DNAMES: column_list returns an empty string if at least one column has a symbolic name

select column_list(column_create('a', 'val1'));

# +-----------------------------------------+

# | column_list(column_create('a', 'val1')) |

# +-----------------------------------------+

# |                                         |

# +-----------------------------------------+

# 1 row in set (0.00 sec)

select length(column_list(column_create('a', 'val1')));

# +-------------------------------------------------+

# | length(column_list(column_create('a', 'val1'))) |

# +-------------------------------------------------+

# |                                               0 |

# +-------------------------------------------------+

# 1 row in set (0.00 sec)

select column_list(column_create(1, 'val1'));

# +---------------------------------------+

# | column_list(column_create(1, 'val1')) |

# +---------------------------------------+

# | `1`                                   |

# +---------------------------------------+

# 1 row in set (0.00 sec)

select length(column_list(column_create(1, 'val1')));

# +-----------------------------------------------+

# | length(column_list(column_create(1, 'val1'))) |

# +-----------------------------------------------+

# |                                             3 |

# +-----------------------------------------------+

# 1 row in set (0.00 sec)

revision-id: elenst@ubuntu11.home-20120813090607-jtuq5p0umts16h5h

date: 2012-08-13 13:06:07 +0400

build-date: 2012-08-16 04:26:14 +0400

revno: 3490