SQLite

**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.213 2004/06/10 00:29:09 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

      sqlite3ErrorMsg(pParse, "no such table: %s.%s", zDbase, zName);
    }else if( sqlite3FindTable(pParse->db, zName, 0)!=0 ){
      sqlite3ErrorMsg(pParse, "table \"%s\" is not in database \"%s\"",
         zName, zDbase);
    }else{
      sqlite3ErrorMsg(pParse, "no such table: %s", zName);
    }
    pParse->checkSchema = 1;
  }
  return p;
}

/*
** Locate the in-memory structure that describes 
** a particular index given the name of that index

  Table *pTab;
  zName = sqlite3TableNameFromToken(pTok);
  if( zName==0 ) return 0;
  pTab = sqlite3FindTable(pParse->db, zName, 0);
  sqliteFree(zName);
  if( pTab==0 ){
    sqlite3ErrorMsg(pParse, "no such table: %T", pTok);
    pParse->checkSchema = 1;
  }
  return pTab;
}

/*
** This routine is called to do the work of a DROP TABLE statement.
** pName is the name of the table to be dropped.

  sqlite *db = pParse->db;

  if( pParse->nErr || sqlite3_malloc_failed ) return;
  assert( pName->nSrc==1 );
  pIndex = sqlite3FindIndex(db, pName->a[0].zName, pName->a[0].zDatabase);
  if( pIndex==0 ){
    sqlite3ErrorMsg(pParse, "no such index: %S", pName, 0);
    pParse->checkSchema = 1;
    goto exit_drop_index;
  }
  if( pIndex->autoIndex ){
    sqlite3ErrorMsg(pParse, "index associated with UNIQUE "
      "or PRIMARY KEY constraint cannot be dropped", 0);
    goto exit_drop_index;
  }

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.211 2004/06/10 00:29:09 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** A pointer to this structure is used to communicate information

  }
  return db->zErrMsg16;
}

int sqlite3_errcode(sqlite3 *db){
  return db->errCode;
}

/*
** Check schema cookies in all databases except TEMP.  If any cookie is out
** of date, return 0.  If all schema cookies are current, return 1.
*/
static int schemaIsValid(sqlite *db){
  int iDb;
  int rc;
  BtCursor *curTemp;
  int cookie;
  int allOk = 1;

  for(iDb=0; allOk && iDb<db->nDb; iDb++){
    Btree *pBt;
    if( iDb==1 ) continue;
    pBt = db->aDb[iDb].pBt;
    if( pBt==0 ) continue;
    rc = sqlite3BtreeCursor(pBt, MASTER_ROOT, 0, 0, 0, &curTemp);
    if( rc==SQLITE_OK ){
      rc = sqlite3BtreeGetMeta(pBt, 1, &cookie);
      if( rc==SQLITE_OK && cookie!=db->aDb[iDb].schema_cookie ){
        allOk = 0;
      }
      sqlite3BtreeCloseCursor(curTemp);
    }
  }
  return allOk;
}

/*
** Compile the UTF-8 encoded SQL statement zSql into a statement handle.
*/
int sqlite3_prepare(
  sqlite3 *db,              /* Database handle. */
  const char *zSql,         /* UTF-8 encoded SQL statement. */

    rc = SQLITE_NOMEM;
    sqlite3RollbackAll(db);
    sqlite3ResetInternalSchema(db, 0);
    db->flags &= ~SQLITE_InTrans;
    goto prepare_out;
  }
  if( sParse.rc==SQLITE_DONE ) sParse.rc = SQLITE_OK;
  if( sParse.checkSchema && !schemaIsValid(db) ){
    sParse.rc = SQLITE_SCHEMA;
  }
  if( sParse.rc==SQLITE_SCHEMA ){
    sqlite3ResetInternalSchema(db, 0);
  }
  assert( ppStmt );
  *ppStmt = (sqlite3_stmt*)sParse.pVdbe;
  if( pzTail ) *pzTail = sParse.zTail;
  rc = sParse.rc;

