You need to write/generate scripts that have the changes you made in them. For example if you add a few columns to the table the SQL for this might be:
ALTER TABLE dbo.doc_exa ADD column_b VARCHAR(20) NULL, column_c INT NULL ;
ALTER TABLE dbo.doc_exa ADD column_b VARCHAR(20) NULL, column_c INT NULL ; Depending on the toolsets you have and the databases you use, there are various products that will help automate the generation of code. For example, In the SQL server world you could use Visual Studio database projects or Redgate. Other platforms will have similar tools available.