test/select6.test

# 2001 September 15
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing SELECT statements that contain
# subqueries in their FROM clause.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Omit this whole file if the library is build without subquery support.
ifcapable !subquery {
  finish_test
  return
}
set ::testprefix select6

do_test select6-1.0 {
  execsql {
    BEGIN;
    CREATE TABLE t1(x, y);
    INSERT INTO t1 VALUES(1,1);
    INSERT INTO t1 VALUES(2,2);
    INSERT INTO t1 VALUES(3,2);
    INSERT INTO t1 VALUES(4,3);
    INSERT INTO t1 VALUES(5,3);
    INSERT INTO t1 VALUES(6,3);
    INSERT INTO t1 VALUES(7,3);
    INSERT INTO t1 VALUES(8,4);
    INSERT INTO t1 VALUES(9,4);
    INSERT INTO t1 VALUES(10,4);
    INSERT INTO t1 VALUES(11,4);
    INSERT INTO t1 VALUES(12,4);
    INSERT INTO t1 VALUES(13,4);
    INSERT INTO t1 VALUES(14,4);
    INSERT INTO t1 VALUES(15,4);
    INSERT INTO t1 VALUES(16,5);
    INSERT INTO t1 VALUES(17,5);
    INSERT INTO t1 VALUES(18,5);
    INSERT INTO t1 VALUES(19,5);
    INSERT INTO t1 VALUES(20,5);
    COMMIT;
    SELECT DISTINCT y FROM t1 ORDER BY y;
  }
} {1 2 3 4 5}

do_test select6-1.1 {
  execsql2 {SELECT * FROM (SELECT x, y FROM t1 WHERE x<2)}
} {x 1 y 1}
do_test select6-1.2 {
  execsql {SELECT count(*) FROM (SELECT y FROM t1)}
} {20}
do_test select6-1.3 {
  execsql {SELECT count(*) FROM (SELECT DISTINCT y FROM t1)}
} {5}
do_test select6-1.4 {
  execsql {SELECT count(*) FROM (SELECT DISTINCT * FROM (SELECT y FROM t1))}
} {5}
do_test select6-1.5 {
  execsql {SELECT count(*) FROM (SELECT * FROM (SELECT DISTINCT y FROM t1))}
} {5}

do_test select6-1.6 {
  execsql {
    SELECT * 
    FROM (SELECT count(*),y FROM t1 GROUP BY y) AS a,
         (SELECT max(x),y FROM t1 GROUP BY y) as b
    WHERE a.y=b.y ORDER BY a.y
  }
} {1 1 1 1 2 2 3 2 4 3 7 3 8 4 15 4 5 5 20 5}
do_test select6-1.7 {
  execsql {
    SELECT a.y, a.[count(*)], [max(x)], [count(*)]
    FROM (SELECT count(*),y FROM t1 GROUP BY y) AS a,
         (SELECT max(x),y FROM t1 GROUP BY y) as b
    WHERE a.y=b.y ORDER BY a.y
  }
} {1 1 1 1 2 2 3 2 3 4 7 4 4 8 15 8 5 5 20 5}
do_test select6-1.8 {
  execsql {
    SELECT q, p, r
    FROM (SELECT count(*) as p , y as q FROM t1 GROUP BY y) AS a,
         (SELECT max(x) as r, y as s FROM t1 GROUP BY y) as b
    WHERE q=s ORDER BY s
  }
} {1 1 1 2 2 3 3 4 7 4 8 15 5 5 20}
do_test select6-1.9 {
  execsql {
    SELECT q, p, r, b.[min(x)+y]
    FROM (SELECT count(*) as p , y as q FROM t1 GROUP BY y) AS a,
         (SELECT max(x) as r, y as s, min(x)+y FROM t1 GROUP BY y) as b
    WHERE q=s ORDER BY s
  }
} {1 1 1 2 2 2 3 4 3 4 7 7 4 8 15 12 5 5 20 21}

