批量插入数据出错，请指教

Question

declare @index int , @str varchar(4000)
set @index=4
while @index<100
begin
set @str='insert into T_tbMA_MADepartment(MADepartmentSystemID,MADepartmentCode,MADepartmentName) values(1,''000000000000'+right('00'+ltrim(@index),3)+',''Depart'+right('00'+ltrim(@index),3)+')'
exec(@str)
set @index=@index+1
end
go

Answer 1

declare @index int , @str varchar(4000) 
set @index=4 
while @index <100 
begin 
set @str='insert into T_tbMA_MADepartment(MADepartmentSystemID,MADepartmentCode,MADepartmentName) values(1,''000000000000'+right('00'+ltrim(@index),3)+''',''Depart'+right('00'+ltrim(@index),3)+''')' 
exec(@str) 
set @index=@index+1 
end 
go

Answer 2

declare @index int , @str varchar(4000)
set @index=4
while @index <100
begin
set @str='insert into T_tbMA_MADepartment(MADepartmentSystemID,MADepartmentCode,MADepartmentName) 
values(1,''000000000000'+right('00'+ltrim(@index),3)+''',''Depart'+right('00'+ltrim(@index),3)+''')'--少了引號
exec(@str)
set @index=@index+1
end
go

Answer 3

--最后一个字符的值少了个引号
insert into T_tbMA_MADepartment(MADepartmentSystemID,MADepartmentCode,MADepartmentName) values(1,'000000000000004,'Depart004)

Answer 4

declare @index int , @str varchar(4000) 
set @index=4 
while @index <100 
begin 
set @str='insert into T_tbMA_MADepartment(MADepartmentSystemID,MADepartmentCode,MADepartmentName) values(1,''000000000000'+right('00'+ltrim(@index),3)+''',''Depart'+''+right('00'+ltrim(@index),3)+''''+')' 
exec(@str) 
set @index=@index+1 
end 

Answer 5

set @str='insert into T_tbMA_MADepartment(MADepartmentSystemID,MADepartmentCode,MADepartmentName) 
values(1,''000000000000'+right('00'+ltrim(@index),3)+''',''Depart'+right('00'+ltrim(@index),3)+''')'--少了引號
为什么要加上红色标记处的引号阿？