SQLite

  Parse *pParse,      /* Error messages will be written here */
  int iDb,            /* This is the database that must be used */
  const char *zType,  /* "view", "trigger", or "index" */
  const Token *pName  /* Name of the view, trigger, or index */
){
  sqlite3 *db;

  if( NEVER(iDb<0) ) return 0;
  db = pParse->db;
  assert( db->nDb>iDb );
  pFix->pParse = pParse;
  pFix->zDb = db->aDb[iDb].zName;
  pFix->pSchema = db->aDb[iDb].pSchema;
  pFix->zType = zType;
  pFix->pName = pName;
  pFix->bVarOnly = (iDb==1);
  return 1;
}

/*
** The following set of routines walk through the parse tree and assign
** a specific database to all table references where the database name
** was left unspecified in the original SQL statement.  The pFix structure

  int i;
  const char *zDb;
  struct SrcList_item *pItem;

  if( NEVER(pList==0) ) return 0;
  zDb = pFix->zDb;
  for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){
    if( pFix->bVarOnly==0 ){
      if( pItem->zDatabase && sqlite3StrICmp(pItem->zDatabase, zDb) ){
        sqlite3ErrorMsg(pFix->pParse,
            "%s %T cannot reference objects in database %s",
            pFix->zType, pFix->pName, pItem->zDatabase);
        return 1;
      }
      sqlite3DbFree(pFix->pParse->db, pItem->zDatabase);
      pItem->zDatabase = 0;
      pItem->pSchema = pFix->pSchema;
    }
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
    if( sqlite3FixSelect(pFix, pItem->pSelect) ) return 1;
    if( sqlite3FixExpr(pFix, pItem->pOn) ) return 1;
#endif
  }
  return 0;
}

      return 1;
    }
    if( sqlite3FixSrcList(pFix, pSelect->pSrc) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pSelect->pWhere) ){
      return 1;
    }
    if( sqlite3FixExprList(pFix, pSelect->pGroupBy) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pSelect->pHaving) ){
      return 1;
    }
    if( sqlite3FixExprList(pFix, pSelect->pOrderBy) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pSelect->pLimit) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pSelect->pOffset) ){
      return 1;
    }
    pSelect = pSelect->pPrior;
  }
  return 0;
}
int sqlite3FixExpr(
  DbFixer *pFix,     /* Context of the fixation */
  Expr *pExpr        /* The expression to be fixed to one database */
){
  while( pExpr ){
    if( pExpr->op==TK_VARIABLE ){
      if( pFix->pParse->db->init.busy ){
        pExpr->op = TK_NULL;
      }else{
        sqlite3ErrorMsg(pFix->pParse, "%s cannot use variables", pFix->zType);
        return 1;
      }
    }
    if( ExprHasProperty(pExpr, EP_TokenOnly) ) break;
    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
      if( sqlite3FixSelect(pFix, pExpr->x.pSelect) ) return 1;
    }else{
      if( sqlite3FixExprList(pFix, pExpr->x.pList) ) return 1;
    }
    if( sqlite3FixExpr(pFix, pExpr->pRight) ){

** routines as they walk the parse tree to make database references
** explicit.  
*/
typedef struct DbFixer DbFixer;
struct DbFixer {
  Parse *pParse;      /* The parsing context.  Error messages written here */
  Schema *pSchema;    /* Fix items to this schema */
  int bVarOnly;       /* Check for variable references only */
  const char *zDb;    /* Make sure all objects are contained in this database */
  const char *zType;  /* Type of the container - used for error messages */
  const Token *pName; /* Name of the container - used for error messages */
};

/*
** An objected used to accumulate the text of a string where we

  pTrig->step_list = pStepList;
  while( pStepList ){
    pStepList->pTrig = pTrig;
    pStepList = pStepList->pNext;
  }
  nameToken.z = pTrig->zName;
  nameToken.n = sqlite3Strlen30(nameToken.z);
  if( sqlite3FixInit(&sFix, pParse, iDb, "trigger", &nameToken) && (
      sqlite3FixTriggerStep(&sFix, pTrig->step_list) 
   || sqlite3FixExpr(&sFix, pTrig->pWhen) 
  )){
    goto triggerfinish_cleanup;
  }

