SQLite

void sqlite3ValueApplyAffinity(
  sqlite3_value *pVal, 
  u8 affinity, 
  u8 enc
){
  applyAffinity((Mem *)pVal, affinity, enc);
}

/*
** Return the numeric type for pMem, either MEM_Int or MEM_Real or both or
** none.  
**
** Unlike applyNumericAffinity(), this routine does not modify pMem->flags.
** But it does set pMem->r and pMem->u.i appropriately.
*/
static u16 numericType(Mem *pMem){
  if( pMem->flags & (MEM_Int|MEM_Real) ){
    return pMem->flags & (MEM_Int|MEM_Real);
  }
  if( pMem->flags & (MEM_Str|MEM_Blob) ){
    if( sqlite3AtoF(pMem->z, &pMem->r, pMem->n, pMem->enc)==0 ){
      return 0;
    }
    if( sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc)==SQLITE_OK ){
      return MEM_Int;
    }
    return MEM_Real;
  }
  return 0;
}

#ifdef SQLITE_DEBUG
/*
** Write a nice string representation of the contents of cell pMem
** into buffer zBuf, length nBuf.
*/
void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf){

*/
case OP_Add:                   /* same as TK_PLUS, in1, in2, out3 */
case OP_Subtract:              /* same as TK_MINUS, in1, in2, out3 */
case OP_Multiply:              /* same as TK_STAR, in1, in2, out3 */
case OP_Divide:                /* same as TK_SLASH, in1, in2, out3 */
case OP_Remainder: {           /* same as TK_REM, in1, in2, out3 */
  char bIntint;   /* Started out as two integer operands */
  u16 flags;      /* Combined MEM_* flags from both inputs */
  u16 type1;      /* Numeric type of left operand */
  u16 type2;      /* Numeric type of right operand */
  i64 iA;         /* Integer value of left operand */
  i64 iB;         /* Integer value of right operand */
  double rA;      /* Real value of left operand */
  double rB;      /* Real value of right operand */

  pIn1 = &aMem[pOp->p1];
  type1 = numericType(pIn1);
  pIn2 = &aMem[pOp->p2];
  type2 = numericType(pIn2);
  pOut = &aMem[pOp->p3];
  flags = pIn1->flags | pIn2->flags;
  if( (flags & MEM_Null)!=0 ) goto arithmetic_result_is_null;
  if( (type1 & type2 & MEM_Int)!=0 ){
    iA = pIn1->u.i;
    iB = pIn2->u.i;
    bIntint = 1;
    switch( pOp->opcode ){
      case OP_Add:       if( sqlite3AddInt64(&iB,iA) ) goto fp_math;  break;
      case OP_Subtract:  if( sqlite3SubInt64(&iB,iA) ) goto fp_math;  break;
      case OP_Multiply:  if( sqlite3MulInt64(&iB,iA) ) goto fp_math;  break;

    MemSetTypeFlag(pOut, MEM_Int);
#else
    if( sqlite3IsNaN(rB) ){
      goto arithmetic_result_is_null;
    }
    pOut->r = rB;
    MemSetTypeFlag(pOut, MEM_Real);
    if( ((type1|type2)&MEM_Real)==0 && !bIntint ){
      sqlite3VdbeIntegerAffinity(pOut);
    }
#endif
  }
  break;

arithmetic_result_is_null:

# 2014-03-24
#
# 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.
#
#***********************************************************************
# 
# Tests to verify that arithmetic operators do not change the type of
# input operands.  Ticket [a8a0d2996a]
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix tkt-a8a0d2996a

do_execsql_test 1.0 {
  CREATE TABLE t(x,y);
  INSERT INTO t VALUES('1','1');
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x+0 AND y=='1';
} {text text}
do_execsql_test 1.1 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x-0 AND y=='1';
} {text text}
do_execsql_test 1.2 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x*1 AND y=='1';
} {text text}
do_execsql_test 1.3 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x/1 AND y=='1';
} {text text}
do_execsql_test 1.4 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x%4 AND y=='1';
} {text text}

do_execsql_test 2.0 {
  UPDATE t SET x='1xyzzy';
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x+0 AND y=='1';
} {text text}
do_execsql_test 2.1 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x-0 AND y=='1';
} {text text}
do_execsql_test 2.2 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x*1 AND y=='1';
} {text text}
do_execsql_test 2.3 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x/1 AND y=='1';
} {text text}
do_execsql_test 2.4 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x%4 AND y=='1';
} {text text}


do_execsql_test 3.0 {
  UPDATE t SET x='1.0';
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x+0 AND y=='1';
} {text text}
do_execsql_test 3.1 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x-0 AND y=='1';
} {text text}
do_execsql_test 3.2 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x*1 AND y=='1';
} {text text}
do_execsql_test 3.3 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x/1 AND y=='1';
} {text text}
do_execsql_test 3.4 {
  SELECT typeof(x), typeof(y) FROM t WHERE 1=x%4 AND y=='1';
} {text text}

do_execsql_test 4.0 {
  SELECT 1+1.;
} {2.0}
do_execsql_test 4.1 {
  SELECT '1.23e64'/'1.0000e+62';
} {123.0}
do_execsql_test 4.2 {
  SELECT '100x'+'-2y';
} {98}
do_execsql_test 4.3 {
  SELECT '100x'+'4.5y';
} {104.5}
do_execsql_test 4.4 {
  SELECT '-9223372036854775807x'-'1x';
} {-9.22337203685478e+18}
do_execsql_test 4.5 {
  SELECT '9223372036854775806x'+'1x';
} {9.22337203685478e+18}
do_execsql_test 4.6 {
  SELECT '1234x'/'10y';
} {123.4}