Oracle alter table modify column Syntax example

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For complete tips on Oracle alter table syntax, see the book "Easy Oracle Jumpstart". Oracle provides "alter table" syntax to modify data columns in-place in this form:

alter table
table_name
modify
column_name datatype;

If you are brave you can use a single "alter table" syntax to modify multiple columns:

alter table
   table_name
modify
   (
   column1_name column1_datatype,
   column2_name column2_datatype,
   column3_name column3_datatype,
   column4_name column4_datatype
   );

Here are some examples of Oracle "alter table" syntax to modify data columns and note that you can add constraints like NOT NULL:

ALTER TABLE
   customer
MODIFY
   (
   cust_name varchar2(100) not null,
   cust_hair_color varchar2(20)
   )
;

We can also use Oracle "alter table" syntax in dynamic PL/SQL to modify data columns

BEGIN
SQL_STRING := 'ALTER TABLE '||:TABLE_NAME||' MODIFY '||:COLUMN_NAME||' VARCHAR2(100)';

. . .
END;

巴特西

Oracle alter table modify column Syntax example

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