After a `create index` query on a table with foreign keys, the foreign
keys are either lost or made inconsistent. But the same query using
`alter table` runs without causing any problems. This is due to the
difference in the type of sql_command values these queries are mapped
to. The create index query's value, SQLCOM_CREATE_INDEX is not handled
properly along with the SQLCOM_ALTER_TABLE command. This causes the
above said problem. This patch fixes that by additionally also handling
SQLCOM_CREATE_INDEX wherever SQLCOM_ALTER_TABLE/SQLCOM_DROP_INDEX are
handled.