> For the complete documentation index, see [llms.txt](https://docs.cloud.hoverfly.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cloud.hoverfly.io/create-simulations/using-data-sources-in-simulations/querying-data-sources.md).

# Querying data sources

### Reading from a CSV Data Source

You can read data from a CSV data source in a number of ways.

For illustration we will use this data source called "pets":

| id   | category | name    | status    |
| ---- | -------- | ------- | --------- |
| 1000 | birds    | Archie  | available |
| 1001 | dogs     | Zipper  | available |
| 1002 | dogs     | Teddy   | sold      |
| \*   | no data  | no data | no data   |

### Single value lookup with {{csv}}

The most basic query function is to return the value of one field (selected-column) given a field name to search (column-name) and a value to search for in that field (query-value). Of course the query-value would normally be pulled from the request.

Syntax:

```handlebars
{{csv 'data-source-name' 'column-name' 'query-value' 'selected-column' }}
```

Template Example: Display the Name of the pet with Id 1001

```handlebars
{{ csv 'pets' 'id' '1001' 'name' }}
```

Output:

```
Zipper
```

### More advanced examples: Single value lookup with {{csv}}

Template Example: Display the Name of the pet with Id taken from position 2 on the path

```handlebars
{{csv 'pets' 'id' 'Request.Path.[2]' 'name'}}
```

Template Example: Use conditional logic to check if a pet with Id taken from position 2 on the path exists, and if not return an error. Note that when the csv function is used within an #equal block, it needs to be enclosed in round brackets.

```handlebars
{{#equal (csv 'pets' 'id' 'Request.Path.[2]' 'name') 'no data'}}
    {{setStatusCode 404}}
{{else}}
.
.
{{/equal}}
```

###

### Retrieve all rows as a map with {{csvAsMap}}

Additional functions are available to query the CSV data source to return all or a filtered subset of it’s rows, as a map.

Retrieving the results as a map makes it simple to render back into the template, as you can use the {{this}} expression with the column names to identify which fields you want to render.

Note that as you will use this wrapped within an #each or #first block, the csvAsMap function must be enclosed inside round brackets.

See examples below.

Syntax:

```handlebars
{{csvAsMap 'data-source-name' }}
```

Template Example:

```handlebars
{
    "All-The-Pets": [ 
    {{#each (csvAsMap 'pets')}}
    {
        "id":{{this.id}}, 
        "category":"{{this.category}}", 
        "name":"{{this.name}}", 
        "status":"{{this.status}}"
    }
    {{#unless @last}},{{/unless}} 
    {{/each}} 
    ]
}
```

Output:

```json
{
    "All-The-Pets": [
        {
            "id": 1000,
            "category": "cats",
            "name": "Sylvester",
            "status": "available"
        },
        {
            "id": 1001,
            "category": "dogs",
            "name": "Zipper",
            "status": "available"
        },
        {
            "id": 1002,
            "category": "dogs",
            "name": "Teddy",
            "status": "sold"
        }
    ]
}
```

### Retrieve filtered rows as a map with {{csvMatchingRows}}

To filter the map on a single column value at the time of query you can use csvMatchingRows. This will return all the rows where the (column-name) = (query-value).

Note that as you will use this wrapped within an #each or #first block, the csvMatchingRows function must be enclosed inside round brackets.

```handlebars
{{csvMatchingRows 'data-source-name' 'column-name' 'query-value'}}
```

Template Example:

```handlebars
{
    "Dogs-Only": [ 
        {{#each (csvMatchingRows 'pets' 'category' 'dogs')}}
        {
            "id":{{this.id}}, 
            "category":"{{this.category}}", 
            "name":"{{this.name}}", 
            "status":"{{this.status}}"
        }
        {{#unless @last}},{{/unless}} {{/each}} 
        ]
}
```

Output:

```json
{
    "Dogs-Only": [
        {
            "id": 1001,
            "category": "dogs",
            "name": "Zipper",
            "status": "available"
        },
        {
            "id": 1002,
            "category": "dogs",
            "name": "Teddy",
            "status": "sold"
        }
    ]
}
```

### Advanced querying with SQL SELECT {{csvSqlCommand}}

A simplified SQL like syntax can be used to query the data in a csv data source and retrieve a map of the results. (This syntax can also be used to [UPDATE ](/create-simulations/using-data-sources-in-simulations/updating-data-in-data-sources.md)and [DELETE ](/create-simulations/using-data-sources-in-simulations/deleting-data-from-data-sources.md)from the data source. You cannot insert using this syntax however there is a mechanism which can be read about [here](/create-simulations/using-data-sources-in-simulations/inserting-data-into-a-data-source.md).)

Note that as you will use this wrapped within an #each or #first block, the csvSQLCommand must be enclosed inside round brackets.

You can read more about using this SQL like syntax [here](/create-simulations/using-data-sources-in-simulations/guidance-on-using-the-sql-like-syntax.md).

Syntax:

```handlebars
{{csvSqlCommand 'sql select, update or delete statement'}}
```

Template Example:

```handlebars
{
    "Dogs-With-Big-Ids-Only": [
    {{#each (csvSqlCommand "SELECT * FROM pets WHERE category = 'dogs' AND id >= '1002'")}}
        {
            "id":{{this.id}}, 
            "category":"{{this.category}}", 
            "name":"{{this.name}}", 
            "status":"{{this.status}}"
        }{{#unless @last}},{{/unless}}
    {{/each}}
    ]
}
```

Output:

```json
{
    "Dogs-With-Big-Ids-Only": [
        {
            "id": 1002,
            "category": "dogs",
            "name": "Violet",
            "status": "sold"
        }
    ]
}
```