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1How to deal with duplicates in database?
2CREATE TABLE IF NOT EXISTS login
3(
4    loginid SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
5    loginname CHAR(20) NOT NULL,
6    UNIQUE (loginname) 
7);
8	
9ALTER TABLE `TableName` ADD UNIQUE KEY (KeyOne, KeyTwo, ...);
10	
11select @ret_val = 0
12   If exists (select * from employee where last_name = @param_ln and first_name = @param_fn)
13       select @ret_val = -1
14    Else
15       -- your insert statement here
16
17   Select @ret_val