primary key

max no of primary keys in single table is 16

create table my_table1 (
     column_a1 integer not null,
     column_a2 integer not null,
     column_a3 integer not null,
     column_a4 integer not null,
     column_a5 integer not null,
     column_a6 integer not null,
     column_a7 integer not null,
     column_a8 integer not null,
     column_a9 integer not null,
     column_a10 integer not null,
     column_a11 integer not null,
     column_a12 integer not null,
     column_a13 integer not null,
     column_a14 integer not null,
     column_a15 integer not null,
     column_a16 integer not null,
     column_a17 integer not null,
    primary key (column_a1, column_a2, column_a3, column_a4,
 column_a5, column_a6, column_a7, column_a8, column_a9,
column_a10, column_a11, column_a12, column_a13, column_a14,
column_a15, column_a16)
);