do_test select6-2.0 {
  execsql {
    CREATE TABLE t2(a INTEGER PRIMARY KEY, b);
    INSERT INTO t2 SELECT * FROM t1;
    SELECT DISTINCT b FROM t2 ORDER BY b;
  }
} {1 2 3 4 5}
do_test select6-2.1 {
  execsql2 {SELECT * FROM (SELECT a, b FROM t2 WHERE a<2)}
} {a 1 b 1}
do_test select6-2.2 {
  execsql {SELECT count(*) FROM (SELECT b FROM t2)}
} {20}
do_test select6-2.3 {
  execsql {SELECT count(*) FROM (SELECT DISTINCT b FROM t2)}
} {5}
do_test select6-2.4 {
  execsql {SELECT count(*) FROM (SELECT DISTINCT * FROM (SELECT b FROM t2))}
} {5}
do_test select6-2.5 {
  execsql {SELECT count(*) FROM (SELECT * FROM (SELECT DISTINCT b FROM t2))}
} {5}

do_test select6-2.6 {
  execsql {
    SELECT * 
    FROM (SELECT count(*),b FROM t2 GROUP BY b) AS a,
         (SELECT max(a),b FROM t2 GROUP BY b) as b
    WHERE a.b=b.b ORDER BY a.b
  }
} {1 1 1 1 2 2 3 2 4 3 7 3 8 4 15 4 5 5 20 5}
do_test select6-2.7 {
  execsql {
    SELECT a.b, a.[count(*)], [max(a)], [count(*)]
    FROM (SELECT count(*),b FROM t2 GROUP BY b) AS a,
         (SELECT max(a),b FROM t2 GROUP BY b) as b
    WHERE a.b=b.b ORDER BY a.b
  }
} {1 1 1 1 2 2 3 2 3 4 7 4 4 8 15 8 5 5 20 5}
do_test select6-2.8 {
  execsql {
    SELECT q, p, r
    FROM (SELECT count(*) as p , b as q FROM t2 GROUP BY b) AS a,
         (SELECT max(a) as r, b as s FROM t2 GROUP BY b) as b
    WHERE q=s ORDER BY s
  }
} {1 1 1 2 2 3 3 4 7 4 8 15 5 5 20}
do_test select6-2.9 {
  execsql {
    SELECT a.q, a.p, b.r
    FROM (SELECT count(*) as p , b as q FROM t2 GROUP BY q) AS a,
         (SELECT max(a) as r, b as s FROM t2 GROUP BY s) as b
    WHERE a.q=b.s ORDER BY a.q
  }
} {1 1 1 2 2 3 3 4 7 4 8 15 5 5 20}

