致命错误：未捕获的错误：C：\ Xampp \ Htdocs \ Laundry-Master \ _header.Php中的Null上调用成员函数Query（）

Question

我正在使用现有的XAMPP项目，但它给了我这个错误：

  

未定义变量：Pdo在C：\ Xampp \ Htdocs \ Laundry-Master_header.Php中   在线46

但是当我注释掉现有数据库代码时，它运行良好

_header.php

CREATE TABLE [dbo].[Actors] (
    [ActorId] [int] NOT NULL IDENTITY,
    [First_Name] [nvarchar](max),
    [Last_Name] [nvarchar](max),
    [Date_Of_Birth] [datetime] NOT NULL,
    CONSTRAINT [PK_dbo.Actors] PRIMARY KEY ([ActorId])
)
CREATE TABLE [dbo].[Plays] (
    [PlayID] [int] NOT NULL IDENTITY,
    [ActorID] [int] NOT NULL,
    [MovieID] [int] NOT NULL,
    [Pay] [int] NOT NULL,
    CONSTRAINT [PK_dbo.Plays] PRIMARY KEY ([PlayID])
)
CREATE TABLE [dbo].[Movies] (
    [MovieId] [int] NOT NULL IDENTITY,
    [Name] [nvarchar](max),
    [publishDate] [datetime] NOT NULL,
    CONSTRAINT [PK_dbo.Movies] PRIMARY KEY ([MovieId])
)
CREATE INDEX [IX_ActorID] ON [dbo].[Plays]([ActorID])
CREATE INDEX [IX_MovieID] ON [dbo].[Plays]([MovieID])
ALTER TABLE [dbo].[Plays] ADD CONSTRAINT [FK_dbo.Plays_dbo.Actors_ActorID] FOREIGN KEY ([ActorID]) REFERENCES [dbo].[Actors] ([ActorId]) ON DELETE CASCADE
ALTER TABLE [dbo].[Plays] ADD CONSTRAINT [FK_dbo.Plays_dbo.Movies_MovieID] FOREIGN KEY ([MovieID]) REFERENCES [dbo].[Movies] ([MovieId]) ON DELETE CASCADE

index.php代码

Models model = new Models();
var actor = new Actor
{
    Date_Of_Birth = DateTime.Now,
    First_Name = "first name",
    Last_Name = "last name"
}; 
var movie = new Movie
{
    publishDate = DateTime.Now,
    Name = "movieN"
};
model.Movies.Add(movie);
model.SaveChanges();

//adding new relation 
var foundAct = model.Actors.SingleOrDefault(x => x.ActorId == 1);
foundAct.Plays.Add(new Play
{
    ActorID = foundAct.ActorId,
    MovieID = 2// MovieId from Db
}); 
model.SaveChanges();