framework/db/mssql/Schema.php
protected function findPrimaryKeys($table)
    {
        $result = [];
        foreach ($this->findTableConstraints($table, 'PRIMARY KEY') as $row) {
            $result[] = $row['field_name'];
        }
        $table->primaryKey = $result;
    }
protected function findPrimaryKeys($table)
    {
        $result = [];
        foreach ($this->findTableConstraints($table, 'PRIMARY KEY') as $row) {
            $result[] = $row['field_name'];
        }
        $table->primaryKey = $result;
    }
Collects the primary key column details for the given table.
@param TableSchema $table the table metadata