Update it the next □ Ideally, do not include the data in the table. We should fully consider the possible future needs in the table design process, to avoid future structure of the table bigger changes.
□ all DBMS allows columns to existing tables increases, but the increased data type of the column (as well as the use of NULL and DEFAULT) restrictions.
□ Many DBMS can not delete or change the columns in the table.
□ Most DBMS allow you to rename columns in the table.
□ Many DBMS restricted on the columns have been filled with data changes, almost no limit to the column is not populated with data. As can be seen, the existing table do not change are complex unity.
Use ALTER TABLE to change the table structure, must be given the following information:
□ given in the table name you want to change (the table must exist, otherwise an error) after ALTER TABLE;
□ What changes do lists.
