# \$1\$1 (Concatenation) operator
<a name="concat_op"></a>

Concatenates two expressions on either side of the \$1\$1 symbol and returns the concatenated expression. 

The concatentation operator is similar to [CONCAT function](CONCAT.md). 

**Note**  
For both the CONCAT function and the concatenation operator, if one or both expressions is null, the result of the concatenation is null. 

## Syntax
<a name="concat_op-synopsis"></a>

```
expression1 || expression2
```

## Arguments
<a name="concat_op-arguments"></a>

 *expression1*, *expression2*   
Both arguments can be fixed-length or variable-length character strings or expressions. 

## Return type
<a name="concat_op-return-type"></a>

 The \$1\$1 operator returns a string. The type of string is the same as the input arguments. 

## Example
<a name="concat_op-example"></a>

The following example concatenates the FIRSTNAME and LASTNAME fields from the USERS table: 

```
select firstname || ' ' || lastname
from users
order by 1
limit 10;

concat
-----------------
Aaron Banks
Aaron Booth
Aaron Browning
Aaron Burnett
Aaron Casey
Aaron Cash
Aaron Castro
Aaron Dickerson
Aaron Dixon
Aaron Dotson
(10 rows)
```

 To concatenate columns that might contain nulls, use the [NVL and COALESCE functions](NVL_function.md) expression. The following example uses NVL to return a 0 whenever NULL is encountered. 

```
select venuename || ' seats ' || nvl(venueseats, 0) 
from venue where venuestate = 'NV' or venuestate = 'NC'
order by 1
limit 10;

seating                            
-----------------------------------
Ballys Hotel seats 0               
Bank of America Stadium seats 73298
Bellagio Hotel seats 0             
Caesars Palace seats 0             
Harrahs Hotel seats 0              
Hilton Hotel seats 0               
Luxor Hotel seats 0                
Mandalay Bay Hotel seats 0         
Mirage Hotel seats 0               
New York New York seats 0
```