  /* if we are not initializing,
  ** build the sqlite_master entry
  */
  if( !db->init.busy ){

# 2009 December 29
#
# 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 tests the effects of SQL variable references embedded in
# triggers. If the user attempts to create such a trigger, it is an
# error. However, if an existing trigger definition is read from
# the sqlite_master table, the variable reference always evaluates
# to NULL.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
ifcapable {!trigger} {
  finish_test
  return
}
set testprefix triggerE

do_execsql_test 1.0 {
  CREATE TABLE t1(a, b);
  CREATE TABLE t2(c, d);
  CREATE TABLE t3(e, f);
}

# forcedelete test.db2
# do_execsql_test 1.1 {
#   ATTACH 'test.db2' AS aux;
#   CREATE TABLE aux.t4(x);
#   INSERT INTO aux.t4 VALUES(5);
# 
#   CREATE TRIGGER tr1 AFTER INSERT ON t1 WHEN new.a IN (SELECT x FROM aux.t4)
#   BEGIN
#     SELECT 1;
#   END;
# } 
# do_execsql_test 1.2 { INSERT INTO t1 VALUES(1,1); }
# do_execsql_test 1.3 { INSERT INTO t1 VALUES(5,5); }

#-------------------------------------------------------------------------
# Attempt to create various triggers that use bound variables.
#
set errmsg "trigger cannot use variables"
foreach {tn defn} {
  1 { AFTER INSERT ON t1 WHEN new.a = ? BEGIN SELECT 1; END; }
  2 { BEFORE DELETE ON t1 BEGIN SELECT ?; END; }
  3 { BEFORE DELETE ON t1 BEGIN SELECT * FROM (SELECT * FROM (SELECT ?)); END; }
  5 { BEFORE DELETE ON t1 BEGIN SELECT * FROM t2 GROUP BY ?; END; }
  6 { BEFORE DELETE ON t1 BEGIN SELECT * FROM t2 LIMIT ?; END; }
  7 { BEFORE DELETE ON t1 BEGIN SELECT * FROM t2 ORDER BY ?; END; }
  8 { BEFORE UPDATE ON t1 BEGIN UPDATE t2 SET c = ?; END; }
  9 { BEFORE UPDATE ON t1 BEGIN UPDATE t2 SET c = 1 WHERE d = ?; END; }
} {
  catchsql {drop trigger tr1}
  do_catchsql_test 1.1.$tn "CREATE TRIGGER tr1 $defn" [list 1 $errmsg]
  do_catchsql_test 1.2.$tn "CREATE TEMP TRIGGER tr1 $defn" [list 1 $errmsg]
}

#-------------------------------------------------------------------------
# Test that variable references within trigger definitions loaded from 
# the sqlite_master table are automatically converted to NULL.
#
do_execsql_test 2.1 {
  PRAGMA writable_schema = 1;
  INSERT INTO sqlite_master VALUES('trigger', 'tr1', 't1', 0,
    'CREATE TRIGGER tr1 AFTER INSERT ON t1 BEGIN 
        INSERT INTO t2 VALUES(?1, ?2); 
     END'
  );

  INSERT INTO sqlite_master VALUES('trigger', 'tr2', 't3', 0,
    'CREATE TRIGGER tr2 AFTER INSERT ON t3 WHEN ?1 IS NULL BEGIN
        UPDATE t2 SET c=d WHERE c IS ?2;
     END'
  );
}
db close
sqlite3 db test.db

do_execsql_test 2.2.1 {
  INSERT INTO t1 VALUES(1, 2);
  SELECT * FROM t2;
} {{} {}}
do_test 2.2.2 {
  set one 3
  execsql {
    DELETE FROM t2;
    INSERT INTO t1 VALUES($one, ?1);
    SELECT * FROM t2;
  }
} {{} {}}
do_execsql_test 2.2.3 { SELECT * FROM t1 } {1 2 3 3}

do_execsql_test 2.3 {
  DELETE FROM t2;
  INSERT INTO t2 VALUES('x', 'y');
  INSERT INTO t2 VALUES(NULL, 'z');
  INSERT INTO t3 VALUES(1, 2);
  SELECT * FROM t3;
  SELECT * FROM t2;
} {1 2 x y z z}

finish_test