SQLite

#ifdef SQLITE_ENABLE_SESSION

#include "sqlite3session.h"
#include <assert.h>
#include <string.h>

#include "sqliteInt.h"
#include "vdbeInt.h"


typedef struct SessionTable SessionTable;
typedef struct SessionChange SessionChange;
typedef struct SessionBuffer SessionBuffer;

/*
** Session handle structure.
*/

** a subset of the initial values that the modified row contained at the
** start of the session. Or no initial values if the row was inserted.
*/
struct SessionTable {
  SessionTable *pNext;
  char *zName;                    /* Local name of table */
  int nCol;                       /* Number of columns in table zName */
  const char **azCol;             /* Column names */
  u8 *abPK;                       /* Array of primary key flags */
  int nEntry;                     /* Total number of entries in hash table */
  int nChange;                    /* Size of apChange[] array */
  SessionChange **apChange;       /* Hash table buckets */
};

/* 
** RECORD FORMAT:

*/

/*
** For each row modified during a session, there exists a single instance of
** this structure stored in a SessionTable.aChange[] hash table.
*/
struct SessionChange {
  int bInsert;                    /* True if row was inserted this session */
  int nRecord;                    /* Number of bytes in buffer aRecord[] */
  u8 *aRecord;                    /* Buffer containing old.* record */
  SessionChange *pNext;           /* For hash-table collisions */
};

/*
** Instances of this structure are used to build strings or binary records.

      break;
    }
  }

  *pnWrite += nByte;
  return SQLITE_OK;
}

#define HASH_APPEND(hash, add) ((hash) << 3) ^ (hash) ^ (int)(add)
static int sessionHashAppendI64(int h, i64 i){
  h = HASH_APPEND(h, i & 0xFFFFFFFF);
  return HASH_APPEND(h, (i>>32)&0xFFFFFFFF);
}
static int sessionHashAppendBlob(int h, int n, const u8 *z){
  int i;
  for(i=0; i<n; i++) h = HASH_APPEND(h, z[i]);
  return h;
}

/*

** This function calculates a hash based on the primary key values of
** the old.* or new.* row currently available.
*/
static int sessionPreupdateHash(
  sqlite3 *db,                    /* Database handle */
  SessionTable *pTab,             /* Session table handle */
  int bNew,                       /* True to hash the new.* PK */
  int *piHash                     /* OUT: Hash value */
){
  int h = 0;
  int i;

  assert( pTab->nCol==sqlite3_preupdate_count(db) );
  for(i=0; i<pTab->nCol; i++){
    if( pTab->abPK[i] ){
      int rc;
      int eType;
      sqlite3_value *pVal;

      if( bNew ){
        rc = sqlite3_preupdate_new(db, i, &pVal);
      }else{
        rc = sqlite3_preupdate_old(db, i, &pVal);
      }

      eType = sqlite3_value_type(pVal);
      h = HASH_APPEND(h, eType);
      switch( eType ){
        case SQLITE_INTEGER: 
        case SQLITE_FLOAT: {
          i64 iVal;
          if( eType==SQLITE_INTEGER ){
            iVal = sqlite3_value_int64(pVal);
          }else{
            double rVal = sqlite3_value_double(pVal);
            assert( sizeof(iVal)==8 && sizeof(rVal)==8 );
            memcpy(&iVal, &rVal, 8);
          }
          h = sessionHashAppendI64(h, iVal);
          break;
        }

        case SQLITE_TEXT: 
        case SQLITE_BLOB: {
          int n = sqlite3_value_bytes(pVal);
          const u8 *z = eType==SQLITE_TEXT ?
            sqlite3_value_text(pVal) : sqlite3_value_blob(pVal);
          h = sessionHashAppendBlob(h, n, z);
          break;
        }
      }
    }
  }

