build.c

sqlite数据库管理系统开放源码

/*
** 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 contains C code routines that are called by the SQLite parser
** when syntax rules are reduced.  The routines in this file handle the
** following kinds of SQL syntax:
**
**     CREATE TABLE
**     DROP TABLE
**     CREATE INDEX
**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.176.2.3 2004/08/28 14:53:34 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Check to see if the schema for the database needs
** to be read from the SQLITE_MASTER and SQLITE_TEMP_MASTER tables.
** If it does, then read it.
*/
void sqliteBeginParse(Parse *pParse, int explainFlag){
  sqlite *db = pParse->db;
  int i;
  pParse->explain = explainFlag;
  if((db->flags & SQLITE_Initialized)==0 && db->init.busy==0 ){
    int rc = sqliteInit(db, &pParse->zErrMsg);
    if( rc!=SQLITE_OK ){
      pParse->rc = rc;
      pParse->nErr++;
    }
  }
  for(i=0; i<db->nDb; i++){
    DbClearProperty(db, i, DB_Locked);
    if( !db->aDb[i].inTrans ){
      DbClearProperty(db, i, DB_Cookie);
    }
  }
  pParse->nVar = 0;
}

/*
** This routine is called after a single SQL statement has been
** parsed and we want to execute the VDBE code to implement 
** that statement.  Prior action routines should have already
** constructed VDBE code to do the work of the SQL statement.
** This routine just has to execute the VDBE code.
**
** Note that if an error occurred, it might be the case that
** no VDBE code was generated.
*/
void sqliteExec(Parse *pParse){
  sqlite *db = pParse->db;
  Vdbe *v = pParse->pVdbe;

  if( v==0 && (v = sqliteGetVdbe(pParse))!=0 ){
    sqliteVdbeAddOp(v, OP_Halt, 0, 0);
  }
  if( sqlite_malloc_failed ) return;
  if( v && pParse->nErr==0 ){
    FILE *trace = (db->flags & SQLITE_VdbeTrace)!=0 ? stdout : 0;
    sqliteVdbeTrace(v, trace);
    sqliteVdbeMakeReady(v, pParse->nVar, pParse->explain);
    pParse->rc = pParse->nErr ? SQLITE_ERROR : SQLITE_DONE;
    pParse->colNamesSet = 0;
  }else if( pParse->rc==SQLITE_OK ){
    pParse->rc = SQLITE_ERROR;
  }
  pParse->nTab = 0;
  pParse->nMem = 0;
  pParse->nSet = 0;
  pParse->nAgg = 0;
  pParse->nVar = 0;
}

/*
** Locate the in-memory structure that describes 
** a particular database table given the name
** of that table and (optionally) the name of the database
** containing the table.  Return NULL if not found.
**
** If zDatabase is 0, all databases are searched for the
** table and the first matching table is returned.  (No checking
** for duplicate table names is done.)  The search order is
** TEMP first, then MAIN, then any auxiliary databases added
** using the ATTACH command.
**
** See also sqliteLocateTable().
*/
Table *sqliteFindTable(sqlite *db, const char *zName, const char *zDatabase){
  Table *p = 0;
  int i;
  for(i=0; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;   /* Search TEMP before MAIN */
    if( zDatabase!=0 && sqliteStrICmp(zDatabase, db->aDb[j].zName) ) continue;
    p = sqliteHashFind(&db->aDb[j].tblHash, zName, strlen(zName)+1);
    if( p ) break;
  }
  return p;
}

/*
** Locate the in-memory structure that describes 
** a particular database table given the name
** of that table and (optionally) the name of the database
** containing the table.  Return NULL if not found.
** Also leave an error message in pParse->zErrMsg.
**
** The difference between this routine and sqliteFindTable()
** is that this routine leaves an error message in pParse->zErrMsg
** where sqliteFindTable() does not.
*/
Table *sqliteLocateTable(Parse *pParse, const char *zName, const char *zDbase){
  Table *p;

  p = sqliteFindTable(pParse->db, zName, zDbase);
  if( p==0 ){
    if( zDbase ){
      sqliteErrorMsg(pParse, "no such table: %s.%s", zDbase, zName);
    }else if( sqliteFindTable(pParse->db, zName, 0)!=0 ){
      sqliteErrorMsg(pParse, "table \"%s\" is not in database \"%s\"",
         zName, zDbase);
    }else{
      sqliteErrorMsg(pParse, "no such table: %s", zName);
    }
  }
  return p;
}

/*
** Locate the in-memory structure that describes 
** a particular index given the name of that index
** and the name of the database that contains the index.
** Return NULL if not found.
**
** If zDatabase is 0, all databases are searched for the
** table and the first matching index is returned.  (No checking
** for duplicate index names is done.)  The search order is
** TEMP first, then MAIN, then any auxiliary databases added
** using the ATTACH command.
*/
Index *sqliteFindIndex(sqlite *db, const char *zName, const char *zDb){
  Index *p = 0;
  int i;
  for(i=0; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
    if( zDb && sqliteStrICmp(zDb, db->aDb[j].zName) ) continue;
    p = sqliteHashFind(&db->aDb[j].idxHash, zName, strlen(zName)+1);
    if( p ) break;
  }
  return p;
}