do_test select6-3.1 {
  execsql2 {
    SELECT * FROM (SELECT * FROM (SELECT * FROM t1 WHERE x=3));
  }
} {x 3 y 2}
do_test select6-3.2 {
  execsql {
    SELECT * FROM
      (SELECT a.q, a.p, b.r
       FROM (SELECT count(*) as p , b as q FROM t2 GROUP BY q) AS a,
            (SELECT max(a) as r, b as s FROM t2 GROUP BY s) as b
       WHERE a.q=b.s ORDER BY a.q)
    ORDER BY "a.q"
  }
} {1 1 1 2 2 3 3 4 7 4 8 15 5 5 20}
do_test select6-3.3 {
  execsql {
    SELECT a,b,a+b FROM (SELECT avg(x) as 'a', avg(y) as 'b' FROM t1)
  }
} {10.5 3.7 14.2}
do_test select6-3.4 {
  execsql {
    SELECT a,b,a+b FROM (SELECT avg(x) as 'a', avg(y) as 'b' FROM t1 WHERE y=4)
  }
} {11.5 4.0 15.5}
do_test select6-3.5 {
  execsql {
    SELECT x,y,x+y FROM (SELECT avg(a) as 'x', avg(b) as 'y' FROM t2 WHERE a=4)
  }
} {4.0 3.0 7.0}
do_test select6-3.6 {
  execsql {
    SELECT a,b,a+b FROM (SELECT avg(x) as 'a', avg(y) as 'b' FROM t1)
    WHERE a>10
  }
} {10.5 3.7 14.2}
do_test select6-3.7 {
  execsql {
    SELECT a,b,a+b FROM (SELECT avg(x) as 'a', avg(y) as 'b' FROM t1)
    WHERE a<10
  }
} {}
do_test select6-3.8 {
  execsql {
    SELECT a,b,a+b FROM (SELECT avg(x) as 'a', avg(y) as 'b' FROM t1 WHERE y=4)
    WHERE a>10
  }
} {11.5 4.0 15.5}
do_test select6-3.9 {
  execsql {
    SELECT a,b,a+b FROM (SELECT avg(x) as 'a', avg(y) as 'b' FROM t1 WHERE y=4)
    WHERE a<10
  }
} {}
do_test select6-3.10 {
  execsql {
    SELECT a,b,a+b FROM (SELECT avg(x) as 'a', y as 'b' FROM t1 GROUP BY b)
    ORDER BY a
  }
} {1.0 1 2.0 2.5 2 4.5 5.5 3 8.5 11.5 4 15.5 18.0 5 23.0}
do_test select6-3.11 {
  execsql {
    SELECT a,b,a+b FROM 
       (SELECT avg(x) as 'a', y as 'b' FROM t1 GROUP BY b)
    WHERE b<4 ORDER BY a
  }
} {1.0 1 2.0 2.5 2 4.5 5.5 3 8.5}
do_test select6-3.12 {
  execsql {
    SELECT a,b,a+b FROM 
       (SELECT avg(x) as 'a', y as 'b' FROM t1 GROUP BY b HAVING a>1)
    WHERE b<4 ORDER BY a
  }
} {2.5 2 4.5 5.5 3 8.5}
do_test select6-3.13 {
  execsql {
    SELECT a,b,a+b FROM 
       (SELECT avg(x) as 'a', y as 'b' FROM t1 GROUP BY b HAVING a>1)
    ORDER BY a
  }
} {2.5 2 4.5 5.5 3 8.5 11.5 4 15.5 18.0 5 23.0}
do_test select6-3.14 {
  execsql {
    SELECT [count(*)],y FROM (SELECT count(*), y FROM t1 GROUP BY y)
    ORDER BY [count(*)]
  }
} {1 1 2 2 4 3 5 5 8 4}
do_test select6-3.15 {
  execsql {
    SELECT [count(*)],y FROM (SELECT count(*), y FROM t1 GROUP BY y)
    ORDER BY y
  }
} {1 1 2 2 4 3 8 4 5 5}

do_test select6-4.1 {
  execsql {
    SELECT a,b,c FROM 
      (SELECT x AS 'a', y AS 'b', x+y AS 'c' FROM t1 WHERE y=4)
    WHERE a<10 ORDER BY a;
  }
} {8 4 12 9 4 13}
do_test select6-4.2 {
  execsql {
    SELECT y FROM (SELECT DISTINCT y FROM t1) WHERE y<5 ORDER BY y
  }
} {1 2 3 4}
do_test select6-4.3 {
  execsql {
    SELECT DISTINCT y FROM (SELECT y FROM t1) WHERE y<5 ORDER BY y
  }
} {1 2 3 4}
do_test select6-4.4 {
  execsql {
    SELECT avg(y) FROM (SELECT DISTINCT y FROM t1) WHERE y<5 ORDER BY y
  }
} {2.5}
do_test select6-4.5 {
  execsql {
    SELECT avg(y) FROM (SELECT DISTINCT y FROM t1 WHERE y<5) ORDER BY y
  }
} {2.5}

do_test select6-5.1 {
  execsql {
    SELECT a,x,b FROM
      (SELECT x+3 AS 'a', x FROM t1 WHERE y=3) AS 'p',
      (SELECT x AS 'b' FROM t1 WHERE y=4) AS 'q'
    WHERE a=b
    ORDER BY a
  }
} {8 5 8 9 6 9 10 7 10}
do_test select6-5.2 {
  execsql {
    SELECT a,x,b FROM
      (SELECT x+3 AS 'a', x FROM t1 WHERE y=3),
      (SELECT x AS 'b' FROM t1 WHERE y=4)
    WHERE a=b
    ORDER BY a
  }
} {8 5 8 9 6 9 10 7 10}

