Sybase Question: Download Questions PDF
Given a table which contains some rows with duplicate keys, how would you remove the duplicates?
Answer:
create temporary table with same table structure and then create unique index on this temporary table with option ignore_dup_row.
now insert data into temp table from the table in which duplicate records exists.
while inserting record into temp table, duplicate rows will get ingored.
Finally temp table will have unique records
Ex:
select distinct * from table_1 into temp_table_1
truncate table_1
insert into table_1
select * from temp_table_1
This is one of the ways to eliminate duplicates.
now insert data into temp table from the table in which duplicate records exists.
while inserting record into temp table, duplicate rows will get ingored.
Finally temp table will have unique records
Ex:
select distinct * from table_1 into temp_table_1
truncate table_1
insert into table_1
select * from temp_table_1
This is one of the ways to eliminate duplicates.
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