mysql-Modifying a table

A modified table name

ALTER TABLE old_table_name Rename [to] New_table_name

Eg:alter Table T_dept

RENAME tab_dept;

Two add fields

1) Add field at the last position of the table

ALTER TABLE table_name

ADD Property Name Property type

Eg:alter Table T_dept

ADD Descri varchar (20);

2) Add a field to the first position in the table

ALTER TABLE table_name

ADD Property Name property type first;

3) Add a field after the specified field in the table

ALTER TABLE table_name

ADD Property Name Property type

After property name;

Three delete fields

ALTER TABLE table_name

DROP attribute name;

Four modified fields

1) Modify the data type of the field

ALTER TABLE table_name

MODIFY Property name Data type

Eg:alter Table T_dept

Modify Deptno varchar (20);

2) Change the name of the field

ALTER TABLE table_name

Change old property name new property name old data type

Eg:alter Table T_dept

Change LOC location varchar (40);

3) Modify the name and attributes of the field at the same time

ALTER TABLE table_name

Change old property name new property name new data type

Eg:alter Table T_dept

Change LOC location varchar (20);

4) Modify the order of the fields

ALTER TABLE table_name

MODIFY Property name 1 data type first| After property name 2

Eg:alter Table T_dept

Modify Deptno Int (one) after dname;

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mysql-Modifying a table