sql - 为什么这个动态 SQL 语句会失败？

Question

这没有任何问题:

select COLUMN_NAME,DATA_TYPE,CHARACTER_MAXIMUM_LENGTH,IS_NULLABLE 
from [AdventureWorks2012].INFORMATION_SCHEMA.COLUMNS WHERE table_name='employee';

但是，当它移动到动态语句时，它总是失败:

begin
DECLARE @sqlstatement VARCHAR(MAX);
DECLARE @TableName varchar(max)='employee';

set @sqlstatement='select COLUMN_NAME,DATA_TYPE,CHARACTER_MAXIMUM_LENGTH,IS_NULLABLE
from [AdventureWorks2012].INFORMATION_SCHEMA.COLUMNS WHERE table_name='+@TableName;
print (@sqlstatement);
EXECUTE(@sqlstatement);

end

错误说:无效的列名'employee'

Answer 1

你应该用单引号把它包起来，因为 table_name 列是字符串，

set @sqlstatement='select COLUMN_NAME,DATA_TYPE,CHARACTER_MAXIMUM_LENGTH,IS_NULLABLE
from [AdventureWorks2012].INFORMATION_SCHEMA.COLUMNS WHERE table_name='''+@TableName+'''';