# Tests of compound sub-selects
#
do_test select6-6.1 {
  execsql {
    DELETE FROM t1 WHERE x>4;
    SELECT * FROM t1
  }
} {1 1 2 2 3 2 4 3}
ifcapable compound {
  do_test select6-6.2 {
    execsql {
      SELECT * FROM (
        SELECT x AS 'a' FROM t1 UNION ALL SELECT x+10 AS 'a' FROM t1
      ) ORDER BY a;
    }
  } {1 2 3 4 11 12 13 14}
  do_test select6-6.3 {
    execsql {
      SELECT * FROM (
        SELECT x AS 'a' FROM t1 UNION ALL SELECT x+1 AS 'a' FROM t1
      ) ORDER BY a;
    }
  } {1 2 2 3 3 4 4 5}
  do_test select6-6.4 {
    execsql {
      SELECT * FROM (
        SELECT x AS 'a' FROM t1 UNION SELECT x+1 AS 'a' FROM t1
      ) ORDER BY a;
    }
  } {1 2 3 4 5}
  do_test select6-6.5 {
    execsql {
      SELECT * FROM (
        SELECT x AS 'a' FROM t1 INTERSECT SELECT x+1 AS 'a' FROM t1
      ) ORDER BY a;
    }
  } {2 3 4}
  do_test select6-6.6 {
    execsql {
      SELECT * FROM (
        SELECT x AS 'a' FROM t1 EXCEPT SELECT x*2 AS 'a' FROM t1
      ) ORDER BY a;
    }
  } {1 3}
} ;# ifcapable compound

# Subselects with no FROM clause
#
do_test select6-7.1 {
  execsql {
    SELECT * FROM (SELECT 1)
  }
} {1}
do_test select6-7.2 {
  execsql {
    SELECT c,b,a,* FROM (SELECT 1 AS 'a', 2 AS 'b', 'abc' AS 'c')
  }
} {abc 2 1 1 2 abc}
do_test select6-7.3 {
  execsql {
    SELECT c,b,a,* FROM (SELECT 1 AS 'a', 2 AS 'b', 'abc' AS 'c' WHERE 0)
  }
} {}
do_test select6-7.4 {
  execsql2 {
    SELECT c,b,a,* FROM (SELECT 1 AS 'a', 2 AS 'b', 'abc' AS 'c' WHERE 1)
  }
} {c abc b 2 a 1 a 1 b 2 c abc}

# The remaining tests in this file depend on the EXPLAIN keyword.
# Skip these tests if EXPLAIN is disabled in the current build.
#
ifcapable {!explain} {
  finish_test
  return
}

# The following procedure compiles the SQL given as an argument and returns
# TRUE if that SQL uses any transient tables and returns FALSE if no
# transient tables are used.  This is used to make sure that the
# sqliteFlattenSubquery() routine in select.c is doing its job.
#
proc is_flat {sql} {
  return [expr 0>[lsearch [execsql "EXPLAIN $sql"] OpenEphemeral]]
}

# Check that the flattener works correctly for deeply nested subqueries
# involving joins.
#
do_test select6-8.1 {
  execsql {
    BEGIN;
    CREATE TABLE t3(p,q);
    INSERT INTO t3 VALUES(1,11);
    INSERT INTO t3 VALUES(2,22);
    CREATE TABLE t4(q,r);
    INSERT INTO t4 VALUES(11,111);
    INSERT INTO t4 VALUES(22,222);
    COMMIT;
    SELECT * FROM t3 NATURAL JOIN t4;
  }
} {1 11 111 2 22 222}
do_test select6-8.2 {
  execsql {
    SELECT y, p, q, r FROM
       (SELECT t1.y AS y, t2.b AS b FROM t1, t2 WHERE t1.x=t2.a) AS m,
       (SELECT t3.p AS p, t3.q AS q, t4.r AS r FROM t3 NATURAL JOIN t4) as n
    WHERE  y=p
  }
} {1 1 11 111 2 2 22 222 2 2 22 222}
# If view support is omitted from the build, then so is the query 
# "flattener". So omit this test and test select6-8.6 in that case.
ifcapable view {
do_test select6-8.3 {
  is_flat {
    SELECT y, p, q, r FROM
       (SELECT t1.y AS y, t2.b AS b FROM t1, t2 WHERE t1.x=t2.a) AS m,
       (SELECT t3.p AS p, t3.q AS q, t4.r AS r FROM t3 NATURAL JOIN t4) as n
    WHERE  y=p
  }
} {1}
} ;# ifcapable view
do_test select6-8.4 {
  execsql {
    SELECT DISTINCT y, p, q, r FROM
       (SELECT t1.y AS y, t2.b AS b FROM t1, t2 WHERE t1.x=t2.a) AS m,
       (SELECT t3.p AS p, t3.q AS q, t4.r AS r FROM t3 NATURAL JOIN t4) as n
    WHERE  y=p
  }
} {1 1 11 111 2 2 22 222}
do_test select6-8.5 {
  execsql {
    SELECT * FROM 
      (SELECT y, p, q, r FROM
         (SELECT t1.y AS y, t2.b AS b FROM t1, t2 WHERE t1.x=t2.a) AS m,
         (SELECT t3.p AS p, t3.q AS q, t4.r AS r FROM t3 NATURAL JOIN t4) as n
      WHERE  y=p) AS e,
      (SELECT r AS z FROM t4 WHERE q=11) AS f
    WHERE e.r=f.z
  }
} {1 1 11 111 111}
ifcapable view {
do_test select6-8.6 {
  is_flat {
    SELECT * FROM 
      (SELECT y, p, q, r FROM
         (SELECT t1.y AS y, t2.b AS b FROM t1, t2 WHERE t1.x=t2.a) AS m,
         (SELECT t3.p AS p, t3.q AS q, t4.r AS r FROM t3 NATURAL JOIN t4) as n
      WHERE  y=p) AS e,
      (SELECT r AS z FROM t4 WHERE q=11) AS f
    WHERE e.r=f.z
  }
} {1}
} ;# ifcapable view

