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create table t1 (E1 INTEGER NOT NULL, E2 INTEGER NOT NULL, E3 INTEGER NOT NULL, PRIMARY KEY(E1)
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insert into t1 VALUES(1,1,1), (2,2,1);
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select count(*) from t1 INNER JOIN (SELECT A.E1, A.E2, A.E3 FROM t1 AS A WHERE A.E3 = (SELECT MAX(B.E3) FROM t1 AS B WHERE A.E2 = B.E2)) AS THEMAX ON t1.E1 = THEMAX.E2 AND t1.E1 = t1.E2;
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explain select count(*) from t1 INNER JOIN (SELECT A.E1, A.E2, A.E3 FROM t1 AS A WHERE A.E3 = (SELECT MAX(B.E3) FROM t1 AS B WHERE A.E2 = B.E2)) AS THEMAX ON t1.E1 = THEMAX.E2 AND t1.E1 = t1.E2;
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insert into t1 values (1),(2);
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select * from ( select * from t1 union select * from t1) a,(select * from t1 union select * from t1) b;
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explain select * from ( select * from t1 union select * from t1) a,(select * from t1 union select * from t1) b;