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我创建了一个在其中使用 sqlite DB 的应用程序。我有一个问题，任何时候运行我的应用程序都会在我的表 sqlite 中添加 NSDictionary。我想检查一次 sqlite，如果表 sqlite 中存在数据，则不要添加，否则添加它。

这是我的代码：

视图控制器.h

#import <UIKit/UIKit.h>
#import "sqlite3.h"

@interface ViewController : UIViewController
{
    sqlite3 * database;
}
@end

视图控制器.m

#import "ViewController.h"
#define DatabaseName @"data.sqlite"
@implementation ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];
    NSArray *idd = [NSArray arrayWithObjects:@"122",@"234",@"453", nil];
    NSArray *name = [NSArray arrayWithObjects:@"janatan",@"fred",@"john", nil];
    NSArray *age = [NSArray arrayWithObjects:@"23",@"35",@"12", nil];
    NSArray *sex = [NSArray arrayWithObjects:@"male",@"male",@"male", nil];
    for (int i = 0; i < [idd count]; i++)
    {
        NSString * a = [idd objectAtIndex:i];
        NSString * b = [name objectAtIndex:i];
        NSString * c = [age objectAtIndex:i];
        NSString * d = [sex objectAtIndex:i];
        NSDictionary * dic = [NSDictionary dictionaryWithObjectsAndKeys:a,@"id",b,@"name",c,@"age",d,@"sex", nil];
        NSString *query = [NSString stringWithFormat:@"insert into table1 (id,name,age,sex) values('%@','%@','%@','%@')",[dic objectForKey:@"id"],[dic objectForKey:@"name"],[dic objectForKey:@"age"],[dic objectForKey:@"sex"]];
        NSLog(@"%@",query);
        [self executeQuery:query];
    }
}
-(NSString *) dataFilePath
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSLog(@"PATH %@",[documentsDirectory stringByAppendingPathComponent:DatabaseName]);
    return [documentsDirectory stringByAppendingPathComponent:DatabaseName];
}

/*==================================================================
 METHOD FOR INSERTING DATA IN DATABASE
 ==================================================================*/
-(void)executeQuery:(NSString *)query
{
    //NSLog(@"QUERY : %@",query);

    sqlite3_stmt *statement;
    if(sqlite3_open([[self dataFilePath] UTF8String], &database) == SQLITE_OK)
    {
        if (sqlite3_prepare_v2(database, [query UTF8String], -1, &statement, NULL) == SQLITE_OK)
        {
            if (sqlite3_step(statement) != SQLITE_DONE)
            {
                sqlite3_finalize(statement);
            }
        }
        else
        {
            NSLog(@"query Statement Not Compiled");
        }

        sqlite3_finalize(statement);
        sqlite3_close(database);
    }
    else
    {
        NSLog(@"Data not Opened");
    }
}
@end

我还想在NSDictionary更改例如数组时是字典增加值更新 sqlite 完成。

请解释一下。

4

1 回答 1

8

使用此方法：

/*==================================================================
    METHOD FOR CHECKING WHETHER RECORD EXISTS OR NOT IN DATABASE
 ==================================================================*/

-(BOOL)recordExistOrNot:(NSString *)query{
    BOOL recordExist=NO;
    if(sqlite3_open([[self dataFilePath] UTF8String], &database) == SQLITE_OK)
    {
        sqlite3_stmt *statement;
        if (sqlite3_prepare_v2(database, [query UTF8String], -1, &statement, nil)==SQLITE_OK)
        {
            if (sqlite3_step(statement)==SQLITE_ROW)
            {
                recordExist=YES;
            }
            else
            {
                //////NSLog(@"%s,",sqlite3_errmsg(database));
            }
            sqlite3_finalize(statement);
            sqlite3_close(database);
        }
    }
    return recordExist;
}

如果记录存在则返回 YES 否则不存在。前任 ：

          NSString *query  = [NSString stringWithFormat:@"select * from yourtable where column_name = 'column_name'"];

        NSLog(@"query : %@",query);
        BOOL recordExist = [self recordExistOrNot:query];

        if (!recordExist) {
            // Insert your data
        }

希望它可以帮助你。

于 2013-05-01T10:26:04.303 回答