# Ticket #1634
#
do_test select6-9.1 {
  execsql {
    SELECT a.x, b.x FROM t1 AS a, (SELECT x FROM t1 LIMIT 2) AS b
     ORDER BY 1, 2
  }
} {1 1 1 2 2 1 2 2 3 1 3 2 4 1 4 2}
do_test select6-9.2 {
  execsql {
    SELECT x FROM (SELECT x FROM t1 LIMIT 2);
  }
} {1 2}
do_test select6-9.3 {
  execsql {
    SELECT x FROM (SELECT x FROM t1 LIMIT 2 OFFSET 1);
  }
} {2 3}
do_test select6-9.4 {
  execsql {
    SELECT x FROM (SELECT x FROM t1) LIMIT 2;
  }
} {1 2}
do_test select6-9.5 {
  execsql {
    SELECT x FROM (SELECT x FROM t1) LIMIT 2 OFFSET 1;
  }
} {2 3}
do_test select6-9.6 {
  execsql {
    SELECT x FROM (SELECT x FROM t1 LIMIT 2) LIMIT 3;
  }
} {1 2}
do_test select6-9.7 {
  execsql {
    SELECT x FROM (SELECT x FROM t1 LIMIT -1) LIMIT 3;
  }
} {1 2 3}
do_test select6-9.8 {
  execsql {
    SELECT x FROM (SELECT x FROM t1 LIMIT -1);
  }
} {1 2 3 4}
do_test select6-9.9 {
  execsql {
    SELECT x FROM (SELECT x FROM t1 LIMIT -1 OFFSET 1);
  }
} {2 3 4}
do_test select6-9.10 {
  execsql {
    SELECT x, y FROM (SELECT x, (SELECT 10+x) y FROM t1 LIMIT -1 OFFSET 1);
  }
} {2 12 3 13 4 14}
do_test select6-9.11 {
  execsql {
    SELECT x, y FROM (SELECT x, (SELECT 10)+x y FROM t1 LIMIT -1 OFFSET 1);
  }
} {2 12 3 13 4 14}


#-------------------------------------------------------------------------
# Test that if a UNION ALL sub-query that would otherwise be eligible for
# flattening consists of two or more SELECT statements that do not all 
# return the same number of result columns, the error is detected.
#
do_execsql_test 10.1 {
  CREATE TABLE t(i,j,k);
  CREATE TABLE j(l,m);
  CREATE TABLE k(o);
}

set err [list 1 {SELECTs to the left and right of UNION ALL do not have the same number of result columns}]

