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Create table emp
(id number(9), name varchar2(20),salary
number(9,2));
The table has 100 records after table created.Now i nee to
change id's Datatype is to be Varchar2(15). now
Alter table emp modify(id varchar2(15),name varchar2(20),
salary number(9,2));
Whether it will work or returns error? post answer with
explanation.
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Answer Posted / nilesh
It will not work,
If u have data in a table and u have to change data type
number to varchar2 then it will gives error, If u change
varchar2(100) column to char(200) it will work,
The number to varchar2 or varchar2 to number will not work
when u have data in table.
| Is This Answer Correct ? | 0 Yes | 2 No |
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Hi, I am new in oracle(SQL), could anyone help me in writing a correct SQL. Below is the table structure. Table: Subsc Fields: 1. Sub_no (this field will hold values of subscriber nos, for e.g. S111111, S222222, S333333, S444444, etc.) 2. s_status (this field will hold values for different status of subscriber, for e.g. 'A', 'S', 'C', etc.) 3. cus_id (this field will hold values of bill nos for e.g. 11111111, 22222222, 33333333, 44444444, etc.) Table: Bill Fields: 1. Bill_no this field will hold values of bill nos for e.g. 11111111, 22222222, 33333333, 44444444, etc.) 2. b_status = (this field will hold values for different status of bill for e.g. 'O', 'C', 'S', etc.) Note: 1. The Sub_no is a Primary key of Subsc table. 2. The cus_id is a foreign in Subsc table (referred from Bill_no field of Bill table) 3. The Bill_no field is the Primary key of Bill table. Query A --> I wrote a query to select cus_id/Bill_no which is in status open (b_status = 'O') and having more than two active subscriber (i.e. S_status = 'A') in it ( i.e. more the two subscribers in same bill). select s.cus_id from subsc s where exists (select 1 from bill where bill_no = s.cus_id and b_status = 'O') and s_status = 'A' group by s.cus_id having count(sub_no) = 2 Problem : The above query will give the cus_id (or rather bill_no) which are in open status (b_status ='O) and which are having TWO ACTIVE Subscribers (s_status ='A') in it. However, this query will also lists the cus_id/bill_no which are having more than TWO subscribers in it (but only two subscriber will be in Active status (s_status = 'A') and the others will be in s_status = 'C' or s_status = 'S'. Help needed: I want to write a query which will fetch ONLY the cus_id/bill_no which are in open status (b_status ='O') and which are having ONLY TWO ACTIVE subscribers (s_status ='A') in it. B--> If I include the sub_no in the above query then NO row are returned. select s.cus_id, s.sub_no from subsc s where exists (select 1 from bill where bill_no = s.cus_id and b_status = 'O') and s_status = 'A' group by s.cus_id, s.sub_no having count(sub_no) = 2 Help needed: I want to modify the above query which will fetch ONLY the cus_id/bill_no which are in open status (b_status ='O') and which are having ONLY TWO ACTIVE subscribers (s_status ='A') in it ALONG with the sub_no. Thanks a lot in advance. Regards, Nitin
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