analyze-tables should validate provide --column names

[simonw]

Noticed this while testing:

• No need to show common values if everything is null #547

If you pass a non-existent column to -c/--column you don't get an error message.

[simonw]

Oh, I see why that is now:

sqlite-utils/sqlite_utils/cli.py

Lines 2670 to 2679 in 6027f3e

	def _analyze(db, tables, columns, save, common_limit=10, no_most=False, no_least=False):
	if not tables:
	tables = db.table_names()
	todo = []
	table_counts = {}
	for table in tables:
	table_counts[table] = db[table].count
	for column in db[table].columns:
	if not columns or column.name in columns:
	todo.append((table, column.name))

This is because of the following command:

sqlite-utils analyze-tables table1 table2 --column x

Since you can pass multiple tables AND multiple columns, the tool currently assumes that the column(s) you specify may be available on a subset of the provided tables.

I'm going to change this so if the column is not on ANY of those tables you get an error.