如何在数据库操作中插入更新删除并将数据库保存在文档目录中[关闭]

Posted 2023-03-12

【中文标题】如何在数据库操作中插入更新删除并将数据库保存在文档目录中[关闭]

【英文标题】：How to insert update delete in database operation and also save database in document directory [closed]

【发布时间】：2013-09-23 06:39:15

【问题描述】：

我需要通过查询获取数据库并插入更新删除，以便任何类都可用于简单操作

 +(void)createEditableCopyOfDatabaseIfNeeded 
    BOOL success;
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDirectory = [paths objectAtIndex:0];
    NSString *writableDBPath = [documentDirectory stringByAppendingPathComponent:@"YOUR DB NAME"];
    success = [fileManager fileExistsAtPath:writableDBPath];
    if (success) 
        return;
    
    NSString *defualtDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"YOUR DB NAME"];
    success = [fileManager copyItemAtPath:defualtDBPath toPath:writableDBPath error:&error];

    if (!success) 
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:@"Database Error!!" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
        [alert release];
    

我需要通过查询完成操作...

【问题讨论】：

你有没有试过在谷歌上找到这个。看看Goodle search和一个reference link

您解决了或需要帮助吗？？

【参考方案1】：

在下面给出的创建文件 把这个写在database.h文件中

    #import <Foundation/Foundation.h>
    #import <sqlite3.h>

    @interface Database : NSObject 
   
   +(NSString* )getDatabasePath;
   +(NSMutableArray *)executeQuery:(NSString*)str;
   +(NSString*)encodedString:(const unsigned char *)ch;
   +(BOOL)executeScalarQuery:(NSString*)str;
   @end

这将在 database.m 文件中

   #import "Database.h"
 #import <sqlite3.h>


  @implementation Database

  +(NSString* )getDatabasePath
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"YOURDBNAME"];
return writableDBPath;

    

  +(NSMutableArray *)executeQuery:(NSString*)str
  
sqlite3_stmt *statement= nil;
sqlite3 *database;
NSString *strPath = [self getDatabasePath];
NSMutableArray *allDataArray = [[NSMutableArray alloc] init];
if (sqlite3_open([strPath UTF8String],&database) == SQLITE_OK) 

    if (sqlite3_prepare_v2(database, [str UTF8String], -1, &statement, NULL) == SQLITE_OK) 
    
        while (sqlite3_step(statement) == SQLITE_ROW) 
        
            NSInteger i = 0;
            NSInteger iColumnCount = sqlite3_column_count(statement);
            NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
            while (i< iColumnCount) 
                NSString *str = [self encodedString:(const unsigned char*)sqlite3_column_text(statement, i)];
                NSString *strFieldName = [self encodedString:(const unsigned char*)sqlite3_column_name(statement, i)];
                [dict setObject:str forKey:strFieldName];
                i++;
            

            [allDataArray addObject:dict];
            [dict release];
        
    
    else 
         NSAssert1(0, @"Error: failed to prepare statement with message '%s'.", sqlite3_errmsg(database));
    

    sqlite3_finalize(statement);
 
sqlite3_close(database);
return allDataArray;
  
  +(BOOL)executeScalarQuery:(NSString*)str

sqlite3_stmt *statement= nil;
sqlite3 *database;
BOOL fRet = NO;
NSString *strPath = [self getDatabasePath];
if (sqlite3_open([strPath UTF8String],&database) == SQLITE_OK) 
    if (sqlite3_prepare_v2(database, [str UTF8String], -1, &statement, NULL) == SQLITE_OK) 
        if (sqlite3_step(statement) == SQLITE_DONE)
            fRet =YES;
    

    sqlite3_finalize(statement);
 
sqlite3_close(database);
return fRet;
   


   +(NSString*)encodedString:(const unsigned char *)ch
    
NSString *retStr;
if(ch == nil)
    retStr = @"";
else
    retStr = [NSString stringWithCString:(char*)ch encoding:NSUTF8StringEncoding];
return retStr;
   

   @end