iOS中sqlite的基本使用

// 初始化数据库
- (void)setupDb
{
    // 开发数据库（连接数据库）
    NSString *filename = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"shops.sqlite"];

    //    filename.UTF8String  直接把OC转成C

    int status = sqlite3_open(filename.UTF8String, &_db);

    if (status == SQLITE_OK) {  // 打开数据库成功
        NSLog(@"打开数据库成功");
        // 创表
        const char *sql = "CREATE TABLE IF NOT EXISTS t_shop (id integer PRIMARY KEY, name text NOT NULL, price real)";
        char *errmsg = NULL;
        sqlite3_exec(self.db, sql, NULL, NULL, &errmsg);
        if (errmsg) {
            NSLog(@"创建数据库失败");
        } else {
            NSLog(@"创建数据库成功");
        }

    } else {  // 打开数据库失败
        NSLog(@"打开数据库失败");

    }
}

// 查询数据- (void)setupData{    const char *sql = "SELECT name,price FROM t_shop;";    // 用来取查询结果的    sqlite3_stmt *stmt = NULL;    // 准备    int status = sqlite3_prepare_v2(self.db, sql, -1, &stmt, NULL);    if (status == SQLITE_OK) {  // 准备成功        while (sqlite3_step(stmt) == SQLITE_ROW) {  // 成功取出一条数据            const char *name = (const char *)sqlite3_column_text(stmt, 0);  // 列（字段）            const char *price = (const char *)sqlite3_column_text(stmt, 1);                        JYShop *shop = [[JYShop alloc] init];            shop.name = [NSString stringWithUTF8String:name];            shop.price = [NSString stringWithUTF8String:price];            [self.shops addObject:shop];        }    }}

- (IBAction)insert {
//    const char *sql = "INSERT INTO t_shop(name, price) VALUES('','');";

    NSString *sql = [NSString stringWithFormat:@"INSERT INTO t_shop(name, price) VALUES('%@',%f);",self.nameField.text, self.priceField.text.doubleValue];

    sqlite3_exec(self.db, sql.UTF8String, NULL, NULL, NULL);

    // 刷新表格
    JYShop *shop = [[JYShop alloc] init];
    shop.name = self.nameField.text;
    shop.price = self.priceField.text;
    [self.shops addObject:shop];
    [self.tableView reloadData];
}