auto increment and update required field.

hi friends..

suppose i have table with col. SrNo, Name, Rank.

SrNo column has set as primary key column and autoincrement set is on.

suppose there are 5 records sequentially i.e
1 abc 1
2 def 2
3 ddd 3
4 eee 4
5 rrr 5

now if i want to insert a new record as pqr and rank is 3, then it should be added to 3rd place in table and rank of next records should be incremented automatically by 1.

i.e new o/p should be
1 abc 1
2 def 2
3 pqr 3
4 ddd 4
5 eee 5
6 rrr 5

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please help me..how should my table structure for that and what should be query to insert new record.