SQL

#import "ViewController.h"
#import <sqlite3.h>
#import "DataBaseManager.h"
@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    /*
    //获取documents的路径
    NSString *doctmentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
    //创建数据库路径
    NSString *sqlPath = [doctmentsPath stringByAppendingPathComponent:@"student.sqlite"];
    
    //打开数据库,将文件路径转化为char类型的,二阶指针是指针的地址
    //数据库指针sqlite3
#warning 二阶指针 db
    sqlite3 *db = nil;
    NSLog(@"%p",db);
    sqlite3_open(sqlPath.UTF8String, &db);
    NSLog(@"%p",db);
    
    //创建stu表,包含字段s_id,s_name,s_age
    NSString *sqlStr = @"create table if not exists stu (s_id integer primary key,s_name text ,s_age integer)";
    //通过result接受执行结果
    int result = sqlite3_exec(db, sqlStr.UTF8String, NULL, NULL, NULL);
    
    NSLog(@"%@",result == SQLITE_OK ? @"建表成功":@"建表失败");
    NSLog(@"%@",sqlPath);
    
    //插入数据insert into
    NSString *insertSql = @"insert into stu (s_name,s_age) values ('zhangsan',20)";
    int resultInsert = sqlite3_exec(db, insertSql.UTF8String, NULL, NULL, NULL);
    NSLog(@"%@",resultInsert == SQLITE_OK ? @"插入成功":@"插入失败");
    
    //更改数据
    NSString *upSql = @"update stu set s_age = 100 where s_age = 20";
    int resultUpData = sqlite3_exec(db, upSql.UTF8String, NULL, NULL, NULL);
    NSLog(@"%@",resultUpData == SQLITE_OK ? @"更改成功":@"更改失败");
    
    //删除数据
    
    NSString *deleteSql = @"delete from stu";
    int deleteResult = sqlite3_exec(db, deleteSql.UTF8String, NULL, NULL, NULL);
    NSLog(@"%@",deleteResult == SQLITE_OK ? @"删除成功":@"删除失败");
    
    //关闭数据库
    int closeResult = sqlite3_close(db);
    NSLog(@"%@",closeResult == SQLITE_OK ? @"关闭成功":@"关闭失败");
    */
    
    
    DataBaseManager *dbManager = [DataBaseManager shareInstance];
    //使用自定义DataBaseManager,进行数据库操作
    //打开数据库
    [dbManager openDB];
    //创建表
    [dbManager createTable];
    [dbManager insertName:@"张全蛋" Age:20];
    
    NSArray *stuArray =[dbManager selectAll];
    NSLog(@"%@",stuArray);
    NSArray *nameArray = [dbManager selectWithName:@"张全蛋"];
    NSLog(@"张全蛋%@",nameArray);
    [dbManager closeDBm];
    
    
}

#import <Foundation/Foundation.h>

@interface DataBaseManager : NSObject
//单例
+(instancetype)shareInstance;
//打开数据库
-(void)openDB;
//创建表
-(void)createTable;
//插入数据
-(void)insertName:(NSString *)name Age:(NSInteger) age;
//删除数据
-(void)deleteWithName:(NSString *)name;
//更新数据
-(void)updateTable;
//查询数据
-(NSArray *)selectAll;
-(NSArray *)selectWithName:(NSString *)name;
//关闭数据库
-(void)closeDBm;
@end

#import "DataBaseManager.h"
#import <sqlite3.h>
@interface DataBaseManager()
//数据库路径
@property (nonatomic,copy)NSString *sqlPath;

