Teradata ALTER Table function

We can alter the column without dropping the table by using the following syntax:

Syntax for adding new column name to table

ALTER TABLE <tablename> ADD <new_col>  <data_type>;

Syntax to modify a column datatype length

ALTER TABLE <Table_Name>

ADD <Existing_Column_Name> <New_Data_Type(New_Length)>

Here are the results while applying above syntax for changing column's data type:

3558: Cannot alter the specified attribute(s) for f_name.

VARCHAR ( from VARCHAR(20) TO VARCHAR(22)) - successfully executed

INTEGER ( FROM INTEGER TO DECIMAL(15,0)) - gives syntax error - 3558

CHAR ( FROM CHAR (5) TO CHAR (7)) -  syntax error - 3558

TIMESTAMP ( FROM TIMESTAMP(0) TO TIMESTAMP(1) )- syntax error - 3558

DECIMAL (FROM DECIMAL(15,0) TO DECIMAL(15,1) )- syntax error - 3558

It proves that these procedure is limited to VARCHAR.

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