I've got a database where I have to avoid placing replicates. The needs are:

For that subset of rows with matching column 1, there cannot be any that have a similar column 2.

For that subset of rows with matching column 1, there cannot be any that have a similar column 3 and 4.

I am a new comer to SQL so it is possible to method of setting these associations after i produce the database (create table) or must i perform a choose and do these inspections by hand before placing in to the table?

Essentially, you'll need the column 1 and a pair of to become unique, as well as posts 1,3 and 4 to become unique. Then when you produce the table, you should use two UNIQUE constaints:

CREATE TABLE tbl (
  col1 varchar(255),
  col2 varchar(255),
  col3 varchar(255),
  col4 varchar(255),
  CONSTRAINT uc_first UNIQUE(col1, col2),
  CONSTRAINT uc_second UNIQUE(col1, col3, col4)
)

Just to obtain the ball moving ...

Would you return immediately after the place and remove copied rows in line with the contraints you pointed out?