新增数据表或字段

判断表是否存在，如果存在则删除

declare
num number;
begin
select count(1) into num from user_tables where TABLE_NAME = 'BOOKING_INFO';
if   num=1   then
execute immediate 'drop table BOOKING_INFO';
end   if;
END;
/

判断表是字段是否存在，如果存在则删除

declare
num number;
begin
select count(1) into num From All_Tab_Columns Where Table_Name='BOOKING_INFO' And Column_Name='IMPORT_STATUS';
if   num=1   then
execute immediate 'alter table BOOKING_INFO drop (IMPORT_STATUS)';
end   if;
End;
/

判断序列是否存在，如果存在则删除

declare
num number;
begin
SELECT count(1) into num FROM dba_sequences where SEQUENCE_NAME='EDI_LFC_SEND_SEQ';
if   num=1   then
execute immediate 'drop sequence EDI_LFC_SEND_SEQ';
end   if;
END;
/
--创建序列
CREATE SEQUENCE EDI_LFC_SEND_SEQ INCREMENT BY 1 MAXVALUE 99999 MINVALUE 1 CYCLE CACHE 20;