SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.503 2009/02/24 18:33:15 danielk1977 Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.

*/
static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){
  Table *pTab;
  Expr *pExpr;

  assert( !p->pGroupBy );

  if( p->pWhere || p->pEList->nExpr!=1 
   || p->pSrc->nSrc!=1 || p->pSrc->a[0].pSelect
  ){
    return 0;
  }

  pTab = p->pSrc->a[0].pTab;
  pExpr = p->pEList->a[0].pExpr;

        if( !pMinMax && flag ){
          sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);
          VdbeComment((v, "%s() by index",
                (flag==WHERE_ORDERBY_MIN?"min":"max")));
        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, &sAggInfo);
      }

      pOrderBy = 0;
      if( pHaving ){
        sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
      }


      selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, -1, 
                      pDest, addrEnd, addrEnd);
      sqlite3ExprListDelete(db, pDel);
    }
    sqlite3VdbeResolveLabel(v, addrEnd);
    
  } /* endif aggregate query */

# 2009 February 24
#
# 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 count(*)" statements.
#
# $Id: count.test,v 1.2 2009/02/24 18:33:15 danielk1977 Exp $

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

# Test plan:
#
#  count-1.*: Test that the OP_Count instruction appears to work on both
#             tables and indexes. Test both when they contain 0 entries,
#             when all entries are on the root page, and when the b-tree
#             forms a structure 2 and 3 levels deep.
#            
#  count-2.*: Test that 
#
#

set iTest 0
foreach zIndex [list {
  /* no-op */
} {
  CREATE INDEX i1 ON t1(a);
}] { 
  incr iTest
  do_test count-1.$iTest.1 {
    execsql {
      DROP TABLE IF EXISTS t1;
      CREATE TABLE t1(a, b);
    }
    execsql $zIndex
    execsql { SELECT count(*) FROM t1 }
  } {0}
  
  do_test count-1.$iTest.2 {
    execsql {
      INSERT INTO t1 VALUES(1, 2);
      INSERT INTO t1 VALUES(3, 4);
      SELECT count(*) FROM t1;
    }
  } {2}

  do_test count-1.$iTest.3 {
    execsql {
      INSERT INTO t1 SELECT * FROM t1;          --   4
      INSERT INTO t1 SELECT * FROM t1;          --   8
      INSERT INTO t1 SELECT * FROM t1;          --  16
      INSERT INTO t1 SELECT * FROM t1;          --  32
      INSERT INTO t1 SELECT * FROM t1;          --  64
      INSERT INTO t1 SELECT * FROM t1;          -- 128
      INSERT INTO t1 SELECT * FROM t1;          -- 256
      SELECT count(*) FROM t1;
    }
  } {256}
  
  do_test count-1.$iTest.4 {
    execsql {
      INSERT INTO t1 SELECT * FROM t1;          --  512
      INSERT INTO t1 SELECT * FROM t1;          -- 1024
      INSERT INTO t1 SELECT * FROM t1;          -- 2048
      INSERT INTO t1 SELECT * FROM t1;          -- 4096
      SELECT count(*) FROM t1;
    }
  } {4096}
  
  do_test count-1.$iTest.5 {
    execsql {
      BEGIN;
      INSERT INTO t1 SELECT * FROM t1;          --  8192
      INSERT INTO t1 SELECT * FROM t1;          -- 16384
      INSERT INTO t1 SELECT * FROM t1;          -- 32768
      INSERT INTO t1 SELECT * FROM t1;          -- 65536
      COMMIT;
      SELECT count(*) FROM t1;
    }
  } {65536}
}

proc uses_op_count {sql} {
  if {[lsearch [execsql "EXPLAIN $sql"] Count]>=0} {
    return 1;
  }
  return 0
}

do_test count-2.1 {
  execsql {
    CREATE TABLE t2(a, b);
  }
  uses_op_count {SELECT count(*) FROM t2}
} {1}
do_test count-2.2 {
  catchsql {SELECT count(DISTINCT *) FROM t2}
} {1 {near "*": syntax error}}
do_test count-2.3 {
  uses_op_count {SELECT count(DISTINCT a) FROM t2}
} {0}
do_test count-2.4 {
  uses_op_count {SELECT count(a) FROM t2}
} {0}
do_test count-2.5 {
  uses_op_count {SELECT count() FROM t2}
} {1}
do_test count-2.6 {
  catchsql {SELECT count(DISTINCT) FROM t2}
} {1 {DISTINCT aggregates must have exactly one argument}}
do_test count-2.7 {
  uses_op_count {SELECT count(*)+1 FROM t2}
} {0}
do_test count-2.8 {
  uses_op_count {SELECT count(*) FROM t2 WHERE a IS NOT NULL}
} {0}
do_test count-2.9 {
  catchsql {SELECT count(*) FROM t2 HAVING count(*)>1}
} {1 {a GROUP BY clause is required before HAVING}}
do_test count-2.10 {
  uses_op_count {SELECT count(*) FROM (SELECT 1)}
} {0}
do_test count-2.11 {
  execsql { CREATE VIEW v1 AS SELECT 1 AS a }
  uses_op_count {SELECT count(*) FROM v1}
} {0}
do_test count-2.12 {
  uses_op_count {SELECT count(*), max(a) FROM t2}
} {0}
do_test count-2.13 {
  uses_op_count {SELECT count(*) FROM t1, t2}
} {0}

do_test count-3.1 {
  execsql {
    CREATE TABLE t3(a, b);
    SELECT a FROM (SELECT count(*) AS a FROM t3) WHERE a==0;
  }
} {0}
do_test count-3.2 {
  execsql {
    SELECT a FROM (SELECT count(*) AS a FROM t3) WHERE a==1;
  }
} {}

finish_test