src/Soluble/Normalist/Driver/Metadata/NormalistModels.php
public function getPrimaryKey($table)
    {
        $this->checkTableArgument($table);
        $pks = $this->getPrimaryKeys($table);
        if (count($pks) > 1) {
            $keys = implode(',', $pks);
            throw new Exception\MultiplePrimaryKeyException(__METHOD__ . ". Multiple primary keys found on table '$table':  $keys");
        }
        return $pks[0];
    }
public function getPrimaryKey($table)
    {
        $this->checkTableArgument($table);
        $pks = $this->getPrimaryKeys($table);
        if (count($pks) > 1) {
            $keys = implode(',', $pks);
            throw new Exception\MultiplePrimaryKeyException(__METHOD__ . ". Multiple primary keys found on table '$table':  $keys");
        }
        return $pks[0];
    }
Return unique table primary key

@throws Exception\InvalidArgumentException
@throws Exception\ErrorException
@throws Exception\NoPrimaryKeyException when no pk
@throws Exception\MultiplePrimaryKeyException when multiple pk found
@throws Exception\ExceptionInterface
@throws Exception\TableNotFoundException

@param string $table
@return string|int primary key