/*
** 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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.277 2004/06/10 00:29:10 drh Exp $
*/
#include "config.h"
#include "sqlite3.h"
#include "hash.h"
#include "parse.h"
#include <stdio.h>
#include <stdlib.h>

  Table *pNewTable;    /* A table being constructed by CREATE TABLE */
  Vdbe *pVdbe;         /* An engine for executing database bytecode */
  u8 colNamesSet;      /* TRUE after OP_ColumnName has been issued to pVdbe */
  u8 explain;          /* True if the EXPLAIN flag is found on the query */
  u8 nameClash;        /* A permanent table name clashes with temp table name */
  u8 useAgg;           /* If true, extract field values from the aggregator
                       ** while generating expressions.  Normally false */
  u8 checkSchema;      /* Causes schema cookie check after an error */
  int nErr;            /* Number of errors seen */
  int nTab;            /* Number of previously allocated VDBE cursors */
  int nMem;            /* Number of memory cells used so far */
  int nSet;            /* Number of sets used so far */
  int nAgg;            /* Number of aggregate expressions */
  int nVar;            /* Number of '?' variables seen in the SQL so far */
  AggExpr *aAgg;       /* An array of aggregate expressions */

# 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 implements regression tests for SQLite library.  The
# focus of this script is database locks.
#
# $Id: lock.test,v 1.23 2004/06/10 00:29:12 drh Exp $


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

# Create an alternative connection to the database
#

  execsql {INSERT INTO t1 VALUES(1,2)}
  execsql {SELECT * FROM t1}
} {1 2}
do_test lock-1.7.1 {
  catchsql {SELECT * FROM t1} db2
} {1 {no such table: t1}}
do_test lock-1.7.2 {

  catchsql {SELECT * FROM t1} db2
} {0 {1 2}}
do_test lock-1.8 {
  execsql {UPDATE t1 SET a=b, b=a} db2
  execsql {SELECT * FROM t1} db2
} {2 1}
do_test lock-1.9 {
  execsql {SELECT * FROM t1}
} {2 1}
do_test lock-1.10 {
  execsql {BEGIN TRANSACTION}
  execsql {UPDATE t1 SET a = 0 WHERE 0}
  execsql {SELECT * FROM t1}
} {2 1}
do_test lock-1.11 {
  catchsql {SELECT * FROM t1} db2
} {0 {2 1}}
do_test lock-1.12 {
  execsql {ROLLBACK}
  catchsql {SELECT * FROM t1}
} {0 {2 1}}

do_test lock-1.13 {
  execsql {CREATE TABLE t2(x int, y int)}

    }
    set r
  } {0 2}
}
integrity_check lock-1.23

# If one thread has a transaction another thread cannot start
# a transaction.  -> Not true in version 3.0.  But if one thread
# as a RESERVED lock another thread cannot acquire one.
#
do_test lock-2.1 {
  execsql {BEGIN TRANSACTION}
  execsql {UPDATE t1 SET a = 0 WHERE 0}
  execsql {BEGIN TRANSACTION} db2
  set r [catch {execsql {UPDATE t1 SET a = 0 WHERE 0} db2} msg]
  execsql {ROLLBACK} db2
  lappend r $msg
} {1 {database is locked}}

