How to set default value for column of new created table from select statement in 11g
I create a table in Oracle 11g with the default value for one of the columns. Syntax is:
create table xyz(emp number,ename varchar2(100),salary number default 0);
This created successfully. For some reasons I need to create another table with same old table structure and data. So I created a new table with name abc as
create table abc as select * from xyz.
Here "abc" created successfully with same structure and data as old table xyz. But for the column "salary" in old table "xyz" default value was set to "0". But in the newly created table "abc" the default value is not set.
This is all in Oracle 11g. Please tell me the reason why the default value was not set and how we can set this using select statement.
Answer
You can specify the constraints and defaults in a CREATE TABLE AS SELECT, but the syntax is as follows
create table t1 (id number default 1 not null);
insert into t1 (id) values (2);
create table t2 (id default 1 not null)
as select * from t1;
That is, it won't inherit the constraints from the source table/select. Only the data type (length/precision/scale) is determined by the select.