Answer / m. ravindar

To Change DataType of Column:
Sy: Alter Table <Table Name> Modify <ColumnName> <DataType>;
Ex: Alter Table Test Modify EmpId varchar(5);

Answer / ashish

o Change DataType of Column:
Sy: Alter Table <Table Name> Modify <ColumnName> <DataType>;
Ex: Alter Table Test Modify EmpId varchar(5);

Answer / guru

You can change the column data type using this query:

Alter table table_name modify column_name datatype(length)

For example:
Alter table user modify name char(30)
You can change column name using this query:

Alter table table_name change old_column_name
new_column_name datatype(length)

For example:
Alter table user change user user_name char(30)

If you want to change column name and data type in single
query, then you use this query:

Alter table table_name change old_column_name
new_column_name new_datatype(10)

For example:
Alter table user change name user_name char(30)

For more details visit,

http://www.phponwebsites.com/2013/12/mysql-change-column-name.html
(for change column name)

http://www.phponwebsites.com/2013/12/mysql-change-column-datatype.html(for
change column datatype)

Answer / nithya

To change the name of the column:

ALTER TABLE TABLENAME RENAME COLUMN OLD_COLUMN_NAME TO
NEW_COLUMN_NAME;

eg: alter table employee rename column emp_name to ename;

To change the datatype of a column:

ALTER TABLE TABLENAME MODIGY COLUMN_NAME NEW_DATA_TYPE;

eg: alter table employee modify ename varchar(50);

NOTE: u cannot modify column of a datatype from larger value
to smaller value.U can do it only if there is no data in ur
column.

eg: alter table employ_detail modify emp_addr varchar(5);

ORA-01441: cannot decrease column length because some value
is too big

alter table employ_detail modify emp_id number(2)

ORA-01440: column to be modified must be empty to decrease
precision or scale

Answer / aftab alam

to add new columns in databases


alter table <table name> add column <column name> datatype;

Answer / szsad

excuse mr pls
ALTER TABLE products ALTER COLUMN price TYPE numeric
(10,2);
uyah nanhi vhalta hai

Answer / yogesh verma

Hi This is yOgEsH....!!
By this query we can change the data type of particular column :

ALTER TABLE products ALTER COLUMN price TYPE numeric(10,2);

Answer / m. ravindar

To Change Name of Column:
Sy: Alter Table <Table Name> Change <Old ColumnName> <New
ColumnName>;
Ex: Alter Table Test Change EmpId EID varchar(5);

Answer / abhishek

ALTER TABLE `<tablename>` CHANGE `<old column>` `<new
column>` new datatype( length )

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