Columns View
The Venn Set Column view allows you to specify precisely which columns you would like returned in your Venn Set for each of the individual Queryable Items to be merged in the Venn Set. This allows you to ensure each Queryable Item has the same data structure, before being merged, in an intuitive and easy to follow way.
Venn Set Column Features
The columns displayed here are the actual columns that will be returned by your resulting query. Each Queryable Item must have the same number, and type, of columns defined so the overall merged set of data all conform to the same shape.
Caution
Columns are defined against the currently selected Queryable Item, and the column defined for the first Queryable Item dictate the columns, and type, that all other Queryable Items in this Venn Set must also have. For instance if you have the Users entity and the Teams entity in a Venn Set, and want to merge them in to a combined list of user and team names, then you would add the Name from the User entity as a column first. You would then need to add the Name for the Team entity as a column too, so both entities have the same columns being returned and can be merged together.
The columns specified for the first Queryable Item here are directly the columns that will be visible in the SQL Wrapper itself [see here for more info]. This is because by definition all the other Queryable Items must have the same number, and type, of columns defined too in order for the data to be combined correctly. All of these columns then construct the shape of the data returned by this Venn Set. Most importantly the system completely understands all aspects of the parameters, query and return columns so the venn set can be completely integrated into the platform as if it's a standard created view.
Important
It's important to note that the names provided by the first Queryable Item will be the names returned by the actual SQL Wrapper itself when executing this query. The other Queryable Items may have the same columns and structure, but may also have different names. The names defined on those columns are ignored as only the ones used from the first Queryable Item are used, as all the data is merged into one set anyway.
Columns can also have column properties, behaviour properties (such as aggregate options), and grid display properties.
You can also create custom calculation columns that perform custom sql you want embedded in the calculation.
Creating Venn Set Columns
Whenever you have a Queryable Item selected you will be able to use the "New SQL Type Wrapper" command to add fields from that QueryableItem to the columns of this dataset.
When you click the command (only available if you have a Queryable Item selected) the system will popup a dialog box listing all the available fields within that Queryable Item. You can multi-select as many fields as you would like to add and hit Ok. The system will automatically add all those fields as columns to the dataset in the correct order.
Note
It will also automatically configure the columns to have the correct type, and settings, depending on what the field you added is. For instance it will set up the Name, Entity Type, Entity Property Name, Enum Property Name, SQL Type and other properties for you.
This makes it incredibly easy to just add the fields you want from the QueryableItems you have selected into the set of column results.
Custom Calculations
You can also create custom calculation fields. To do this you can select 
Add Calculated Field, instead of new sql type wrapper.
This will create a new column that doesn't have fields auto-populated. You will need to specify the name, any entity type/property relationships, and the SQL Type (defaults to nvarchar(50)).
You can then select the 
Edit Calculation command when you have that column selected. This will popup a sql editor that allows you to enter any custom sql for this column that you like.
Important
You can refer to any other column in your sql using the format {ColumnName}. So for instance if you have two columns called TotalA and TotalB you can create a custom sql calculation field with the sql being:
IsNull({TotalA}, 0.0) + IsNull({TotalB}, 0.0)
Which will sum both columns together to give you a grand total.
Warning
You must make sure that the sql you enter has a return type that matches the type you specified for the column itself. If it doesn't your dataset will fail to return results and will throw an error.
It's important to note that this functionality is also restricted and certain keywords if used (such as 'drop', etc) will result in an error and the dataset will fail to run. You should restrict this functionality to only the root account with the correct permissions.
Venn Set Column Properties
The columns of a venn set, are the same as the columns of a SQL Wrapper see here for more info, and have the following properties:
| Name | Description |
|---|---|
| [Unique] [Required] Name |
The name of this column. This is the name used as column headers in csv exports, and is the mnemonic you can use to refer to this columns value in custom sql formulas. |
| Column User Friendly Label | This is the column name the user sees when the results are displayed in a grid, or other presentation format. |
| [Key] Index |
The order this column will appear in the result set. This can be moved up and down using the standard grid commands. |
| Parent Index | This column is hidden by default but can be made visible to edit if needed. The parent index is used for columns that display labels for unique identifiers. If you have a column that holds a unique identifier key, you can set the label of that column to have a parent index of the uniqueidentifier column. The system will then know how to display the label in the grid for the user rather than a list of uniqueidentifiers the user won't be able to recognize. |
| Description | A user friendly description of this column |
| Visible | Indicates if this column is visible by default when the results are displayed in a grid. The user can always make the column visible if it is hidden, and will always see the column in result exports too. |
| Exclude From Result Set | Indicates this column is not actually to be included in the result set. Can be used to refer to the column itself in custom calculations but make sure it isn't included in the actual results as a column itself. |
| Aggregate | Indicates this column should have its results aggregated. Can be:
If this is anything but None, then all other columns that have an aggregate of None will be used as part of the Group By for the result set. |
| Has Custom Aggregate | Indicates this column has a custom calculation that applies a custom sql clr aggregate function to the results. Use the Edit Calculated Field command to edit the custom calculation to call your clr sql aggregate function. This refers to SQL Functions (which define the clr sql functions that can be used) and is only available as an option if the AllowCLRSQLFunctions flag in the GlobalEnv table is set to 1. All other non-aggregated columns will be set to group by in the result set just as they would if an Aggregate value other than None had been selected. |
| EntityType | The type of entity this column has data that originates from. |
| Entity Property Name | The property of the Queryable Item that this column is populated from |
| Enum Property Type | If this property is an enum type this holds the type of enum to be used for displaying in grids. |
| Format | Applies any custom formatting you want to the result when displayed in a grid. See here for more info. |
| Footer Aggregate | Indicates when displayed in a grid that this column should be totaled automatically and displayed on the grid itself. This will also happen when the data is arbitrarily grouped by the user. |
| Group Header | Indicates this column should belong to a header group when displayed in a grid |
| Sub Group Header | Indicates this column should belong to a sub header group within a group header when displayed in a grid |
| Group By | When displayed in a grid this indicates this column should automatically be grouped in the grid |
| Freeze Up To | By default the first column is frozen when displayed in a grid. Here you can specify a different column that should be frozen when scrolling through the grid horizontally. |
| Part Of Row Header | When scrolling vertically the scroll bar displays a row header quick view. This indicates if this column should be part of that template. |
| Is Default Search | Indicates when the user searches the grid that this column should be included in that search by default |
| SQL Type | Indicates the actual underlying sql type this column holds |
| Max Length | The max length to use if this column is a text type such as nvarchar. If blank it is the equivalent to nvarchar(max). |
| Precision | If this is a decimal sql type this holds the precision amount as in decimal(18,2) |
| Scale | If this is a decimal sql type this holds the scale amount as in decimal(18,2) |
Commands
Note
A Column has the standard set of commands and functions when being viewed from a grid. See our standard grid functionality.
Note
As a Column has a sequence the standard grid allows you to move the items up and down changing their order.
The Column grid also has the following custom commands:
- Add Calculated Field
Used to add a new calculated field to the set of result columns. Described in more detail above. - Edit Calculated Field
Used to edit the sql of a calculated field in the set of result columns. Described in more detail above.