/*
** Remove the given index from the index hash table, and free
** its memory structures.
**
** The index is removed from the database hash tables but
** it is not unlinked from the Table that it indexes.
** Unlinking from the Table must be done by the calling function.
*/
static void sqliteDeleteIndex(sqlite *db, Index *p){
  Index *pOld;

  assert( db!=0 && p->zName!=0 );
  pOld = sqliteHashInsert(&db->aDb[p->iDb].idxHash, p->zName,
                          strlen(p->zName)+1, 0);
  if( pOld!=0 && pOld!=p ){
    sqliteHashInsert(&db->aDb[p->iDb].idxHash, pOld->zName,
                     strlen(pOld->zName)+1, pOld);
  }
  sqliteFree(p);
}

/*
** Unlink the given index from its table, then remove
** the index from the index hash table and free its memory
** structures.
*/
void sqliteUnlinkAndDeleteIndex(sqlite *db, Index *pIndex){
  if( pIndex->pTable->pIndex==pIndex ){
    pIndex->pTable->pIndex = pIndex->pNext;
  }else{
    Index *p;
    for(p=pIndex->pTable->pIndex; p && p->pNext!=pIndex; p=p->pNext){}
    if( p && p->pNext==pIndex ){
      p->pNext = pIndex->pNext;
    }
  }
  sqliteDeleteIndex(db, pIndex);
}

/*
** Erase all schema information from the in-memory hash tables of
** database connection.  This routine is called to reclaim memory
** before the connection closes.  It is also called during a rollback
** if there were schema changes during the transaction.
**
** If iDb<=0 then reset the internal schema tables for all database
** files.  If iDb>=2 then reset the internal schema for only the
** single file indicated.
*/
void sqliteResetInternalSchema(sqlite *db, int iDb){
  HashElem *pElem;
  Hash temp1;
  Hash temp2;
  int i, j;

  assert( iDb>=0 && iDb<db->nDb );
  db->flags &= ~SQLITE_Initialized;
  for(i=iDb; i<db->nDb; i++){
    Db *pDb = &db->aDb[i];
    temp1 = pDb->tblHash;
    temp2 = pDb->trigHash;
    sqliteHashInit(&pDb->trigHash, SQLITE_HASH_STRING, 0);
    sqliteHashClear(&pDb->aFKey);
    sqliteHashClear(&pDb->idxHash);
    for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){
      Trigger *pTrigger = sqliteHashData(pElem);
      sqliteDeleteTrigger(pTrigger);
    }
    sqliteHashClear(&temp2);
    sqliteHashInit(&pDb->tblHash, SQLITE_HASH_STRING, 0);
    for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
      Table *pTab = sqliteHashData(pElem);
      sqliteDeleteTable(db, pTab);
    }
    sqliteHashClear(&temp1);
    DbClearProperty(db, i, DB_SchemaLoaded);
    if( iDb>0 ) return;
  }
  assert( iDb==0 );
  db->flags &= ~SQLITE_InternChanges;

  /* If one or more of the auxiliary database files has been closed,
  ** then remove then from the auxiliary database list.  We take the
  ** opportunity to do this here since we have just deleted all of the
  ** schema hash tables and therefore do not have to make any changes
  ** to any of those tables.
  */
  for(i=0; i<db->nDb; i++){
    struct Db *pDb = &db->aDb[i];
    if( pDb->pBt==0 ){
      if( pDb->pAux && pDb->xFreeAux ) pDb->xFreeAux(pDb->pAux);
      pDb->pAux = 0;
    }
  }
  for(i=j=2; i<db->nDb; i++){
    struct Db *pDb = &db->aDb[i];
    if( pDb->pBt==0 ){
      sqliteFree(pDb->zName);
      pDb->zName = 0;
      continue;
    }
    if( j<i ){
      db->aDb[j] = db->aDb[i];
    }
    j++;
  }
  memset(&db->aDb[j], 0, (db->nDb-j)*sizeof(db->aDb[j]));
  db->nDb = j;
  if( db->nDb<=2 && db->aDb!=db->aDbStatic ){
    memcpy(db->aDbStatic, db->aDb, 2*sizeof(db->aDb[0]));
    sqliteFree(db->aDb);
    db->aDb = db->aDbStatic;
  }
}

/*
** This routine is called whenever a rollback occurs.  If there were
** schema changes during the transaction, then we have to reset the
** internal hash tables and reload them from disk.
*/
void sqliteRollbackInternalChanges(sqlite *db){
  if( db->flags & SQLITE_InternChanges ){
    sqliteResetInternalSchema(db, 0);
  }
}

/*
** This routine is called when a commit occurs.
*/
void sqliteCommitInternalChanges(sqlite *db){
  db->aDb[0].schema_cookie = db->next_cookie;
  db->flags &= ~SQLITE_InternChanges;
}

/*
** Remove the memory data structures associated with the given
** Table.  No changes are made to disk by this routine.
**
** This routine just deletes the data structure.  It does not unlink
** the table data structure from the hash table.  Nor does it remove
** foreign keys from the sqlite.aFKey hash table.  But it does destroy
** memory structures of the indices and foreign keys associated with 
** the table.
**
** Indices associated with the table are unlinked from the "db"
** data structure if db!=NULL.  If db==NULL, indices attached to
** the table are deleted, but it is assumed they have already been
** unlinked.
*/
void sqliteDeleteTable(sqlite *db, Table *pTable){
  int i;
  Index *pIndex, *pNext;
  FKey *pFKey, *pNextFKey;

  if( pTable==0 ) return;

  /* Delete all indices associated with this table
  */
  for(pIndex = pTable->pIndex; pIndex; pIndex=pNext){
    pNext = pIndex->pNext;
    assert( pIndex->iDb==pTable->iDb || (pTable->iDb==0 && pIndex->iDb==1) );
    sqliteDeleteIndex(db, pIndex);
  }

  /* Delete all foreign keys associated with this table.  The keys
  ** should have already been unlinked from the db->aFKey hash table 
  */
  for(pFKey=pTable->pFKey; pFKey; pFKey=pNextFKey){
    pNextFKey = pFKey->pNextFrom;
    assert( pTable->iDb<db->nDb );
    assert( sqliteHashFind(&db->aDb[pTable->iDb].aFKey,
                           pFKey->zTo, strlen(pFKey->zTo)+1)!=pFKey );
    sqliteFree(pFKey);
  }

  /* Delete the Table structure itself.
  */
  for(i=0; i<pTable->nCol; i++){
    sqliteFree(pTable->aCol[i].zName);
    sqliteFree(pTable->aCol[i].zDflt);
    sqliteFree(pTable->aCol[i].zType);
  }
  sqliteFree(pTable->zName);
  sqliteFree(pTable->aCol);
  sqliteSelectDelete(pTable->pSelect);
  sqliteFree(pTable);
}

/*
** Unlink the given table from the hash tables and the delete the
** table structure with all its indices and foreign keys.
*/
static void sqliteUnlinkAndDeleteTable(sqlite *db, Table *p){
  Table *pOld;
  FKey *pF1, *pF2;
  int i = p->iDb;
  assert( db!=0 );
  pOld = sqliteHashInsert(&db->aDb[i].tblHash, p->zName, strlen(p->zName)+1, 0);
  assert( pOld==0 || pOld==p );
  for(pF1=p->pFKey; pF1; pF1=pF1->pNextFrom){
    int nTo = strlen(pF1->zTo) + 1;
    pF2 = sqliteHashFind(&db->aDb[i].aFKey, pF1->zTo, nTo);
    if( pF2==pF1 ){
      sqliteHashInsert(&db->aDb[i].aFKey, pF1->zTo, nTo, pF1->pNextTo);
    }else{
      while( pF2 && pF2->pNextTo!=pF1 ){ pF2=pF2->pNextTo; }
      if( pF2 ){
        pF2->pNextTo = pF1->pNextTo;
      }
    }
  }
  sqliteDeleteTable(db, p);
}

/*
** Construct the name of a user table or index from a token.
**
** Space to hold the name is obtained from sqliteMalloc() and must
** be freed by the calling function.
*/
char *sqliteTableNameFromToken(Token *pName){
  char *zName = sqliteStrNDup(pName->z, pName->n);
  sqliteDequote(zName);
  return zName;
}

/*
** Generate code to open the appropriate master table.  The table
** opened will be SQLITE_MASTER for persistent tables and 
** SQLITE_TEMP_MASTER for temporary tables.  The table is opened
** on cursor 0.
*/
void sqliteOpenMasterTable(Vdbe *v, int isTemp){
  sqliteVdbeAddOp(v, OP_Integer, isTemp, 0);
  sqliteVdbeAddOp(v, OP_OpenWrite, 0, 2);
}

/*
** Begin constructing a new table representation in memory.  This is
** the first of several action routines that get called in response
** to a CREATE TABLE statement.  In particular, this routine is called
** after seeing tokens "CREATE" and "TABLE" and the table name.  The
** pStart token is the CREATE and pName is the table name.  The isTemp
** flag is true if the table should be stored in the auxiliary database
** file instead of in the main database file.  This is normally the case
** when the "TEMP" or "TEMPORARY" keyword occurs in between
** CREATE and TABLE.
**
** The new table record is initialized and put in pParse->pNewTable.
** As more of the CREATE TABLE statement is parsed, additional action
** routines will be called to add more information to this record.
** At the end of the CREATE TABLE statement, the sqliteEndTable() routine
** is called to complete the construction of the new table record.
*/
void sqliteStartTable(