执行联接时SQL Server表出错

Question

I'm trying to perform a join between 4 tables schedule table, employee table, machine table and plate table.

Problem is, at schedule table its primary key is a date while on the rest of the table have their primary key as char. I'm trying to convert the primary key in table into char to make it the same as the one on the others but I don't know how. Here is what I have done so far

create table Machine
(
    MachineID char(5),
    MachineType varchar(10) NOT NULL,
    MachineStatus varchar(10)NOT NULL
)

create table Employee
(
    EmployeeID char(5) Primary Key,
    EmployeeName varchar(30) NOT NULL,
)

create table Plate
(
    PlateID char(5) Primary Key,
    PlateModel varchar(30) NOT NULL,
)

create table MachineSchedule
(
    DateSchedule date Primary Key,
)

here is my join

SELECT Employee.EmployeName, Plate.PlateModel, Machine.MachineID, Machine.MachineType, Machine.MachineStatus
FROM Employee, Plate, Machine
JOIN MachineSchedule
ON MachineSchedule.DateSchedule=Machine.MachineID;

and here is the error it gave Conversion failed when converting date and/or time from character string.

Answer 1

The table design and it's relation are not done properly. Based on this design and relation the simplest solution,i mean the query to make error free:

DROP TABLE [MachineSchedule];

Create The table

CREATE TABLE [dbo].[MachineSchedule](
    [DateSchedule] [date] NOT NULL,
    [MachineID] [char](5) NULL,
PRIMARY KEY CLUSTERED 
(
    [DateSchedule] 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

SET ANSI_PADDING OFF
GO

Changed Query

SELECT Employee.EmployeeName, Plate.PlateModel, Machine.MachineID, Machine.MachineType, Machine.MachineStatus
FROM Employee, Plate, Machine
JOIN MachineSchedule
ON MachineSchedule.MachineID = Machine.MachineID;

Answer 2

Your Table structure is incorrect, you should use integer datatype for primary key not char or datetime as its creates indexing and we can not join table on char and date datatype they never have same value; and lastly where is the join for other tables in from clause. there should be join condition for Employee, Plate, Machine.

and primary and foreign key constraints also missing

Answer 3

You think Date column=char column ?

Use with conver to char For example

On cast(m.id as char(20))=ma.id Or update column type