  *piHash = (h % pTab->nChange);
  return SQLITE_OK;
}

static int sessionChangeHash(
  sqlite3 *db,
  SessionTable *pTab,
  SessionChange *pChange,
  int nBucket
){
  int h = 0;
  int i;
  u8 *a = pChange->aRecord;

  for(i=0; i<pTab->nCol; i++){
    int eType = *a++;
    int isPK = pTab->abPK[i];

    if( isPK ) h = HASH_APPEND(h, eType);
    switch( eType ){
      case SQLITE_INTEGER:
      case SQLITE_FLOAT: {
        if( isPK ){
          i64 iVal = sessionGetI64(a);
          h = sessionHashAppendI64(h, iVal);
        }
        a += 8;
        break;
      }
      case SQLITE_TEXT:
      case SQLITE_BLOB: {
        int n;
        a += sessionVarintGet(a, &n);
        if( isPK ){
          h = sessionHashAppendBlob(h, n, a);
        }
        a += n;
        break;
      }
    }
  }
  return (h % nBucket);
}

static int sessionPreupdateEqual(
  sqlite3 *db,
  SessionTable *pTab,
  SessionChange *pChange,
  int bNew,
  int *pbEqual
){
  int i;
  u8 *a = pChange->aRecord;

  *pbEqual = 0;

  for(i=0; i<pTab->nCol; i++){
    int eType = *a++;
    if( !pTab->abPK[i] ){
      switch( eType ){
        case SQLITE_INTEGER: 
        case SQLITE_FLOAT:
          a += 8;
          break;

        case SQLITE_TEXT: 
        case SQLITE_BLOB: {
          int n;
          a += sessionVarintGet(a, &n);
          a += n;
          break;
        }
      }
    }else{
      sqlite3_value *pVal;
      int rc;
      if( bNew ){
        rc = sqlite3_preupdate_new(db, i, &pVal);
      }else{
        rc = sqlite3_preupdate_old(db, i, &pVal);
      }
      if( rc!=SQLITE_OK || sqlite3_value_type(pVal)!=eType ) return rc;

      switch( eType ){
        case SQLITE_INTEGER:
        case SQLITE_FLOAT: {
          i64 iVal = sessionGetI64(a);
          a += 8;
          if( eType==SQLITE_INTEGER ){
            if( sqlite3_value_int64(pVal)!=iVal ) return SQLITE_OK;
          }else{
            double rVal;
            assert( sizeof(iVal)==8 && sizeof(rVal)==8 );
            memcpy(&rVal, &iVal, 8);
            if( sqlite3_value_double(pVal)!=rVal ) return SQLITE_OK;
          }
          break;
        }
        case SQLITE_TEXT:
        case SQLITE_BLOB: {
          int n;
          const u8 *z;
          a += sessionVarintGet(a, &n);
          if( sqlite3_value_bytes(pVal)!=n ) return SQLITE_OK;
          z = eType==SQLITE_TEXT ? 
            sqlite3_value_text(pVal) : sqlite3_value_blob(pVal);
          if( memcmp(a, z, n) ) return SQLITE_OK;
          a += n;
          break;
        }
      }
    }
  }

  *pbEqual = 1;
  return SQLITE_OK;
}

/*
** If required, grow the hash table used to store changes on table pTab 
** (part of the session pSession). If a fatal OOM error occurs, set the
** session object to failed and return SQLITE_ERROR. Otherwise, return
** SQLITE_OK.

    }
    memset(apNew, 0, sizeof(SessionChange *) * nNew);

    for(i=0; i<pTab->nChange; i++){
      SessionChange *p;
      SessionChange *pNext;
      for(p=pTab->apChange[i]; p; p=pNext){
        int iHash = sessionChangeHash(pSession->db, pTab, p, nNew);
        pNext = p->pNext;
        p->pNext = apNew[iHash];
        apNew[iHash] = p;
      }
    }

    sqlite3_free(pTab->apChange);
    pTab->nChange = nNew;
    pTab->apChange = apNew;
  }

  return SQLITE_OK;
}

/*
** This function queries the database for the names of the columns of table
** zThis, in schema zDb. It is expected that the table has nCol columns. If
** not, SQLITE_SCHEMA is returned and none of the output variables are
** populated.
**
** Otherwise, if it is not NULL, variable *pzTab is set to point to a
** nul-terminated copy of the table name. *pazCol (if not NULL) is set to
** point to an array of pointers to column names. And *pabPK (again, if not
** NULL) is set to point to an array of booleans - true if the corresponding
** column is part of the primary key.
**
** For example, if the table is declared as:
**
**     CREATE TABLE tbl1(w, x, y, z, PRIMARY KEY(w, z));
**
** Then the three output variables are populated as follows:
**
**     *pzTab  = "tbl1"
**     *pazCol = {"w", "x", "y", "z"}
**     *pabPK  = {1, 0, 0, 1}
**
** All returned buffers are part of the same single allocation, which must
** be freed using sqlite3_free() by the caller. If pazCol was not NULL, then
** pointer *pazCol should be freed to release all memory. Otherwise, pointer
** *pabPK. It is illegal for both pazCol and pabPK to be NULL.
*/
static int sessionTableInfo(
  sqlite3 *db,                    /* Database connection */
  const char *zDb,                /* Name of attached database (e.g. "main") */
  const char *zThis,              /* Table name */
  int nCol,                       /* Expected number of columns */
  const char **pzTab,             /* OUT: Copy of zThis */
  const char ***pazCol,           /* OUT: Array of column names for table */
  u8 **pabPK                      /* OUT: Array of booleans - true for PK col */
){
  char *zPragma;
  sqlite3_stmt *pStmt;
  int rc;
  int nByte;
  int nDbCol = 0;
  int nThis;
  int i;
  u8 *pAlloc;
  u8 *pFree = 0;
  char **azCol;
  u8 *abPK;

