15 calls to db_add_column() in Drupal 4

system_update_129 in database/updates.inc

system_update_133 in database/updates.inc

system_update_139 in database/updates.inc

system_update_145 in database/updates.inc

system_update_146 in database/updates.inc

system_update_148 in database/updates.inc

system_update_149 in database/updates.inc

system_update_153 in database/updates.inc

system_update_154 in database/updates.inc

system_update_158 in database/updates.inc

system_update_181 in database/updates.inc

update_fix_schema_version in ./update.php

If the schema version for Drupal core is stored in the variables table (4.6.x and earlier) move it to the schema_version column of the system table.

update_fix_sessions in ./update.php

System update 130 changes the sessions table, which breaks the update script's ability to use session variables. This changes the table appropriately.

update_fix_system_table in ./update.php

update_fix_watchdog in ./update.php

System update 142 changes the watchdog table, which breaks the update script's ability to use logging. This changes the table appropriately.