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78 lines
2.9 KiB
78 lines
2.9 KiB
3 years ago
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---
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title: "Link To Another Record"
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description: "Link To Another Record"
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position: 540
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category: "Product"
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menuTitle: "Link To Another Record"
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---
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### Relationship types:
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- One to one
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- A Table record in first table is related to only one record of second table.
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- Example: Country has a capital city
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- One to many
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- A Table record in first table is related to more than one record of second table. But second table record maps to only one entry of first table
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- NocoDB refers to this category of relationship as **has many**
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- For every **has many** relation defined, NocoDB augments **belongs to** relationship column in the other table automatically
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- Example: Country **has many** Cities. (other way mapping > City **belongs to** Country )
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- Many to many
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- A Table record in first table is related to more than one record of second table; second table record can also map to more than on record of first table.
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- NocoDB refers to this category of relationship as **many to many**
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- For every **many to many** relation defined between tables, NocoDB augments **many to many** relationship column in the other table automatically
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- Example: Film **has many** Actors. Actor **has many** Films (works on many films)
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Further details of relationship types can be found [here](https://afteracademy.com/blog/what-are-the-different-types-of-relationships-in-dbms)
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Relationships between table records can be established by using **LinkToAnotherRecord** column type.
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Workflow details are captured below
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## Adding a relationship
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### 1. Create column
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Click on '+' button at end of column headers
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### 2. Update column name
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Input name in the text box provided
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### 3. Select column type
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Select Column type as "LinkToAnotherRecord" from the drop-down menu
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### 4. Choose relationship type
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'Has Many': corresponds to the 'One-to-many' relationships
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'Many To Many': corresponds to the 'Many-to-many' relationships
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### 5. Select child table from drop down menu
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### 6. Click on 'Save'
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A new column will get created in both the parent table & child table
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## Updating linked records
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### 1. Open link record tab
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Click on the '+' icon in corresponding row - cell
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### 2. Select from the option displayed
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Use 'Filter box' to narrow down on search items
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You can opt to insert a new record as well, using "+ New Record" button
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### 3. Column mapping showing "Has Many" relationship
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Country 'has many' City
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### 4. Column mapping for "Belongs to" relationship [Automatically updated]
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City 'belongs to' Country
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