SQLD(SQL 개발자) 기출 · JOIN

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1. 1.SELECT * FROM Mytesta a left
   outer join Mytestb b
   on a.col1 = b.col1
   union
   SELECT * FROM Mytesta a right
   outer join Mytestb b
   on a.col1 = b.col1;
2. 2.SELECT * FROM Mytesta a cross
   join Mytestb b
   on a.col1 = b.col1
3. 3.SELECT * FROM Mytesta a left
   outer join Mytestb b
   on a.col1 = b.col1
   union all
   SELECT * FROM Mytesta a left
   outer join Mytestb b
   on a.col1 = b.col1;
4. 4.SELECT * FROM Mytesta group by col1;