The Dative case is formed by putting the suffixes –(y)a , -(y)e according to the previous vowel of the word (vowel harmony). If the word ends to a vowel, then, the suffix becomes -ya or –ye, if not, then you just put –a or –e
a,ı,o,u------- -(-y)a e,i,ö,ü------- -(y)e