oracle insert data, prevent inserting duplicate records

Extract data from access table , calibration insert oracle table and prevent inserting duplicate records.
I'm way to achieve this is to insert one before each query oracle again, if this record does not exist on the insert, the insert does not already exist , but the efficiency is very low , to ask how to achieve high efficiency point of it ?
------ Solution ---------------------------------------- ----
you guide data or why ?
you are one of the operation ?
------ Solution ---------------------------------------- ----
set the primary key , which work on the validation to the oracle itself up .

If you want each field are not the same , then no way, you're one to compare the
------ Solution --------------- -----------------------------
recommended java inside checksum
------ Solution - ------------------------------------------
If it is not the primary key , but also you can set the field's uniqueness
------ Solution --------------------------------- -----------
there are ways , if the amount of data is not the case , you can put Curry data when the program starts to cached queries when the direct investigation on the line with reduced database interaction .
------ Solution ---------------------------------------- ----
can oracle table read into memory is judged
------ Solution --------------------- -----------------------
you do not know what it means repeating
two exactly the same data ?
two of the primary key has been ?
other ? ?
------ Solution ---------------------------------------- ----
like I have here , I was put into the process of executing statement package , into the cache , each read cache, only parameter values ​​are changing, so you do not always have to generate queries, executed once , read cache are behind the
------ Solution --------------------------- -----------------
I will judge every time you insert here is whether the record exists, through several non- empty fields judgment ; insert if it does not exist , it exists not operate , these are placed during
------ For reference only -------------------------- -------------
insert data to the oracle , when is my own generated primary key , so the primary key is certainly not going to repeat , that the operation of the inverted data is also performed twice can insert
------ For reference only --------------------------------- ------
because it is from the access to extract data in a table , and then inserted into the oracle of the three tables , primary keys are formatting requirements, so I wrote the code to generate the primary key

------ For reference only ---------------------------------- -----
is inverted data

------ For reference only ---------------------------------- -----
has been resolved, I am now oracle table first read a set in the collection , and then insert it in the set in judgment on it ,
------ For reference only ---------------------------------------
Will the next landlord , the problem I now experiencing , there are solutions you
------ For reference only --------------------------- ------------
moisture can not stand this CSDN said synchronization settings obvious primary key set wool ah ; said no , please answer when repeated Hold the Answer how all this can set the primary key is also used here to ask me