更新SQL語句中的錯誤

Question

我試圖制定一個UPDATE SQL語句具有左外部聯接。當a.count小於subjects._max_enrollment_no或a.count爲NULL時，應該提交UPDATE。當我嘗試提交查詢時，會出現如下所示的錯誤。

UPDATE [e-request] 
SET ereq_status = N'A' 
FROM [e-request] 
     LEFT OUTER JOIN (SELECT Count(em_st_id) AS count, 
           em_sj_id 
         FROM enrollment 
         WHERE (em_enrolled = 1) 
         GROUP BY em_sj_id) AS a 
        ON [e-request.ereq_sj_id] = a.em_sj_id 
     RIGHT OUTER JOIN subjects 
        ON subjects.sj_id = [e-request.ereq_sj_id] 
         AND a.count < subjects.sj_max_enrollment_no 
         AND [e-request].ereq_id = @erequestID 

如何更改查詢以使其工作？該模式將顯示在底部

USE [EnrolDB] 
GO 
/****** Object: Table [dbo].[enrollment] Script Date: 4/28/2013 6:14:58 PM ******/ 
SET ANSI_NULLS ON 
GO 
SET QUOTED_IDENTIFIER ON 
GO 
CREATE TABLE [dbo].[enrollment](
    [em_st_id] [int] NOT NULL, 
    [em_sj_id] [int] NOT NULL, 
    [em_order] [int] NOT NULL, 
    [em_semester] [int] NOT NULL, 
    [em_year] [int] NOT NULL, 
    [em_result] [float] NULL, 
    [em_enrolled] [bit] NOT NULL, 
CONSTRAINT [PK__tmp_ms_x__76502B66F97E750E] PRIMARY KEY CLUSTERED 
(
    [em_st_id] ASC, 
    [em_sj_id] ASC, 
    [em_order] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] 

GO 
/****** Object: Table [dbo].[e-request] Script Date: 4/28/2013 6:14:59 PM ******/ 
SET ANSI_NULLS ON 
GO 
SET QUOTED_IDENTIFIER ON 
GO 
CREATE TABLE [dbo].[e-request](
    [ereq_id] [int] NOT NULL, 
    [ereq_st_id] [int] NOT NULL, 
    [ereq_sj_id] [int] NOT NULL, 
    [ereq_reason] [nvarchar](max) NOT NULL, 
    [ereq_status] [nvarchar](10) NOT NULL, 
CONSTRAINT [PK_e-request] PRIMARY KEY CLUSTERED 
(
    [ereq_id] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] 

GO 
/****** Object: Table [dbo].[prerequisites] Script Date: 4/28/2013 6:14:59 PM ******/ 
SET ANSI_NULLS ON 
GO 
SET QUOTED_IDENTIFIER ON 
GO 
CREATE TABLE [dbo].[prerequisites](
    [pq_sj_id] [int] NOT NULL, 
    [pq_pq_sj_id] [int] NOT NULL, 
CONSTRAINT [PK_prerequisites] PRIMARY KEY CLUSTERED 
(
    [pq_sj_id] ASC, 
    [pq_pq_sj_id] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] 

GO 
/****** Object: Table [dbo].[student] Script Date: 4/28/2013 6:14:59 PM ******/ 
SET ANSI_NULLS ON 
GO 
SET QUOTED_IDENTIFIER ON 
GO 
CREATE TABLE [dbo].[student](
    [st_id] [int] NOT NULL, 
    [st_first_name] [nvarchar](50) NOT NULL, 
    [st_mid_name] [nvarchar](50) NULL, 
    [st_last_name] [nvarchar](50) NULL, 
PRIMARY KEY CLUSTERED 
(
    [st_id] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] 

GO 
/****** Object: Table [dbo].[subjects] Script Date: 4/28/2013 6:14:59 PM ******/ 
SET ANSI_NULLS ON 
GO 
SET QUOTED_IDENTIFIER ON 
GO 
CREATE TABLE [dbo].[subjects](
    [sj_id] [int] NOT NULL, 
    [sj_name] [nvarchar](64) NOT NULL, 
    [sJ_descr] [nvarchar](1024) NULL, 
    [sj_max_enrollment_no] [int] NULL, 
    [sj_avail] [bit] NULL, 
PRIMARY KEY CLUSTERED 
(
    [sj_id] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] 

GO 
/****** Object: Table [dbo].[Table] Script Date: 4/28/2013 6:14:59 PM ******/ 
SET ANSI_NULLS ON 
GO 
SET QUOTED_IDENTIFIER ON 
GO 
CREATE TABLE [dbo].[Table](
    [pq_sj_id] [int] NOT NULL, 
    [pq_pq_sj_id] [int] NOT NULL, 
PRIMARY KEY CLUSTERED 
(
    [pq_sj_id] ASC, 
    [pq_pq_sj_id] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] 

GO 
ALTER TABLE [dbo].[enrollment] WITH CHECK ADD CONSTRAINT [FK_enrollment_student] FOREIGN KEY([em_st_id]) 
REFERENCES [dbo].[student] ([st_id]) 
GO 
ALTER TABLE [dbo].[enrollment] CHECK CONSTRAINT [FK_enrollment_student] 
GO 
ALTER TABLE [dbo].[enrollment] WITH CHECK ADD CONSTRAINT [FK_enrollment_subject] FOREIGN KEY([em_sj_id]) 
REFERENCES [dbo].[subjects] ([sj_id]) 
GO 
ALTER TABLE [dbo].[enrollment] CHECK CONSTRAINT [FK_enrollment_subject] 
GO 
ALTER TABLE [dbo].[prerequisites] WITH CHECK ADD CONSTRAINT [FK_prerequisites_subjects] FOREIGN KEY([pq_sj_id]) 
REFERENCES [dbo].[subjects] ([sj_id]) 
GO 
ALTER TABLE [dbo].[prerequisites] CHECK CONSTRAINT [FK_prerequisites_subjects] 
GO 
ALTER TABLE [dbo].[prerequisites] WITH CHECK ADD CONSTRAINT [FK_prerequisites_subjects2] FOREIGN KEY([pq_pq_sj_id]) 
REFERENCES [dbo].[subjects] ([sj_id]) 
GO 
ALTER TABLE [dbo].[prerequisites] CHECK CONSTRAINT [FK_prerequisites_subjects2] 
GO 

Answer 1

變化從[e-request.ereq_sj_id]到[e-request].ereq_sj_id