SQLite的基本封装

/** 获取单例对象 */
+ (instancetype)shareManage;

static SQLManager *_instance;
+ (instancetype)shareManage
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _instance = [[SQLManager alloc] init];
    });
    return _instance;
}

+ (void)initialize
{
    // 拼接数据库地址
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];
    NSString *sqlFile = [path stringByAppendingPathComponent:@"student.sqlite"];
    // 打开数据
    int result = sqlite3_open(sqlFile.UTF8String, &_db);// [self db]
    // 判断是否打开成功
    if (result == SQLITE_OK) {
        NSLog(@"打开成功");
        // 3.1创建表
        NSString *sql = @"CREATE TABLE IF NOT EXISTS t_student(id INTEGER PRIMARY KEY AUTOINCREMENT , name TEXT, age INTEGER, score REAL);";
        result = sqlite3_exec(_db, sql.UTF8String, NULL, NULL, NULL);
    }
}

/** 插入学生数据 */
- (BOOL)insertStudent:(HMStudent *)student;

@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) int age;
@property (nonatomic, assign) double score;
@property (nonatomic, assign) int ID;

- (BOOL)insertStudent:(HMStudent *)student
{
    NSString *sql = [NSString stringWithFormat: @"INSERT INTO t_student(age, score, name) VALUES (%d, %f, '%@');", student.age, student.score, student.name];
    int result =  sqlite3_exec(_db, sql.UTF8String, NULL, NULL, NULL);
    if (result == SQLITE_OK) {
        return YES;
    }
    return NO;
}

    
Student *stu = [[Student alloc] init];
    stu.name = @"lnj";
    stu.age = 30;
    stu.score = 100.0;
    if ([[SQLManager shareManage]insertStudent:stu]) {
        NSLog(@"插入成功");
    }

- (NSArray *)query;

NSString *sql = @"SELECT * FROM t_student;";
    sqlite3_stmt *stemt = NULL;
    sqlite3_prepare_v2(_db, sql.UTF8String, -1, &stemt, NULL);
    // 判断有没有查询结果
    NSMutableArray *arrM = [NSMutableArray array];
    while (sqlite3_step(stemt) == SQLITE_ROW) {
        // 取出查询到得结果
        const unsigned char *name = sqlite3_column_text(stemt, 1);
        int age = sqlite3_column_int(stemt, 2);
        double score = sqlite3_column_double(stemt, 3);
        HMStudent *stu = [[HMStudent alloc] init];
        stu.name = [NSString stringWithUTF8String:name];
        stu.age = age;
        stu.score = score;
        [arrM addObject:stu];
    }
    return arrM;

NSArray *arr = [[SQLManager shareManage] query];
    for (Student *stu in arr) {
        NSLog(@"%@", stu);
    }