Question

I have written a stored procedure where a table name and database name collect
using cursor from different two tables.
But my problem is when I run a query to find out a table exists in a database or not, then show a error.
Now how can I run the query and store output into a variable?

Declare @table_exist nvarchar(200),@val1 nvarchar(200),@return1 nvarchar(200);
  SET @table_exist= 
    'SELECT 1 FROM '+@db_name+'.sys.tables 
    where name='+@table_name+'';
  EXEC sp_executesql @table_exist,@return1 OUTPUT;  
  select @return1;  

ERROR:

Invalid column name 'table name'

Answer 1

You should use quotename when building dynamic query:

   SET @table_exist= 
     'SELECT 1 FROM '+ quotename(@db_name)+'.sys.tables 
     where name='+quotename(@table_name)+'';

When facing such an error the best would be to print @table_exists and see what is actually built.

I haven’t looked properly at your query. You are missing apostrophes:

   SET @table_exist= 
     'SELECT 1 FROM '+ quotename(@db_name)+'.sys.tables 
     where name=''' + @table_name +'''';

UPDATE:

When using output variable you should set it in a query:

  SET @table_exist= 
    'SELECT @return1 = 1 FROM ' + quotename(@db_name) + '.sys.tables 
    where name='''+@table_name+'''';

To prevent result set from returning to client, create temporary table and insert result set into it. In this case this will leave only one result set, the result of select @return1:

  declare @tbl table (exist bit)
  insert into @tbl
  EXEC sp_executesql @table_exist, N'@return1 nvarchar(200) out', @return1 OUT;
  select @return1;