V systéme Oracle príkaz ALTER TABLE špecifikuje, ako pridať, upraviť, zrušiť alebo odstrániť stĺpce v tabuľke. Používa sa aj na premenovanie tabuľky.

Ako pridať stĺpec do tabuľky

Syntax:

 ALTER TABLE table_name ADD column_name column-definition; 

Príklad:

upcasting

Zvážte, že už existujúci stôl zákazníkov. Teraz pridajte nový stĺpec customer_age do tabuľky customers.

 ALTER TABLE customers ADD customer_age varchar2(50); 

Teraz bude do tabuľky zákazníkov pridaný nový stĺpec 'customer_age'.

Ako pridať viacero stĺpcov do existujúcej tabuľky

Syntax:

int parseint

 ALTER TABLE table_name ADD (column_1 column-definition, column_2 column-definition, ... column_n column_definition); 

Príklad

 ALTER TABLE customers ADD (customer_type varchar2(50), customer_address varchar2(50)); 

 Now, two columns customer_type and customer_address will be added in the table customers. 

Ako upraviť stĺpec tabuľky

Syntax:

 ALTER TABLE table_name MODIFY column_name column_type; 

Príklad:

 ALTER TABLE customers MODIFY customer_name varchar2(100) not null; 

 Now the column column_name in the customers table is modified to varchar2 (100) and forced the column to not allow null values. 

Ako upraviť viacero stĺpcov tabuľky

Syntax:

 ALTER TABLE table_name MODIFY (column_1 column_type, column_2 column_type, ... column_n column_type); 

Príklad:

 ALTER TABLE customers MODIFY (customer_name varchar2(100) not null, city varchar2(100)); 

 This will modify both the customer_name and city columns in the table. 

Ako zrušiť stĺpec tabuľky

Syntax:

čo je monitor

 ALTER TABLE table_name DROP COLUMN column_name; 

Príklad:

 ALTER TABLE customers DROP COLUMN customer_name; 

 This will drop the customer_name column from the table. 

Ako premenovať stĺpec tabuľky

Syntax:

 ALTER TABLE table_name RENAME COLUMN old_name to new_name; 

Príklad:

 ALTER TABLE customers RENAME COLUMN customer_name to cname; 

 This will rename the column customer_name into cname. 

Ako premenovať tabuľku

Syntax:

 ALTER TABLE table_name RENAME TO new_table_name; 

Príklad:

 ALTER TABLE customers RENAME TO retailers; 

 This will rename the customer table into 'retailers' table.