SQLite

/*
** 2003 April 6
**
** 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 code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.77 2004/11/12 16:12:00 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
# include "pager.h"
# include "btree.h"

        if( !pEnc->zName ){
          sqlite3ErrorMsg(pParse, "unsupported encoding: %s", zRight);
        }
      }
    }
  }else
  /*
  **   PRAGMA [database.]schema_version
  **   PRAGMA [database.]schema_version = <integer>
  **
  **   PRAGMA [database.]user_version
  **   PRAGMA [database.]user_version = <integer>
  **
  ** The pragma's schema_version and user_version are used to set or get
  ** the value of the schema-version and user-version, respectively. Both
  ** the schema-version and the user-version are 32-bit signed integers
  ** stored in the database header.
  **
  ** The schema-cookie is usually only manipulated internally by SQLite. It
  ** is incremented by SQLite whenever the database schema is modified (by
  ** creating or dropping a table or index). The schema version is used by
  ** SQLite each time a query is executed to ensure that the internal cache
  ** of the schema used when compiling the SQL query matches the schema of
  ** the database against which the compiled query is actually executed.
  ** Subverting this mechanism by using "PRAGMA schema_version" to modify
  ** the schema-version is potentially dangerous and may lead to program
  ** crashes or database corruption. Use with caution!
  **
  ** The user-version is not used internally by SQLite. It may be used by
  ** applications for any purpose.
  */
  if( sqlite3StrICmp(zLeft, "schema_version")==0 ||
      sqlite3StrICmp(zLeft, "user_version")==0 ){

    int iCookie;   /* Cookie index. 0 for schema-cookie, 6 for user-cookie. */
    if( zLeft[0]=='s' || zLeft[0]=='S' ){
      iCookie = 0;
    }else{
      iCookie = 5;
    }

#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests for the PRAGMA command.
#
# $Id: pragma.test,v 1.23 2004/11/12 16:12:00 danielk1977 Exp $

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

# Test organization:
#
# pragma-1.*: Test cache_size, default_cache_size and synchronous on main db.

  execsql {
    pragma lock_status;
  }
} {main unlocked temp closed}


#----------------------------------------------------------------------
# Test cases pragma-8.* test the "PRAGMA schema_version" and "PRAGMA
# user_version" statements.
#
# pragma-8.1: PRAGMA schema_version
# pragma-8.2: PRAGMA user_version
#

# First check that we can set the schema version and then retrieve the
# same value.
do_test pragma-8.1.1 {
  execsql {
    PRAGMA schema_version = 105;
  }
} {}
do_test pragma-8.1.2 {
  execsql {
    PRAGMA schema_version;
  }
} 105
do_test pragma-8.1.3 {
  execsql {
    PRAGMA schema_version = 106;
  }
} {}
do_test pragma-8.1.4 {
  execsql {
    PRAGMA schema_version;
  }
} 106

# Check that creating a table modifies the schema-version (this is really
# to verify that the value being read is in fact the schema version).
do_test pragma-8.1.5 {
  execsql {
    CREATE TABLE t4(a, b, c);
    INSERT INTO t4 VALUES(1, 2, 3);
    SELECT * FROM t4;
  }
} {1 2 3}
do_test pragma-8.1.6 {
  execsql {
    PRAGMA schema_version;
  }
} 107

# Now open a second connection to the database. Ensure that changing the
# schema-version using the first connection forces the second connection
# to reload the schema. This has to be done using the C-API test functions,
# because the TCL API accounts for SCHEMA_ERROR and retries the query.
do_test pragma-8.1.7 {
  set ::DB2 [sqlite3 db2 test.db]
  execsql {
    SELECT * FROM t4;
  } db2
} {1 2 3}
do_test pragma-8.1.8 {
  execsql {
    PRAGMA schema_version = 108;
  }
} {}
do_test pragma-8.1.9 {
  set ::STMT [sqlite3_prepare $::DB2 "SELECT * FROM t4" -1 DUMMY]
  sqlite3_step $::STMT
} SQLITE_ERROR
do_test pragma-8.1.10 {
  sqlite3_finalize $::STMT
} SQLITE_SCHEMA

# Make sure the schema-version can be manipulated in an attached database.
file delete -force test2.db
file delete -force test2.db-journal
do_test pragma-8.1.11 {
  execsql {
    ATTACH 'test2.db' AS aux;
    CREATE TABLE aux.t1(a, b, c);
    PRAGMA aux.schema_version = 205;
  }
} {}
do_test pragma-8.1.12 {
  execsql {
    PRAGMA aux.schema_version;
  }
} 205
do_test pragma-8.1.13 {
  execsql {
    PRAGMA schema_version;
  }
} 108

