CSqliteSchema

public function addForeignKey($name, $table, $columns, $refTable, $refColumns, $delete=null, $update=null)
{
    throw new CDbException(Yii::t('yii', 'Adding a foreign key constraint to an existing table is not supported by SQLite.'));
}

public function addPrimaryKey($name,$table,$columns)
{
    throw new CDbException(Yii::t('yii', 'Adding a primary key after table has been created is not supported by SQLite.'));
}

public function alterColumn($table, $column, $type)
{
    throw new CDbException(Yii::t('yii', 'Altering a DB column is not supported by SQLite.'));
}

public function checkIntegrity($check=true,$schema='')
{
    $this->getDbConnection()->createCommand('PRAGMA foreign_keys='.(int)$check)->execute();
}

protected function createColumn($column)
{
    $c=new CSqliteColumnSchema;
    $c->name=$column['name'];
    $c->rawName=$this->quoteColumnName($c->name);
    $c->allowNull=!$column['notnull'];
    $c->isPrimaryKey=$column['pk']!=0;
    $c->isForeignKey=false;
    $c->comment=null; // SQLite does not support column comments at all

    $c->init(strtolower($column['type']),$column['dflt_value']);
    return $c;
}

protected function createCommandBuilder()
{
    return new CSqliteCommandBuilder($this);
}

public function dropColumn($table, $column)
{
    throw new CDbException(Yii::t('yii', 'Dropping DB column is not supported by SQLite.'));
}

public function dropForeignKey($name, $table)
{
    throw new CDbException(Yii::t('yii', 'Dropping a foreign key constraint is not supported by SQLite.'));
}

public function dropIndex($name, $table)
{
    return 'DROP INDEX '.$this->quoteTableName($name);
}

public function dropPrimaryKey($name,$table)
{
    throw new CDbException(Yii::t('yii', 'Removing a primary key after table has been created is not supported by SQLite.'));

}

protected function findColumns($table)
{
    $sql="PRAGMA table_info({$table->rawName})";
    $columns=$this->getDbConnection()->createCommand($sql)->queryAll();
    if(empty($columns))
        return false;

    foreach($columns as $column)
    {
        $c=$this->createColumn($column);
        $table->columns[$c->name]=$c;
        if($c->isPrimaryKey)
        {
            if($table->primaryKey===null)
                $table->primaryKey=$c->name;
            elseif(is_string($table->primaryKey))
                $table->primaryKey=array($table->primaryKey,$c->name);
            else
                $table->primaryKey[]=$c->name;
        }
    }
    if(is_string($table->primaryKey) && !strncasecmp($table->columns[$table->primaryKey]->dbType,'int',3))
    {
        $table->sequenceName='';
        $table->columns[$table->primaryKey]->autoIncrement=true;
    }

    return true;
}

protected function findConstraints($table)
{
    $foreignKeys=array();
    $sql="PRAGMA foreign_key_list({$table->rawName})";
    $keys=$this->getDbConnection()->createCommand($sql)->queryAll();
    foreach($keys as $key)
    {
        $column=$table->columns[$key['from']];
        $column->isForeignKey=true;
        $foreignKeys[$key['from']]=array($key['table'],$key['to']);
    }
    $table->foreignKeys=$foreignKeys;
}

protected function findTableNames($schema='')
{
    $sql="SELECT DISTINCT tbl_name FROM sqlite_master WHERE tbl_name<>'sqlite_sequence'";
    return $this->getDbConnection()->createCommand($sql)->queryColumn();
}

protected function loadTable($name)
{
    $table=new CDbTableSchema;
    $table->name=$name;
    $table->rawName=$this->quoteTableName($name);

    if($this->findColumns($table))
    {
        $this->findConstraints($table);
        return $table;
    }
    else
        return null;
}

public function renameColumn($table, $name, $newName)
{
    throw new CDbException(Yii::t('yii', 'Renaming a DB column is not supported by SQLite.'));
}

public function renameTable($table, $newName)
{
    return 'ALTER TABLE ' . $this->quoteTableName($table) . ' RENAME TO ' . $this->quoteTableName($newName);
}

public function resetSequence($table,$value=null)
{
    if($table->sequenceName===null)
        return;
    if($value!==null)
        $value=(int)($value)-1;
    else
        $value=(int)$this->getDbConnection()
            ->createCommand("SELECT MAX(`{$table->primaryKey}`) FROM {$table->rawName}")
            ->queryScalar();
    try
    {
        // it's possible that 'sqlite_sequence' does not exist
        $this->getDbConnection()
            ->createCommand("UPDATE sqlite_sequence SET seq='$value' WHERE name='{$table->name}'")
            ->execute();
    }
    catch(Exception $e)
    {
    }
}

public function truncateTable($table)
{
    return "DELETE FROM ".$this->quoteTableName($table);
}