# A thread can read when another has a RESERVED lock.
#
do_test lock-2.2 {
  catchsql {SELECT * FROM t2} db2

} {0 {9 8}}

# If the other thread (the one that does not hold the transaction with
# a RESERVED lock) tries to get a RESERVED lock, we get a busy callback.
#
do_test lock-2.3 {
  proc callback {args} {
    set ::callback_value $args
    break
  }
  set ::callback_value {}
  db2 busy callback
  set r [catch {execsql {UPDATE t1 SET a=b, b=a} db2} msg]
  lappend r $msg
  lappend r $::callback_value
} {1 {database is locked} {{} 1}}
do_test lock-2.4 {
  proc callback {file count} {
    lappend ::callback_value $count
    if {$count>4} break
  }
  set ::callback_value {}
  db2 busy callback
  set r [catch {execsql {UPDATE t1 SET a=b, b=a} db2} msg]
  lappend r $msg
  lappend r $::callback_value
} {1 {database is locked} {1 2 3 4 5}}
do_test lock-2.5 {
  proc callback {file count} {
    lappend ::callback_value $count
    if {$count>4} break
  }
  set ::callback_value {}
  db2 busy callback
  set r [catch {execsql {SELECT * FROM t1} db2} msg]
  lappend r $msg
  lappend r $::callback_value
} {0 {2 1} {}}

# In this test, the 3rd invocation of the busy callback causes
# the first thread to release its transaction.  That allows the
# second thread to continue.
#
do_test lock-2.6 {
  proc callback {file count} {
    lappend ::callback_value $count
    if {$count>2} {
      execsql {ROLLBACK}
    }
  }
  set ::callback_value {}
  db2 busy callback
  set r [catch {execsql {SELECT * FROM t2} db2} msg]
  lappend r $msg
  lappend r $::callback_value
} {0 {9 8} {}}
do_test lock-2.7 {


  proc callback {file count} {
    lappend ::callback_value $count
    if {$count>2} {
      execsql {ROLLBACK}
    }
  }
  set ::callback_value {}

#
do_test lock-4.1 {
  db2 close
  catch {db eval ROLLBACK}
  db eval BEGIN
  db eval {UPDATE t1 SET a=0 WHERE 0}
  sqlite db2 ./test.db
  catchsql {UPDATE t1 SET a=0} db2

} {1 {database is locked}}
do_test lock-4.2 {
  set ::callback_value {}
  set rc [catch {db2 eval {UPDATE t1 SET a=0}} msg]
  lappend rc $msg $::callback_value
} {1 {database is locked} {}}
do_test lock-4.3 {
  proc callback {file count} {
    lappend ::callback_value $count
    if {$count>4} break
  }
  db2 busy callback
  set rc [catch {db2 eval {UPDATE t1 SET a=0}} msg]
  lappend rc $msg $::callback_value
} {1 {database is locked} {1 2 3 4 5}}
execsql {ROLLBACK}

# When one thread is writing, other threads cannot read.  Except if the
# writing thread is writing to its temporary tables, the other threads
# can still read.  -> Not so in 3.0.  One thread can read while another
# holds a RESERVED lock.
#
proc tx_exec {sql} {
  db2 eval $sql
}
do_test lock-5.1 {
  execsql {
    SELECT * FROM t1
  }
} {2 1}
do_test lock-5.2 {
  db function tx_exec tx_exec
  catchsql {
    INSERT INTO t1(a,b) SELECT 3, tx_exec('SELECT y FROM t2 LIMIT 1');
  }
} {0 {}}
do_test lock-5.3 {
  execsql {
    CREATE TEMP TABLE t3(x);
    SELECT * FROM t3;
  }
} {}
do_test lock-5.4 {
  catchsql {
    INSERT INTO t3 SELECT tx_exec('SELECT y FROM t2 LIMIT 1');
  }
} {0 {}}
do_test lock-5.5 {
  execsql {
    SELECT * FROM t3;
  }
} {8}
do_test lock-5.6 {
  catchsql {
    UPDATE t1 SET a=tx_exec('SELECT x FROM t2');
  }
} {0 {}}
do_test lock-5.7 {
  execsql {
    SELECT * FROM t1;
  }
} {9 1 9 8}
do_test lock-5.8 {
  catchsql {
    UPDATE t3 SET x=tx_exec('SELECT x FROM t2');
  }
} {0 {}}
do_test lock-5.9 {
  execsql {