# And check that modifying the schema-version in an attached database
# forces the second connection to reload the schema.
do_test pragma-8.1.14 {
  set ::DB2 [sqlite3 db2 test.db]
  execsql {
    ATTACH 'test2.db' AS aux;
    SELECT * FROM aux.t1;
  } db2
} {}
do_test pragma-8.1.15 {
  execsql {
    PRAGMA aux.schema_version = 206;
  }
} {}
do_test pragma-8.1.16 {
  set ::STMT [sqlite3_prepare $::DB2 "SELECT * FROM aux.t1" -1 DUMMY]
  sqlite3_step $::STMT
} SQLITE_ERROR
do_test pragma-8.1.17 {
  sqlite3_finalize $::STMT
} SQLITE_SCHEMA
do_test pragma-8.1.18 {
  db2 close
} {}

# Now test that the user-version can be read and written (and that we aren't
# accidentally manipulating the schema-version instead).
do_test pragma-8.2.1 {
  execsql {
    PRAGMA user_version;
  }
} {0}
do_test pragma-8.2.2 {
  execsql {
    PRAGMA user_version = 2;
  }
} {}
do_test pragma-8.2.3 {
  execsql {
    PRAGMA user_version;
  }
} {2}
do_test pragma-8.2.4 {
  execsql {
    PRAGMA schema_version;
  }
} {108}

# Check that the user-version in the auxilary database can be manipulated (
# and that we aren't accidentally manipulating the same in the main db).
do_test pragma-8.2.5 {
  execsql {
    PRAGMA aux.user_version;
  }
} {0}
do_test pragma-8.2.6 {
  execsql {
    PRAGMA aux.user_version = 3;
  }
} {}
do_test pragma-8.2.7 {
  execsql {
    PRAGMA aux.user_version;
  }
} {3}
do_test pragma-8.2.8 {
  execsql {
    PRAGMA main.user_version;
  }
} {2}

# Now check that a ROLLBACK resets the user-version if it has been modified
# within a transaction.
do_test pragma-8.2.9 {
  execsql {
    BEGIN;
    PRAGMA aux.user_version = 10;
    PRAGMA user_version = 11;
  }
} {}
do_test pragma-8.2.10 {
  execsql {
    PRAGMA aux.user_version;
  }
} {10}
do_test pragma-8.2.11 {
  execsql {
    PRAGMA main.user_version;
  }
} {11}
do_test pragma-8.2.12 {
  execsql {
    ROLLBACK;
    PRAGMA aux.user_version;
  }
} {3}
do_test pragma-8.2.13 {
  execsql {
    PRAGMA main.user_version;
  }
} {2}

# Try a negative value for the user-version
do_test pragma-8.2.14 {
  execsql {
    PRAGMA user_version = -450;
  }
} {}
do_test pragma-8.2.15 {
  execsql {
    PRAGMA user_version;
  }
} {-450}

finish_test

#
# Run this Tcl script to generate the pragma.html file.
#
set rcsid {$Id: pragma.tcl,v 1.3 2004/11/12 16:12:00 danielk1977 Exp $}
source common.tcl
header {Pragma statements supported by SQLite}

puts {
<p>The <a href="#syntax">PRAGMA command</a> is a special command used to 
modify the operation of the SQLite library or to query the library for 
internal (non-table) data. The PRAGMA command is issued using the same

<p>The available pragmas fall into four basic categories:</p>
<ul>
<li>Pragmas used to <a href="#schema">query the schema</a> of the current 
    database.
<li>Pragmas used to <a href="#modify">modify the operation</a> of the 
    SQLite library in some manner, or to query for the current mode of 
    operation.
<li>Pragmas used to <a href="#version">query or modify the databases two 
    version values</a>, the schema-version and the user-version.
<li>Pragmas used to <a href="#debug">debug the library</a> and verify that
    database files are not corrupted.
</ul>
}

Section {PRAGMA command syntax} syntax

    <p>For each column in the named table, invoke the callback function
    once with information about that column, including the column name,
    data type, whether or not the column can be NULL, and the default
    value for the column.</p></li>
</ul>
}

Section {Pragmas to query/modify version values} version

puts {

<ul>
<li><p><b>PRAGMA [database.]schema_version; 
       <br>PRAGMA [database.]schema_version = </b><i>integer </i><b>;
       <br>PRAGMA [database.]user_version;
       <br>PRAGMA [database.]user_version = </b><i>integer </i><b>;</b>

  
<p>    The pragmas schema_version and user_version are used to set or get
       the value of the schema-version and user-version, respectively. Both
       the schema-version and the user-version are 32-bit signed integers
       stored in the database header.</p>
  
<p>    The schema-version is usually only manipulated internally by SQLite.  
       It is incremented by SQLite whenever the database schema is modified 
       (by creating or dropping a table or index). The schema version is 
       used by SQLite each time a query is executed to ensure that the 
       internal cache of the schema used when compiling the SQL query matches 
       the schema of the database against which the compiled query is actually 
       executed.  Subverting this mechanism by using "PRAGMA schema_version" 
       to modify the schema-version is potentially dangerous and may lead 
       to program crashes or database corruption. Use with caution!</p>
  
<p>    The user-version is not used internally by SQLite. It may be used by
       applications for any purpose.</p>
</li>
</ul>
}

Section {Pragmas to debug the library} debug