V Oraclu stavek ALTER TABLE določa, kako dodati, spremeniti, izpustiti ali izbrisati stolpce v tabeli. Uporablja se tudi za preimenovanje tabele.
Kako dodati stolpec v tabelo
Sintaksa:
ALTER TABLE table_name ADD column_name column-definition;
primer:
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Upoštevajte, da že obstoječe stranke tabele. Zdaj dodajte nov stolpec customer_age v tabelo customer.
ALTER TABLE customers ADD customer_age varchar2(50);
Zdaj bo v tabelo strank dodan nov stolpec 'customer_age'.
Kako dodati več stolpcev v obstoječo tabelo
Sintaksa:
ALTER TABLE table_name ADD (column_1 column-definition, column_2 column-definition, ... column_n column_definition);
Primer
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.
Kako spremeniti stolpec tabele
Sintaksa:
ALTER TABLE table_name MODIFY column_name column_type;
primer:
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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.
Kako spremeniti več stolpcev v tabeli
Sintaksa:
ALTER TABLE table_name MODIFY (column_1 column_type, column_2 column_type, ... column_n column_type);
primer:
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.
Kako spustiti stolpec tabele
Sintaksa:
ALTER TABLE table_name DROP COLUMN column_name;
primer:
ALTER TABLE customers DROP COLUMN customer_name;
This will drop the customer_name column from the table.
Kako preimenovati stolpec tabele
Sintaksa:
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ALTER TABLE table_name RENAME COLUMN old_name to new_name;
primer:
ALTER TABLE customers RENAME COLUMN customer_name to cname;
This will rename the column customer_name into cname.
Kako preimenovati tabelo
Sintaksa:
ALTER TABLE table_name RENAME TO new_table_name;
primer:
ALTER TABLE customers RENAME TO retailers;
This will rename the customer table into 'retailers' table.