Source: https://dev-docs.nebula-graph.io/v5.3.2/database-gql-reference/fe/expressions/constant/
Documentation version: v5.3.2

# Constant value expression

The constant value expression holds a constant literal that refers to a fixed value that is used directly in a query and does not change during operations.

## Syntax

diagramsource

 constant_value_expression  

````
constant_value_expression ::=
    literal

````

## Parameters

### `literal`

The constant literal. `literal` supports literals of multiple data types as shown below.

- Numeric literal
- Boolean literal
- Character string literal
- Temporal literal
- List literal
- Record literal
- Vector literal
- Null

For more information, see [Data types](https://dev-docs.nebula-graph.io/v5.3.2/database-gql-reference/data-types/) and [Literals](https://dev-docs.nebula-graph.io/v5.3.2/database-gql-reference/fe/literals/).

## Examples

````
'''
RETURN 
1 AS num1, 
3.4 AS num2, 
true AS bool1, 
"str literal" AS str1, 
DATE '2024-01-01' AS temporal1, 
DURATION ({years:1, months:2}) AS duration1, 
LIST [2,3,4] AS list1, 
{a:1, b:true, c:"str literal"} AS record1, 
VECTOR<3, FLOAT>([1.0, 2.0, 3.0]) AS v1, 
NULL AS null1
'''

````

Return:

````
+------+------+-------+-------------+------------+-----------+---------+------------------------------+---------------+-------+
| num1 | num2 | bool1 | str1        | temporal1  | duration1 | list1   | record1                      | v1            | null1 |
+------+------+-------+-------------+------------+-----------+---------+------------------------------+---------------+-------+
| 1    | 3.4  | true  | str literal | 2024-01-01 | P1Y2M     | [2,3,4] | {a:1,b:true,c:"str literal"} | [1.0,2.0,3.0] | null  |
+------+------+-------+-------------+------------+-----------+---------+------------------------------+---------------+-------+

````