数据库中的模糊查询

今日的勤奋，只是为了明日拥有可以懒惰的权利！

+ (NSArray *)studentsWithCondition:(NSString *)condition
{
    // 0.定义数组
    NSMutableArray *students = nil;
    
    // 1.定义sql语句
    const char *sql = "select id, name, age from t_student where name like ?;";
    
    // 2.定义一个stmt存放结果集
    sqlite3_stmt *stmt = NULL;
    
    // 3.检测SQL语句的合法性
    int result = sqlite3_prepare_v2(_db, sql, -1, &stmt, NULL);
    if (result == SQLITE_OK) {
        NSLog(@"查询语句是合法的");
        students = [NSMutableArray array];
        
        // 填补占位符的内容
        NSString *newCondition = [NSString stringWithFormat:@"%%%@%%", condition];
//        NSLog(@"%@", newCondition);
        sqlite3_bind_text(stmt, 1, newCondition.UTF8String, -1, NULL);
        
        // 4.执行SQL语句，从结果集中取出数据
        while (sqlite3_step(stmt) == SQLITE_ROW) { // 真的查询到一行数据
            // 获得这行对应的数据
            
            IWStudent *student = [[IWStudent alloc] init];
            
            // 获得第0列的id
            student.ID = sqlite3_column_int(stmt, 0);
            
            // 获得第1列的name
            const unsigned char *sname = sqlite3_column_text(stmt, 1);
            student.name = [NSString stringWithUTF8String:(const char *)sname];
            
            // 获得第2列的age
            student.age = sqlite3_column_int(stmt, 2);
            
            // 添加到数组
            [students addObject:student];
        }
    } else {
        NSLog(@"查询语句非合法");
    }
    
    return students;
}