> ## Documentation Index
> Fetch the complete documentation index at: https://docs.activeviam.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Overrides with DirectQuery
export const productName = "Atoti FRTB";
This section explains how to define overrides in {productName} using DirectQuery and also how to modify the relevant database tables.
Overrides allow for shifting data for a specific parameter set into a specific location.
There are two steps to defining overrides with DirectQuery:
1. Define the override in the override table.
2. Add the new override members to the base table.
## Step 1: Define override in the override Table
Simply add a row in the override table.
## Step 2: Add the new override member to the Base Table
Next, add data into the override table's base table. Details are in the ***Override Base Table*** section for each
override table in the [Database](../../../database/standardisedapproach/overrides/index) chapter.
Ensure the following:
* ***shift members*** exist in the base table, otherwise Atoti will not be able to shift the data as it cannot see the *shift member* of the
***shift member***'s hierarchy.
* The ***OVERRIDE KEY FIELD*** field of the base table is populated with a custom string in the format: "**`memberToShift::memberValue`**".\
The ***memberToShift*** and ***memberValue*** come from the override's definition.
## Example
This example is based on the reference override defined in the input file:
`sample-data/data/2018-09-28/Sensitivities/samples/Underlying_Desc_Overrides.csv`
In this example we perform the following steps:
1. Define the override.
2. Populate the [Underlying Description Overrides](../../../input-files/underlying-description-overrides) table.
3. Populate the override base [Underlying Description](../../../database/underlying_description) table.
### Define the Override
Here is a simple example where we want to shift our **"Carbon Emissions Trading"** *Underlying* of the **"Commodity"** *RiskClass* into *Bucket* **"3a"** for the **"CRR3"**
*Parameter Set*.
Our desired override is thus as follows:
| Underlying | Risk Class | ParameterSet | Bucket |
| ------------------------ | ---------- | ------------ | ------ |
| Carbon Emissions Trading | Commodity | CRR3 | 3a |
### Populate the Override Table
We first start by defining the override in the appropriate override table. For this example we are defining the override in the
[Underlying Description Override](../../../input-files/underlying-description-overrides) table. We also need to define an *AsOfDate* that the override is
effective for. Here we use an *AsOfDate* of *`"2018-09-28"`* (the latest date in the provided reference data).
Our table contains the following data (table is transposed for readability due to the large number of columns):
| Underlying Description Overrides Field | Not Null | Value |
| -------------------------------------- | -------- | ------------------------ |
| **UNDERLYING** | Yes | Carbon Emissions Trading |
| **RISK\_CLASS** | Yes | Commodity |
| **PARAMETER\_SET** | Yes | CRR3 |
| **BUCKET** | | 3a |
| **CSRQUALITY** | | |
| **CSRSECTOR** | | |
| **CSRRATING** | | |
| **EQUITY\_MARKET\_CAP** | | |
| **EQUITY\_ECONOMY** | | |
| **EQUITY\_SECTOR** | | |
| **POOL** | | |
| **ATTACHMENT** | | |
| **DETACHMENT** | | |
| **AS\_OF\_DATE** | Yes | 2018-09-28 |
### Populate the Override Base Table
We now inject some data into the override table's base table. We can find the base table in the
[Override Base Table](../../../input-files/underlying-description-overrides#override-base-table) section for the Underlying Description Overrides.\
The base table is the [Underlying Description](../../../database/underlying_description) table.
The members we want to shift our override into have to exist in the base table, otherwise Atoti will not be able to shift the data.
We can make Atoti aware of our new member by adding the new member to the base table.
We must generate an entry in the [Underlying Description](../../../database/underlying_description) table in the following sequence:
* Define the [Override Parameters](../../../input-files/underlying-description-overrides#override-parameters) fields from the base store.
* Create the [Override Tuples](../../../input-files/underlying-description-overrides#create-base-store-tuples).
* Map the override tuples back to the base table using the [Override Fields to Base Table Fields Mapping](../../../input-files/underlying-description-overrides#map-override-fields-to-base-table-fields).