  assert( pazCol || pabPK );

  nThis = strlen(zThis);
  zPragma = sqlite3_mprintf("PRAGMA '%q'.table_info('%q')", zDb, zThis);
  if( !zPragma ) return SQLITE_NOMEM;

  rc = sqlite3_prepare_v2(db, zPragma, -1, &pStmt, 0);
  sqlite3_free(zPragma);
  if( rc!=SQLITE_OK ) return rc;

  nByte = nThis + 1;
  while( SQLITE_ROW==sqlite3_step(pStmt) ){
    nByte += sqlite3_column_bytes(pStmt, 1);
    nDbCol++;
  }
  rc = sqlite3_reset(pStmt);

  if( nDbCol!=nCol ){
    rc = SQLITE_SCHEMA;
  }
  if( rc==SQLITE_OK ){
    nByte += nDbCol * (sizeof(const char *) + sizeof(u8) + 1);
    pAlloc = sqlite3_malloc(nByte);
    if( pAlloc==0 ){
      rc = SQLITE_NOMEM;
    }
  }
  if( rc==SQLITE_OK ){
    pFree = pAlloc;
    if( pazCol ){
      azCol = (char **)pAlloc;
      pAlloc = (u8 *)&azCol[nCol];
    }
    if( pabPK ){
      abPK = (u8 *)pAlloc;
      pAlloc = &abPK[nCol];
    }
    if( pzTab ){
      memcpy(pAlloc, zThis, nThis+1);
      *pzTab = (char *)pAlloc;
      pAlloc += nThis+1;
    }
  
    i = 0;
    while( SQLITE_ROW==sqlite3_step(pStmt) ){
      int nName = sqlite3_column_bytes(pStmt, 1);
      const unsigned char *zName = sqlite3_column_text(pStmt, 1);
      if( zName==0 ) break;
      if( pazCol ){
        memcpy(pAlloc, zName, nName+1);
        azCol[i] = (char *)pAlloc;
        pAlloc += nName+1;
      }
      if( pabPK ) abPK[i] = sqlite3_column_int(pStmt, 5);
      i++;
    }
    rc = sqlite3_reset(pStmt);
  
  }

  /* If successful, populate the output variables. Otherwise, zero them and
  ** free any allocation made. An error code will be returned in this case.
  */
  if( rc==SQLITE_OK ){
    if( pazCol ) *pazCol = (const char **)azCol;
    if( pabPK ) *pabPK = abPK;
  }else{
    if( pazCol ) *pazCol = 0;
    if( pabPK ) *pabPK = 0;
    if( pzTab ) *pzTab = 0;
    sqlite3_free(pFree);
  }
  sqlite3_finalize(pStmt);
  return rc;
}

/*
** This function is only called from within a pre-update handler for a
** write to table pTab, part of session pSession. If this is the first
** write to this table, set the SessionTable.nCol variable to the number
** of columns in the table.
**
** Otherwise, if this is not the first time this table has been written
** to, check that the number of columns in the table has not changed. If
** it has not, return zero.
**
** If the number of columns in the table has changed since the last write
** was recorded, set the session error-code to SQLITE_SCHEMA and return
** non-zero. Users are not allowed to change the number of columns in a table
** for which changes are being recorded by the session module. If they do so, 
** it is an error.
*/
static int sessionInitTable(sqlite3_session *pSession, SessionTable *pTab){
  if( pTab->nCol==0 ){
    assert( pTab->azCol==0 || pTab->abPK==0 );
    pTab->nCol = sqlite3_preupdate_count(pSession->db);
    pSession->rc = sessionTableInfo(pSession->db, pSession->zDb, 
        pTab->zName, pTab->nCol, 0, &pTab->azCol, &pTab->abPK
    );
  }else if( pTab->nCol!=sqlite3_preupdate_count(pSession->db) ){
    pSession->rc = SQLITE_SCHEMA;
  }
  return pSession->rc;
}

static void sessionPreupdateOneChange(
  int op,
  sqlite3_session *pSession,
  SessionTable *pTab
){
  sqlite3 *db = pSession->db;
  SessionChange *pChange;
  SessionChange *pC;
  int iHash; 
  int rc = SQLITE_OK;

  if( pSession->rc ) return;

  /* Load table details if required */
  if( sessionInitTable(pSession, pTab) ) return;

  /* Grow the hash table if required */
  if( sessionGrowHash(pSession, pTab) ) return;

  /* Search the hash table for an existing entry for rowid=iKey2. If
   ** one is found, store a pointer to it in pChange and unlink it from
   ** the hash table. Otherwise, set pChange to NULL.
   */
  rc = sessionPreupdateHash(db, pTab, op==SQLITE_INSERT, &iHash);
  for(pC=pTab->apChange[iHash]; rc==SQLITE_OK && pC; pC=pC->pNext){
    int bEqual;
    rc = sessionPreupdateEqual(db, pTab, pC, op==SQLITE_INSERT, &bEqual);
    if( bEqual ) break;
  }
  if( pC==0 ){
    /* Create a new change object containing all the old values (if
     ** this is an SQLITE_UPDATE or SQLITE_DELETE), or just the PK
     ** values (if this is an INSERT). */
    int nByte;              /* Number of bytes to allocate */
    int i;                  /* Used to iterate through columns */

    pTab->nEntry++;

    /* Figure out how large an allocation is required */
    nByte = sizeof(SessionChange);
    for(i=0; i<pTab->nCol && rc==SQLITE_OK; i++){
      sqlite3_value *p = 0;
      if( op!=SQLITE_INSERT ){
        rc = sqlite3_preupdate_old(pSession->db, i, &p);
      }else if( 1 || pTab->abPK[i] ){
        rc = sqlite3_preupdate_new(pSession->db, i, &p);
      }
      if( p && rc==SQLITE_OK ){
        rc = sessionSerializeValue(0, p, &nByte);
      }
    }

    /* Allocate the change object */
    pChange = (SessionChange *)sqlite3_malloc(nByte);
    if( !pChange ){
      rc = SQLITE_NOMEM;
    }else{
      memset(pChange, 0, sizeof(SessionChange));
      pChange->aRecord = (u8 *)&pChange[1];
    }

    /* Populate the change object */
    nByte = 0;
    for(i=0; i<pTab->nCol && rc==SQLITE_OK; i++){
      sqlite3_value *p = 0;
      if( op!=SQLITE_INSERT ){
        rc = sqlite3_preupdate_old(pSession->db, i, &p);
      }else if( 1 || pTab->abPK[i] ){
        rc = sqlite3_preupdate_new(pSession->db, i, &p);
      }
      if( p && rc==SQLITE_OK ){
        rc = sessionSerializeValue(&pChange->aRecord[nByte], p, &nByte);
      }
    }
    pChange->nRecord = nByte;

    /* If an error has occurred, mark the session object as failed. */
    if( rc!=SQLITE_OK ){
      sqlite3_free(pChange);
      pSession->rc = rc;
    }else{
      /* Add the change back to the hash-table */
      pChange->bInsert = (op==SQLITE_INSERT);
      pChange->pNext = pTab->apChange[iHash];
      pTab->apChange[iHash] = pChange;
    }
  }
}

/*
** The 'pre-update' hook registered by this module with SQLite databases.
*/
static void xPreUpdate(
  void *pCtx,                     /* Copy of third arg to preupdate_hook() */

  sqlite3_session *pSession;
  int nDb = strlen(zDb);
  int nName = strlen(zDb);
 
  for(pSession=(sqlite3_session *)pCtx; pSession; pSession=pSession->pNext){
    SessionTable *pTab;


