Merge pull request #5472 from metabase/0.25-docs

0.25 docs: nested queries and custom user projections

docs/administration-guide/03-metadata-editing.md

@@ -74,6 +74,24 @@ This is also where you set mark special fields in a table:
 * Entity Name — different from the entity key, this is the field whose heading represents what each row in the table *is*. For example, in a Users table, the User column might be the entity name.
 * Foreign Key — this is a field in this table that uniquely identifies a *row* in another table. In other words, this is a field that, almost always, points to the primary key of another table. For example, in a Products table, you might have a Customer ID field that points to a Customers table, where Customer ID is the primary key.
 
+### Remapping field values
+One thing that happens commonly in tables is that you'll have a foreign key field, like `Product ID`, with a bunch of ID values in it, when what you actually want to see most of the time is the entity name, like the `Product Title`. You might also have fields which contain coded values that you'd prefer to show up as translated or readable values in your tables and charts — like changing `0`, `1`, and `2` to `Female`, `Male`, and `Other` for example.
+
+To do this in Metabase, click on the gear icon to the right of a field's Type dropdown in the Data Model section of the Admin Panel. You'll see a form with these options:
+
+![Remapping form](./images/remapping/form.png)
+
+`Visibility` and `Type` are the same as on the main Data Model page, but `Display values` lets you choose to swap out a field's values with something else.
+
+Foreign key remapping lets you swap out a foreign key's values with the values of any other field in the connected table. In this example, we're swapping out the `Product ID` field's values with the values in the `Title` field in the Product table:
+
+![Remapping form](./images/remapping/fk-mapping.png)
+
+Another option is custom remapping, which is currently only possible for numeric fields. This lets you map every number that occurs in this field to either a different numeric value or even to a text value, like in this example:
+
+![Remapping form](./images/remapping/custom-mapping.png)
+
+
 ---
 
 ## Next: managing users

docs/users-guide/04-asking-questions.md

 
-## Asking Questions
+## Asking questions
 ---
-Metabase's two core concepts are questions and their corresponding answers. Everything else is based around questions and answers. To ask Metabase a question, click the New Question button at the top of the screen to go to the question builder.  
+Metabase's two core concepts are questions and their corresponding answers. Everything else is based around questions and answers. To ask Metabase a question, click the New Question button at the top of the screen to go to the question builder. (Note: to [create a new SQL query](04-asking-questions.html#using-sql), click the console icon in the top right of the new question screen.)
 
 ![queryinterfacebar](images/QueryInterfaceBar.png)
 
 Questions are made up of a number of parts: source data, filters, and answer output.
 
-### Source Data
+### Source data
 ---
-All of the data in databases are in tables. Typically, tables will be named for the thing that each row in the table contains. For example, in a Customers table, each row in the table would represent a single customer. This means that when you’re thinking about how to phrase your question, you’ll need to decide what your question is about, and which table has that information in it. The first dropdown menu in the question builder is where you’ll choose the table you want.  
+All of the data in databases are in tables. Typically, tables will be named for the thing that each row in the table contains. For example, in a Customers table, each row in the table would represent a single customer. This means that when you’re thinking about how to phrase your question, you’ll need to decide what your question is about, and which table has that information in it.
+
+The first dropdown menu in the question builder is where you’ll choose the database and table you want.
+
+#### Using saved questions as source data
+
+If you've [saved some questions](06-sharing-answers.html), in the Data menu you'll see the option to use one of your saved questions as source data. What this means in practice is that you can do things like use complex SQL queries to create new tables that can be used in a question just like any other table in your database.
+
+You can use any saved question as source data, provided you have [permission](../administration-guide/05-setting-permissions.html) to view that question. You can even use questions that were saved as a chart rather than a table. The only caveat is that you can't use a saved question which itself uses a saved question as source data. (That's more inception than Metabase can handle!)
 
 ### Filters
 ---
@@ -47,7 +55,7 @@ Now the relative date will be referencing the past 30 days from *today*, *not* f
 #### Using segments
 If your Metabase admins have created special named filters, called segments, for the table you’re viewing, they’ll appear at the top of the filter dropdown in purple text with a star next to them. These are shortcuts to sets of filters that are commonly used in your organization. They might be something like “Active Users,” or “Most Popular Products.”
 
-### Answer Output
+### Answer output
 ---
 The last section of the question builder is where you select what you want the output of your answer to be, under the View dropdown. You’re basically telling Metabase, “I want to view the…” Metabase can output the answer to your question in four different ways: