NSUTF8StringEncoding]];
return errorStr;
}
之后你需要复制表,比如:
NSString *queryString=[NSString stringWithFormat:@"CREATE TABLE %@ AS SELECT * FROM %@.%@;",newTableName,dbAlias,origTableName];
您完成了,您拥有数据库的新副本。