    /* If this session is attached to a different database ("main", "temp" 
    ** etc.), or if it is not currently enabled, there is nothing to do. Skip 
    ** to the next session object attached to this database. */
    if( pSession->bEnable==0 ) continue;
    if( pSession->rc ) continue;
    if( sqlite3_strnicmp(zDb, pSession->zDb, nDb+1) ) continue;

    for(pTab=pSession->pTable; pTab; pTab=pTab->pNext){
      if( 0==sqlite3_strnicmp(pTab->zName, zName, nName+1) ){




        sessionPreupdateOneChange(op, pSession, pTab);





















        if( op==SQLITE_UPDATE ){







          sessionPreupdateOneChange(SQLITE_INSERT, pSession, pTab);







        }


































        break;
      }
    }
  }
}

/*

      SessionChange *p;
      SessionChange *pNext;
      for(p=pTab->apChange[i]; p; p=pNext){
        pNext = p->pNext;
        sqlite3_free(p);
      }
    }
    sqlite3_free(pTab->azCol);
    sqlite3_free(pTab->apChange);
    sqlite3_free(pTab);
  }

  /* Free the session object itself. */
  sqlite3_free(pSession);
}

    }else{
      sessionAppendBlob(pBuf, buf2.aBuf, buf2.nBuf, pRc);
      sqlite3_free(buf2.aBuf);
    }
  }
}




























static int sessionSelectStmt(
  sqlite3 *db,                    /* Database handle */

  const char *zTab,               /* Table name */
  int nCol,
  const char **azCol,


  u8 *abPK,
  sqlite3_stmt **ppStmt
){
  int rc = SQLITE_OK;
  int i;
  const char *zSep = "";
  SessionBuffer buf = {0, 0, 0};

  sessionAppendStr(&buf, "SELECT * FROM ", &rc);
  sessionAppendIdent(&buf, zTab, &rc);
  sessionAppendStr(&buf, " WHERE ", &rc);
  for(i=0; i<nCol; i++){
    if( abPK[i] ){
      sessionAppendStr(&buf, zSep, &rc);
      sessionAppendIdent(&buf, azCol[i], &rc);
      sessionAppendStr(&buf, " = ?", &rc);
      sessionAppendInteger(&buf, i+1, &rc);
      zSep = " AND ";
    }
  }
  if( rc==SQLITE_OK ){
    rc = sqlite3_prepare_v2(db, (char *)buf.aBuf, buf.nBuf, ppStmt, 0);
  }
  sqlite3_free(buf.aBuf);
  return rc;
}

static int sessionSelectBind(
  sqlite3_stmt *pSelect,
  int nCol,
  u8 *abPK,
  u8 *aRecord,
  int nRecord
){
  int i;

  int rc = SQLITE_OK;

  u8 *a = aRecord;

  for(i=0; i<nCol && rc==SQLITE_OK; i++){
    int eType = *a++;



    switch( eType ){
      case SQLITE_NULL:
        if( abPK[i] ) rc = sqlite3_bind_null(pSelect, i+1);

        break;



      case SQLITE_INTEGER: {
        if( abPK[i] ){
          i64 iVal = sessionGetI64(a);
          rc = sqlite3_bind_int64(pSelect, i+1, iVal);

        }
        a += 8;
        break;
      }



      case SQLITE_FLOAT: {


        if( abPK[i] ){
          double rVal;
          i64 iVal = sessionGetI64(a);
          memcpy(&rVal, &iVal, 8);
          rc = sqlite3_bind_int64(pSelect, i+1, rVal);
        }


        a += 8;
        break;


      }


      case SQLITE_TEXT: {
        int n;
        a += sessionVarintGet(a, &n);
        if( abPK[i] ){
          rc = sqlite3_bind_text(pSelect, i+1, (char *)a, n, SQLITE_TRANSIENT);
        }



        a += n;
        break;
      }


      case SQLITE_BLOB: {
        int n;

        a += sessionVarintGet(a, &n);
        if( abPK[i] ){
          rc = sqlite3_bind_blob(pSelect, i+1, a, n, SQLITE_TRANSIENT);


        }

        a += n;

        break;
      }
    }
  }













  return rc;
}

/*
** Obtain a changeset object containing all changes recorded by the 
** session object passed as the first argument.
**

  ** this call will be a no-op.  */
  *pnChangeset = 0;
  *ppChangeset = 0;
  rc = pSession->rc;

  for(pTab=pSession->pTable; rc==SQLITE_OK && pTab; pTab=pTab->pNext){
    if( pTab->nEntry ){
      int nCol = pTab->nCol;      /* Local copy of member variable */
      u8 *abPK = pTab->abPK;      /* Local copy of member variable */
      int i;
      sqlite3_stmt *pStmt = 0;
      int bNoop = 1;
      int nRewind = buf.nBuf;


      /* Write a table header */
      sessionAppendByte(&buf, 'T', &rc);
      sessionAppendVarint(&buf, nCol, &rc);
      sessionAppendBlob(&buf, (u8 *)pTab->zName, strlen(pTab->zName)+1, &rc);

      /* Build and compile a statement to execute: */
      if( rc==SQLITE_OK ){

        rc = sessionSelectStmt(db, pTab->zName, nCol, pTab->azCol, abPK,&pStmt);





      }



      if( rc==SQLITE_OK && nCol!=sqlite3_column_count(pStmt) ){
        rc = SQLITE_SCHEMA;





      }

      for(i=0; i<pTab->nChange; i++){
        SessionChange *p;         /* Used to iterate through changes */

        for(p=pTab->apChange[i]; rc==SQLITE_OK && p; p=p->pNext){
          rc = sessionSelectBind(pStmt, nCol, abPK, p->aRecord, p->nRecord);
          if( rc==SQLITE_OK ){
            if( sqlite3_step(pStmt)==SQLITE_ROW ){
              int iCol;
              if( p->bInsert ){


                sessionAppendByte(&buf, SQLITE_INSERT, &rc);
                for(iCol=0; iCol<nCol; iCol++){
                  sessionAppendCol(&buf, pStmt, iCol, &rc);
                }
              }else{
                sessionAppendUpdate(&buf, pStmt, p, abPK, &rc);
              }
              bNoop = 0;
            }else if( !p->bInsert ){
              /* A DELETE change */
              sessionAppendByte(&buf, SQLITE_DELETE, &rc);
              sessionAppendBlob(&buf, p->aRecord, p->nRecord, &rc);
              bNoop = 0;
            }
            rc = sqlite3_reset(pStmt);
          }
        }
      }

      sqlite3_finalize(pStmt);


      if( bNoop ){
        buf.nBuf = nRewind;
      }
    }
  }

** pointing to the prepared version of the SQL statement.
*/
static int sessionSelectRow(
  sqlite3 *db,                    /* Database handle */
  const char *zTab,               /* Table name */
  SessionApplyCtx *p              /* Session changeset-apply context */
){




  return sessionSelectStmt(db, zTab, p->nCol, p->azCol, p->abPK, &p->pSelect);

















}

/*
** Formulate and prepare an INSERT statement to add a record to table zTab.
** For example:
**
**     INSERT INTO main."zTab" VALUES(?1, ?2, ?3 ...);

    set changeset [sqlite3changeset_invert [$session changeset]]
    sqlite3session_foreach c [set changeset] { lappend x [set c] }
    set x
  }]] [list $r]
}

do_execsql_test 1.0 {
  CREATE TABLE t1(x PRIMARY KEY, y);
  INSERT INTO t1 VALUES('abc', 'def');
}

#-------------------------------------------------------------------------
# Test creating, attaching tables to and deleting session objects.
#
do_test 1.1 { sqlite3session S db main } {S}

  {INSERT t1 {} {i 1 t Sukhothai}}
  {INSERT t1 {} {i 2 t Ayutthaya}}
  {INSERT t1 {} {i 3 t Thonburi}}
}
do_test 2.2.4 { S delete } {}

do_test 2.3.1 {
  execsql { DELETE FROM t1 }
  sqlite3session S db main
  execsql { INSERT INTO t1 VALUES(1, 'Sukhothai') }
  execsql { INSERT INTO t1 VALUES(2, 'Ayutthaya') }
  execsql { INSERT INTO t1 VALUES(3, 'Thonburi') }
  S attach t1
  execsql { 
    UPDATE t1 SET x = 10 WHERE x = 1;
    UPDATE t1 SET y = 'Surin' WHERE x = 2;
    UPDATE t1 SET x = 20, y = 'Thapae' WHERE x = 3;
  }
} {}

do_changeset_test 2.3.2 S {
  {INSERT t1 {} {i 10 t Sukhothai}} 
  {DELETE t1 {i 1 t Sukhothai} {}} 
  {UPDATE t1 {i 2 t Ayutthaya} {{} {} t Surin}} 
  {DELETE t1 {i 3 t Thonburi} {}} 
  {INSERT t1 {} {i 20 t Thapae}} 
}