@end

@implementation DataBaseManager
//单例
+(instancetype)shareInstance
{
    static DataBaseManager *manager = nil;
    //两种方式创建单例
    //1.这种方式在工程的整个生命周期只被执行一次,一直到工程关闭被释放
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken,^{
        manager = [[DataBaseManager alloc] init];
    });
//    //2.第二种方法
//    if (manager == nil) {
//        manager = [[DataBaseManager alloc] init];
//    }
    return manager;
}
//重写getter方法
-(NSString *)sqlPath
{
    //if判断避免每次都进行创建
    if (_sqlPath == nil) {
        _sqlPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0] stringByAppendingPathComponent:@"student.sqlite"];
    }
    return _sqlPath;
}
//由于数据库的表指针全局都要用,所以定义为全局变量
static sqlite3 *db = nil;
//打开数据库
-(void)openDB
{
#warning 如果sqlPath写成实例变量的形式则不会走getter方法,
    int result = sqlite3_open(self.sqlPath.UTF8String, &db);
    NSLog(@"%@",result == SQLITE_OK ?@"打开成功":@"打开失败");
}
//创建表
-(void)createTable
{
    //创建表的SQL
#warning 要把类型放前边,约束放后边 如果把主键约束放前边,integer放后边会出错.
    NSString *sqlString = @"create table if not exists stu(s_id integer primary key  autoincrement,s_name text,s_age integer)";
    //执行SQL
    int result = sqlite3_exec(db, sqlString.UTF8String, NULL, NULL, NULL);
    NSLog(@"%@", result == SQLITE_OK ?@"建表成功": @"建表失败");
}
//插入数据
-(void)insertName:(NSString *)name Age:(NSInteger) age;
{
    NSString *sqlString = [NSString stringWithFormat:@"insert into stu (s_name,s_age) values ('%@','%ld')",name,age];
    int result = sqlite3_exec(db, sqlString.UTF8String, NULL, NULL, NULL);
    NSLog(@"%@", result == SQLITE_OK ?@"插入成功": @"插入失败");
}
//删除数据
-(void)deleteWithName:(NSString *)name
{
    NSString *sqlString = [NSString stringWithFormat:@"delete from stu where s_name = '%@'",name];
    int result = sqlite3_exec(db, sqlString.UTF8String, NULL, NULL, NULL);
    NSLog(@"%@", result == SQLITE_OK ?@"删除成功": @"删除失败");
}
//更新数据
-(void)updateTable
{
    NSString *sqlString = @"updata stu set s_age = 10 ";
    int result = sqlite3_exec(db, sqlString.UTF8String, NULL, NULL, NULL);
    NSLog(@"%@", result == SQLITE_OK ?@"更新成功": @"更新失败");
    
}

//查询数据
-(NSArray *)selectAll
{
    NSMutableArray *array =[NSMutableArray new];
    //查询SQL语句
    NSString *sqlString = @"select * from stu";
    //执行查询
    
    //stmt伴随指针
    sqlite3_stmt *stmt = nil;
    //先创建伴随指针,再进行预执行,stmt指向的是step将要执行的语句
    int result = sqlite3_prepare(db, sqlString.UTF8String, -1, &stmt, NULL);
    if (result == SQLITE_OK) {
        //预执行成功,条件循环取出所有数据
        while (sqlite3_step(stmt) == SQLITE_ROW) {
            //第二个参数是指第几列
            NSInteger s_id = sqlite3_column_int(stmt, 0);
            //NSString *name = [NSString stringWithUTF8String:sqlite3_column_text(stmt, 1)];
            //上面的写法报黄,下面的写法没问题
            NSString *name = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 1)];
            
            NSInteger age = sqlite3_column_int(stmt, 2);
            //由于s_id,age不是对象类型的,所以需要用@()这种形式强转
            NSDictionary *studentDic = [NSDictionary dictionaryWithObjectsAndKeys:@(s_id),@"s_id",name,@"s_name",@(age),@"s_age", nil];
            [array addObject:studentDic];
        }
        //释放伴随指针
        sqlite3_finalize(stmt);
        //返回数组
        return array;
    }
    
    return nil;
}
-(NSArray *)selectWithName:(NSString *)name
{
    NSMutableArray *array = [NSMutableArray array];
    //SQL语句
    NSString *sqlString = @"select * from stu where s_name = ?";
    //预执行
    //伴随指针
    sqlite3_stmt *stmt = nil;
    int result = sqlite3_prepare(db, sqlString.UTF8String, -1, &stmt, NULL);
    if (result == SQLITE_OK) {
        //预执行成功,绑定参数 bind
        //sqlite3_column查询获得数据,列数从0开始
        //第二个参数:sqilit3_bind_绑定参数,表示参数所在的列,第三个参数是绑定的参数
        sqlite3_bind_text(stmt, 1, name.UTF8String, -1, NULL);
        while (sqlite3_step(stmt) == SQLITE_ROW) {
            //第二个参数是指第几列
            NSInteger s_id = sqlite3_column_int(stmt, 0);
            //NSString *name = [NSString stringWithUTF8String:sqlite3_column_text(stmt, 1)];
            //上面的写法报黄,下面的写法没问题
            NSString *name = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 1)];
            
            NSInteger age = sqlite3_column_int(stmt, 2);
            //由于s_id,age不是对象类型的,所以需要用@()这种形式强转
            NSDictionary *studentDic = [NSDictionary dictionaryWithObjectsAndKeys:@(s_id),@"s_id",name,@"s_name",@(age),@"s_age", nil];
            [array addObject:studentDic];
        }
        
    }
    //释放伴随指针
    sqlite3_finalize(stmt);
    return array;
}
//关闭数据库
-(void)closeDBm
{
    int result = sqlite3_close(db);
    NSLog(@"%@", result == SQLITE_OK ?@"关闭成功": @"关闭失败");

}
@end