How to use NOT EXISTS with COMPOSITE KEYS in SQL for inserting data from POJO

I am using DB2 DBMS.

Scenario 1:

myTable has a composite key (key1, key2) where both key1 and key2 are foreign keys from yourTable.

I want to insert new data from yourTable into myTable, but only if the key1, key2 combination does not already exist in myTable.

insert into myT开发者_StackOverflow中文版able(key1, key2, someData)
values(x, y, z)
where NOT EXISTS (want to check if composite key is not already present)

Scenario 2:

I put data into a java object from yourTable with properties data1, data2, and data.

I want to insert the above data with the check as in Scenario1. data1 + data2 should not already be present in myTable.

How do I achieve this? I don't think we can use a SELECT statement inside the insert statement.

insert into myTable(key1, key2, data)
values(data1, data2, data)
where (data1 + data2 are already not present in myTable)

How can I achieve this?

insert into mytable(...)
select ...
from yourtable y
left join mytable m
on y.key1 = m.key1 and y.key2 = m.key2
where m.key is null

or

insert into mytable(...)
select ...
from yourtable y
where not exists (select 1 from mytable m where y.key1 = m.key1 and y.key2 = m.key2)

for your 2nd scenario, it'd look similar to the above query

insert into mytable(...)
select ...
where not exists (select 1 from mytable m where javakey1 = m.key1 and javakey2 = m.key2)

insert into mySchema.NIK(DATA1, DATA2, DATA) select 'C','3','MY' FROM SYSIBM.DUAL where not exists (select 1 from mySchema.NIK A where 'C' = A.DATA1 and '3' = A.DATA2)

if the data 'c' '3' already exists then above query will result in an empty table.