do_execsql_test 10.2 {
  SELECT * FROM (SELECT * FROM t), j;
}
do_catchsql_test 10.3 {
  SELECT * FROM t UNION ALL SELECT * FROM j
} $err
do_catchsql_test 10.4 {
  SELECT * FROM (SELECT i FROM t UNION ALL SELECT l, m FROM j)
} $err
do_catchsql_test 10.5 {
  SELECT * FROM (SELECT j FROM t UNION ALL SELECT * FROM j)
} $err
do_catchsql_test 10.6 {
  SELECT * FROM (SELECT * FROM t UNION ALL SELECT * FROM j)
} $err
do_catchsql_test 10.7 {
  SELECT * FROM (
    SELECT * FROM t UNION ALL 
    SELECT l,m,l FROM j UNION ALL
    SELECT * FROM k
  )
} $err
do_catchsql_test 10.8 {
  SELECT * FROM (
    SELECT * FROM k UNION ALL
    SELECT * FROM t UNION ALL 
    SELECT l,m,l FROM j 
  )
} $err

# 2015-02-09 Ticket [2f7170d73bf9abf80339187aa3677dce3dbcd5ca]
# "misuse of aggregate" error if aggregate column from FROM
# subquery is used in correlated subquery 
#
do_execsql_test 11.1 {
  DROP TABLE IF EXISTS t1;
  CREATE TABLE t1(w INT, x INT);
  INSERT INTO t1(w,x)
   VALUES(1,10),(2,20),(3,30),
         (2,21),(3,31),
         (3,32);
  CREATE INDEX t1wx ON t1(w,x);

  DROP TABLE IF EXISTS t2;
  CREATE TABLE t2(w INT, y VARCHAR(8));
  INSERT INTO t2(w,y) VALUES(1,'one'),(2,'two'),(3,'three'),(4,'four');
  CREATE INDEX t2wy ON t2(w,y);

  SELECT cnt, xyz, (SELECT y FROM t2 WHERE w=cnt), '|'
    FROM (SELECT count(*) AS cnt, w AS xyz FROM t1 GROUP BY 2)
   ORDER BY cnt, xyz;
} {1 1 one | 2 2 two | 3 3 three |}
do_execsql_test 11.2 {
  SELECT cnt, xyz, lower((SELECT y FROM t2 WHERE w=cnt)), '|'
    FROM (SELECT count(*) AS cnt, w AS xyz FROM t1 GROUP BY 2)
   ORDER BY cnt, xyz;
} {1 1 one | 2 2 two | 3 3 three |}
do_execsql_test 11.3 {
  SELECT cnt, xyz, '|'
    FROM (SELECT count(*) AS cnt, w AS xyz FROM t1 GROUP BY 2)
   WHERE (SELECT y FROM t2 WHERE w=cnt)!='two'
   ORDER BY cnt, xyz;
} {1 1 | 3 3 |}
do_execsql_test 11.4 {
  SELECT cnt, xyz, '|'
    FROM (SELECT count(*) AS cnt, w AS xyz FROM t1 GROUP BY 2)
   ORDER BY lower((SELECT y FROM t2 WHERE w=cnt));
} {1 1 | 3 3 | 2 2 |}
do_execsql_test 11.5 {
  SELECT cnt, xyz, 
         CASE WHEN (SELECT y FROM t2 WHERE w=cnt)=='two'
              THEN 'aaa' ELSE 'bbb'
          END, '|'
    FROM (SELECT count(*) AS cnt, w AS xyz FROM t1 GROUP BY 2)
   ORDER BY +cnt;
} {1 1 bbb | 2 2 aaa | 3 3 bbb |}

do_execsql_test 11.100 {
  DROP TABLE t1;
  DROP TABLE t2;
  CREATE TABLE t1(x);
  CREATE TABLE t2(y, z);
  SELECT ( SELECT y FROM t2 WHERE z = cnt )
    FROM ( SELECT count(*) AS cnt FROM t1 );
} {{}}

# 2019-05-29 ticket https://www.sqlite.org/src/info/c41afac34f15781f
# A LIMIT clause in a subquery is incorrectly applied to a subquery.
#
do_execsql_test 12.100 {
  DROP TABLE t1;
  DROP TABLE t2;
  CREATE TABLE t1(a);
  INSERT INTO t1 VALUES(1);
  INSERT INTO t1 VALUES(2);
  CREATE TABLE t2(b);
  INSERT INTO t2 VALUES(3);
  SELECT * FROM (
    SELECT * FROM (SELECT * FROM t1 LIMIT 1)
    UNION ALL
    SELECT * from t2);
} {1 3}

finish_test