mysql alter table add column example

1100 20 Empno ename job mgr hiredate sal comm deptno------------------------------------------------------------------------------7900 james clerk 7698 03-dec-81 950 307902 ford analyst 7566 03-dec-81 3000 207934 miller clerk 7782 23-jan-82 1300 10 14 rows selected. SQL>SQL> alter table emp2 add (3 gender varchar (10 ));

Alter table tablename add (column datatype [default value] [null/not null],...); Alter table tablename modify (column datatype [default value] [null/not null],...);

In the process of using a database, it is sometimes necessary to change its table structure, including changing the name of the field, or even changing the relationship between different database fields. The command that can achieve this change is alter, whose basic syntax is as follows:Altertabletable_namealter_spec[,alter_spec ...1: Delete Column Altertable "

Create a new table (using the structure of the current table) with the new column (s) included. Execute aINSERT INTO new_table SELECT (column1,..columnN) FROM current_table; Rename the current table Rename the new table using the name of the current

Label:MySQL how to properly change a large table structure (Alter table structure of a single columnHttp://blog.sina.com.cn/s/blog_445e807b0101egpf.htmlFound on the Internet a very helpful three-paragraph script, posted for reference, readers, make a note:## Script 1# Alter table