#### Define Override Parameters Base Table Fields
For Underlying Description overrides our parameter fields can be found in
[Override Parameters](../../../input-files/underlying-description-overrides#override-parameters):
| Override Parameter | **Underlying Description** Field |
| ----------------------- | -------------------------------- |
| **OVERRIDE KEY FIELD** | **UNDERLYING** |
| **OVERRIDE DATE FIELD** | **AS\_OF\_DATE** |
#### Create the Override Tuples
We can see in the [Create Base Store Tuples](../../../input-files/underlying-description-overrides#create-base-store-tuples)
section that the following fields are the override's fields to create tuples for:
| Underlying Description Override Field |
| ------------------------------------- |
| **PARAMETER\_SET** |
| **BUCKET** |
| **CSRQUALITY** |
| **CSRSECTOR** |
| **CSRRATING** |
| **EQUITY\_MARKET\_CAP** |
| **EQUITY\_ECONOMY** |
| **EQUITY\_SECTOR** |
| **POOL** |
| **ATTACHMENT** |
| **DETACHMENT** |
We can define the override tuples by going through each field in our override definition:
| Field | Tuple to generate |
| ---------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------- |
| UNDERLYING
RISK\_CLASS
| These do not exist in the Underlying Description override Fields, so we can skip them. |
| [PARAMETER\_SET](#parameter_set) | See below. |
| [BUCKET](#bucket) | See below. |
| CSRQUALITY
CSRSECTOR
CSRRATING
EQUITY\_MARKET\_CAP
EQUITY\_ECONOMY
EQUITY\_SECTOR
POOL
ATTACHMENT
DETACHMENT | These are not defined, so we can skip them. |
| AS\_OF\_DATE | Does not exist in the Underlying Description override Fields, so we can skip it. |
##### PARAMETER\_SET
The ParameterSet field does exist in the Underlying Description override Fields, so we generate the following tuple:
| Underlying Description Override Field | Value |
| ------------------------------------- | ------------------ |
| OVERRIDE KEY FIELD | ParameterSet::CRR3 |
| OVERRIDE DATE FIELD | |
| ParameterSet | CRR3 |
| Bucket | |
| CSRQuality | |
| CSRRating | |
| EquityMarketCap | |
| EquityEconomy | |
| EquitySector | |
| Pool | |
| Attachment | |
| Detachment | |
| CSRSector | |
##### BUCKET
The Bucket field does exist in the Underlying Description override Fields, so we generate the following tuple:
| Underlying Description Override Field | Underlying Description Field | Note |
| ------------------------------------- | ---------------------------- | ----------------- |
| OVERRIDE KEY FIELD | UNDERLYING | |
| OVERRIDE DATE FIELD | AS\_OF\_DATE | |
| PARAMETER\_SET | | No mapping exists |
| BUCKET | BUCKET | |
| CSRQUALITY | CSRQUALITY | |
| CSRSECTOR | CSRSECTOR | |
| CSRRATING | CSRRATING | |
| EQUITY\_MARKET\_CAP | EQUITY\_MARKET\_CAP | |
| EQUITY\_ECONOMY | EQUITY\_ECONOMY | |
| EQUITY\_SECTOR | EQUITY\_SECTOR | |
| POOL | POOL | |
| ATTACHMENT | ATTACHMENT | |
| DETACHMENT | DETACHMENT | |
| | RISK\_CLASS | No mapping exists |
| | GIRR\_CURVE\_TYPE | No mapping exists |
| | GIRR\_CCY | No mapping exists |
| | UNDERLYING\_FXORIGINAL\_CCY | No mapping exists |
#### Map Override Tuples to Base Table
We can now [map the override tuples to base table entries](../../../input-files/underlying-description-overrides#map-override-fields-to-base-table-fields).
We use the following to map the override tuples back to the *Underlying Description* table:
There is no mapping for the **ParameterSet** field
| Underlying Description Override Field | Underlying Description Field | Note |
| ------------------------------------- | ---------------------------- | ----------------- |
| OVERRIDE KEY FIELD | UNDERLYING | |
| OVERRIDE DATE FIELD | AS\_OF\_DATE | |
| PARAMETER\_SET | | No mapping exists |
| BUCKET | BUCKET | |
| CSRQUALITY | CSRQUALITY | |
| CSRSECTOR | CSRSECTOR | |
| CSRRATING | CSRRATING | |
| EQUITY\_MARKET\_CAP | EQUITY\_MARKET\_CAP | |
| EQUITY\_ECONOMY | EQUITY\_ECONOMY | |
| EQUITY\_SECTOR | EQUITY\_SECTOR | |
| POOL | POOL | |
| ATTACHMENT | ATTACHMENT | |
| DETACHMENT | DETACHMENT | |
| | RISK\_CLASS | No mapping exists |
| | GIRR\_CURVE\_TYPE | No mapping exists |
| | GIRR\_CCY | No mapping exists |
| | UNDERLYING\_FXORIGINAL\_CCY | No mapping exists |
By using the above mapping we generate the following entries for the Underlying Description table. We use "N/A" for the **RISK\_CLASS** as it is a
non-nullable field:
| Underlying Description Field | Not Null | Entry 1 | Entry 2 |
| ---------------------------- | -------- | ------------------ | ---------- |
| AS\_OF\_DATE | Y | 2018-09-28 | 2018-09-28 |
| UNDERLYING | Y | ParameterSet::CRR3 | Bucket::3a |
| RISK\_CLASS | Y | “N/A” | “N/A” |
| BUCKET | | | 3a |
| GIRR\_CURVE\_TYPE | | | |
| GIRR\_CCY | | | |
| CSRQUALITY | | | |
| CSRSECTOR | | | |
| CSRRATING | | | |
| EQUITY\_MARKET\_CAP | | | |
| EQUITY\_ECONOMY | | | |
| EQUITY\_SECTOR | | | |
| POOL | | | |
| ATTACHMENT | | | |
| DETACHMENT | | | |
| UNDERLYING\_FXORIGINAL\_CCY | | | |