do_changeset_invert_test 2.3.3 S {
  {DELETE t1 {i 10 t Sukhothai} {}} 
  {INSERT t1 {} {i 1 t Sukhothai}} 
  {UPDATE t1 {{} {} t Surin} {i 2 t Ayutthaya}} 
  {INSERT t1 {} {i 3 t Thonburi}} 
  {DELETE t1 {i 20 t Thapae} {}}
}
do_test 2.3.4 { S delete } {}

do_test 2.4.1 {
  sqlite3session S db main
  S attach t1
  execsql { INSERT INTO t1 VALUES(100, 'Bangkok') }

  execsql { 
    CREATE TABLE t1(a PRIMARY KEY, b);
    INSERT INTO t1 VALUES(1, 'one');
    INSERT INTO t1 VALUES(2, 'two');
  } db 
} {}
do_db2_test 3.1.1 "INSERT INTO t1 VALUES(6, 'VI')"
do_conflict_test 3.1.2 -tables t1 -sql {
  INSERT INTO t1 VALUES(3, 'three');
  INSERT INTO t1 VALUES(4, 'four');
  INSERT INTO t1 VALUES(5, 'five');
  INSERT INTO t1 VALUES(6, 'six');
  INSERT INTO t1 VALUES(7, 'seven');
  INSERT INTO t1 VALUES(8, NULL);
} -conflicts {

  {INSERT t1 CONSTRAINT {i 8 n {}}}
  {INSERT t1 CONFLICT {i 6 t six} {i 6 t VI}}
}

do_db2_test 3.1.3 "SELECT * FROM t1" {
  6 VI 3 three 4 four 5 five 7 seven
}
do_execsql_test 3.1.4 "SELECT * FROM t1" {
  1 one 2 two 3 three 4 four 5 five 6 six 7 seven 8 {}
}

# Test DELETE changesets.
#
do_execsql_test 3.2.1 {
  PRAGMA foreign_keys = on;

}
do_conflict_test 3.3.3 -tables t4 -sql {
  UPDATE t4 SET a = -1 WHERE b = 2;
  UPDATE t4 SET a = -1 WHERE b = 5;
  UPDATE t4 SET a = NULL WHERE c = 9;
  UPDATE t4 SET a = 'x' WHERE b = 11;
} -conflicts {
  {UPDATE t4 CONSTRAINT {i 7 i 8 i 9} {n {} {} {} {} {}}}
  {UPDATE t4 DATA {i 1 i 2 i 3} {i -1 {} {} {} {}} {i 0 i 2 i 3}}
  {UPDATE t4 NOTFOUND {i 4 i 5 i 6} {i -1 {} {} {} {}}}

}
do_db2_test     3.3.4 { SELECT * FROM t4 } {0 2 3 4 5 7 7 8 9 x 11 12}
do_execsql_test 3.3.5 { SELECT * FROM t4 } {-1 2 3 -1 5 6 {} 8 9 x 11 12}

#-------------------------------------------------------------------------
# This next block of tests verifies that values returned by the conflict
# handler are intepreted correctly.

proc xConflict {args} {
  lappend ::xConflict $args
  return $::conflict_return
}

foreach {tn conflict_return after} {
  1 OMIT      {1 2 value1   4 5 7       10 x x}
  2 REPLACE   {1 2 value1   4 5 value2  10 8 9}
} {
  test_reset

  do_test 4.$tn.1 {
    foreach db {db db2} {
      execsql { 
        CREATE TABLE t1(a, b, c, PRIMARY KEY(a));

  } {}

  do_conflict_test 4.$tn.2 -tables t1 -sql {
    UPDATE t1 SET c = 'value1' WHERE a = 1;       -- no conflict
    UPDATE t1 SET c = 'value2' WHERE a = 4;       -- DATA conflict
    UPDATE t1 SET a = 10 WHERE a = 7;             -- CONFLICT conflict
  } -conflicts {
    {INSERT t1 CONFLICT {i 10 i 8 i 9} {i 10 t x t x}}
    {UPDATE t1 DATA {i 4 {} {} i 6} {{} {} {} {} t value2} {i 4 i 5 i 7}}

  }

  do_db2_test 4.$tn.3 "SELECT * FROM t1 ORDER BY a" $after
}

foreach {tn conflict_return} {
  1 OMIT