SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.61 2002/05/21 13:43:04 drh Exp $
*/
#include "sqliteInt.h"


/*
** Construct a new expression node and return a pointer to it.  Memory
** for this node is obtained from sqliteMalloc().  The calling function

  sqliteFree(pList->a);
  sqliteFree(pList);
}

/*
** Walk an expression tree.  Return 1 if the expression is constant
** and 0 if it involves variables.
**
** For the purposes of this function, a double-quoted string (ex: "abc")
** is considered a variable but a single-quoted string (ex: 'abc') is
** a constant.
*/
int sqliteExprIsConstant(Expr *p){
  switch( p->op ){
    case TK_ID:
    case TK_COLUMN:
    case TK_DOT:
      return 0;
    case TK_STRING:
      return p->token.z[0]=='\'';
    case TK_INTEGER:
    case TK_FLOAT:
      return 1;
    default: {
      if( p->pLeft && !sqliteExprIsConstant(p->pLeft) ) return 0;
      if( p->pRight && !sqliteExprIsConstant(p->pRight) ) return 0;
      if( p->pList ){
        int i;
        for(i=0; i<p->pList->nExpr; i++){

  IdList *pTabList,  /* List of tables used to resolve column names */
  ExprList *pEList,  /* List of expressions used to resolve "AS" */
  Expr *pExpr        /* The expression to be analyzed. */
){
  if( pExpr==0 || pTabList==0 ) return 0;
  assert( base+pTabList->nId<=pParse->nTab );
  switch( pExpr->op ){
    /* Double-quoted strings (ex: "abc") are used as identifiers if
    ** possible.  Otherwise they remain as strings.  Single-quoted
    ** strings (ex: 'abc') are always string literals.
    */
    case TK_STRING: {
      if( pExpr->token.z[0]=='\'' ) break;
      /* Fall thru into the TK_ID case if this is a double-quoted string */
    }
    /* A lone identifier.  Try and match it as follows:
    **
    **     1.  To the name of a column of one of the tables in pTabList
    **
    **     2.  To the right side of an AS keyword in the column list of
    **         a SELECT statement.  (For example, match against 'x' in
    **         "SELECT a+b AS 'x' FROM t1".)

      if( cnt==0 && sqliteIsRowid(z) ){
        pExpr->iColumn = -1;
        pExpr->iTable = base;
        cnt = 1 + (pTabList->nId>1);
        pExpr->op = TK_COLUMN;
      }
      sqliteFree(z);
      if( cnt==0 && pExpr->token.z[0]!='"' ){
        sqliteSetNString(&pParse->zErrMsg, "no such column: ", -1,  
          pExpr->token.z, pExpr->token.n, 0);
        pParse->nErr++;
        return 1;
      }else if( cnt>1 ){
        sqliteSetNString(&pParse->zErrMsg, "ambiguous column name: ", -1,  
          pExpr->token.z, pExpr->token.n, 0);

#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is the ability to specify table and column names
# as quoted strings.
#
# $Id: quote.test,v 1.3 2002/05/21 13:43:04 drh Exp $

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

# Create a table with a strange name and with strange column names.
#
do_test quote-1.0 {

} {0 {}}
do_test quote-1.2 {
  set r [catch {
    execsql {SELECT * FROM '@abc'}
  } msg ]
  lappend r $msg
} {0 {5 hello}}
do_test quote-1.3 {
  set r [catch {
    execsql {SELECT '@abc'.'!pqr', '@abc'.'#xyz'+5 FROM '@abc'}
  } msg ]
  lappend r $msg
} {0 {hello 10}}
do_test quote-1.3.1 {
  catchsql {
    SELECT '!pqr', '#xyz'+5 FROM '@abc'
  }
} {0 {!pqr 5}}
do_test quote-1.3.2 {
  catchsql {
    SELECT "!pqr", "#xyz"+5 FROM '@abc'
  }
} {0 {hello 10}}
do_test quote-1.3 {
  set r [catch {
    execsql {SELECT '@abc'.'!pqr', '@abc'.'#xyz'+5 FROM '@abc'}
  } msg ]
  lappend r $msg
} {0 {hello 10}}
do_test quote-1.4 {