How do I use CREATE OR REPLACE?

Question

Am I correct in understanding that CREATE OR REPLACE basically means "if the object exists, drop it, then create it either way?"

If so, what am I doing wrong? This works:

CREATE TABLE foo (id NUMBER,
title VARCHAR2(4000) DEFAULT 'Default Title')

And this doesn't (ORA-00922: missing or invalid option):

CREATE OR REPLACE TABLE foo (id NUMBER,
title VARCHAR2(4000) DEFAULT 'Default Title')

Am I doing something stupid? I don't seem to be able to find much documentation about this syntax.

Answer 1

There is no create or replace table in Oracle.

You must:

DROP TABLE foo;
CREATE TABLE foo (....);

Answer 2

So I've been using this and it has worked very well: - it works more like a DROP IF EXISTS but gets the job done

DECLARE
       VE_TABLENOTEXISTS EXCEPTION;
PRAGMA EXCEPTION_INIT(VE_TABLENOTEXISTS, -942);


    PROCEDURE DROPTABLE(PIS_TABLENAME IN VARCHAR2) IS
              VS_DYNAMICDROPTABLESQL VARCHAR2(1024);
                    BEGIN
                       VS_DYNAMICDROPTABLESQL := 'DROP TABLE ' || PIS_TABLENAME;  
                    EXECUTE IMMEDIATE VS_DYNAMICDROPTABLESQL;

                    EXCEPTION
                        WHEN VE_TABLENOTEXISTS THEN
                             DBMS_OUTPUT.PUT_LINE(PIS_TABLENAME || ' NOT EXIST, SKIPPING....');
                        WHEN OTHERS THEN
                             DBMS_OUTPUT.PUT_LINE(SQLERRM);
                    RAISE;
                    END DROPTABLE;

    BEGIN
      DROPTABLE('YOUR_TABLE_HERE');
END DROPTABLE;
/   

Hope this helps Also reference: PLS-00103 Error in PL/SQL Developer

Answer 3

If this is for MS SQL.. The following code will always run no matter what if the table exist already or not.

if object_id('mytablename') is not null //has the table been created already in the db
Begin
     drop table mytablename
End

Create table mytablename (...

Answer 4

A usefull procedure for oracle databases without using exeptions (under circumstances you have to replace user_tables with dba_tables and/or constrain the tablespace in the query):

create or replace procedure NG_DROP_TABLE(tableName varchar2)
is
   c int;
begin
   select count(*) into c from user_tables where table_name = upper(tableName);
   if c = 1 then
      execute immediate 'drop table '||tableName;
   end if;
end;

Answer 5

'Create or replace table' is not possible. As others stated, you can write a procedure and/or use begin execute immediately (...). Because I don't see an answer with how to (re)create the table, I putted a script as an answer.

PS: in line of what jeffrey-kemp mentioned: this beneath script will NOT save data that is already present in the table you are going to drop. Because of the risk of loosing data, at our company it is only allowed to alter existing tables on the production environment, and it is not allowed to drop tables. By using the drop table statement, sooner or later you will get the company police standing at your desk.

--Create the table 'A_TABLE_X', and drop the table in case it already is present
BEGIN
EXECUTE IMMEDIATE 
'
CREATE TABLE A_TABLE_X
(
COLUMN1 NUMBER(15,0),
COLUMN2  VARCHAR2(255 CHAR),
COLUMN3  VARCHAR2(255 CHAR)
)';

EXCEPTION
WHEN OTHERS THEN
  IF SQLCODE != -955 THEN -- ORA-00955: object name already used
     EXECUTE IMMEDIATE 'DROP TABLE A_TABLE_X';
  END IF;
END;

Answer 6

If you are doing in code then first check for table in database by using query SELECT table_name FROM user_tables WHERE table_name = 'XYZ'

if record found then truncate table otherwise create Table

Work like Create or Replace.