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> For a complete documentation index, see https://ocient.ferndocs.com/llms.txt.
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# Other Functions and Expressions

> Access other functions and expressions for diverse data processing and analysis.

The Ocient® System supports these miscellaneous functions and expressions.

### CASE

`CASE` operates similarly to conditional scripting in other programming languages, allowing it to function like an if / then / else statement or as a switch statement.

`CASE` sets one or more `WHEN` conditions to be evaluated. When a condition is evaluated as true, the database applies the specified action in a `THEN` clause. If no matches are found, the database applies the action in the `ELSE` clause. If no `ELSE` clause is specified and no matches are found, the result is `NULL`.

This evaluation creates a new column where the values are expressions inside the `THEN` clause.

**Syntax**

```sql
--To use CASE like an if / then statement:

CASE <caseCondition> ELSE expression | NULL END

<caseCondition> ::=
WHEN search_condition | expression THEN expression | NULL

--To use CASE like a switch statement:
CASE switch_expression <switchCondition> ELSE expression | NULL END

<switchCondition> ::=
WHEN switch_value THEN expression | NULL
```

| **Arguments**       | **Description**                                                                            |
| ------------------- | ------------------------------------------------------------------------------------------ |
| `search_condition`  | A condition including a column name and a Boolean expression to evaluate.                  |
| `switch_expression` | A column name to be used to evaluate a `switch_value`.                                     |
| `switch_value`      | A value to be evaluated for the `switch_expression`.                                       |
| `expression`        | An expression to return based on evaluating the `search_condition` or `switch_expression`. |

**Example**

This example uses conditional logic with `CASE` to categorize individuals into different groups based on their ages.

```sql
SELECT age,
  CASE
    WHEN age < 13 THEN 'child'
    WHEN age < 19 THEN 'teen'
    ELSE 'adult'
  END AS age_grp
FROM sys.people
ORDER BY age;
```

**Example**

This example uses switch conditions to categorize age groups.

```sql
SELECT age,
  CASE age
    WHEN 13 THEN 'thirteen'
    WHEN 14 THEN 'fourteen'
    WHEN 15 THEN 'fifteen'
    WHEN 16 THEN 'sixteen'
    WHEN 17 THEN 'seventeen'
    WHEN 18 THEN 'eighteen'
    WHEN 19 THEN 'nineteen'
    ELSE 'not teens'
  END
FROM sys.people;
```

### COALESCE

Returns the first argument that is not NULL or NULL if all arguments are NULL. Arguments must be the same type, and the returned value is the most compatible type.

`COALESCE` can work with mixed-type numeric arguments, which means the lower precedence types are cast to the highest one. For example, when using `TIMESTAMP` and `DATE` data types, all values are cast to a timestamp.

**Syntax**

```sql
COALESCE(value1, value2 [,...])
```

| **Argument**   | **Data Type**                                                      | **Description**                                           |
| -------------- | ------------------------------------------------------------------ | --------------------------------------------------------- |
| `value [,...]` | All data types are supported. All values must be of the same type. | Values for comparison to find the value that is not NULL. |

**Example**

```sql
SELECT COALESCE(null,null,13,null,8);
```

Output: `13`

### COMMIT

Returns the most recent commit hash of the database to which the client is currently connected.

**Syntax**

```sql
COMMIT()
```

**Example**

```sql
SELECT COMMIT();
```

Output: `cd0d53e3aa`

### CURRENT_DATABASE

Alias for [**DATABASE**](#database).

### CURRENT_NODE

Returns the name of the SQL Node where the current query executes. The name of the node corresponds to the `name` column in the `sys.nodes` system catalog table.

**Syntax**

```sql
CURRENT_NODE()
```

**Example**

```sql
SELECT CURRENT_NODE();
```

Output: `sql0`

### CURRENT_GROUPS

Returns the fully qualified names of groups to which the current user belongs. You can query the `sys.groups` system catalog table to view the group information.

**Syntax**

```sql
CURRENT_GROUPS()
```

**Example**

```sql
SELECT CURRENT_GROUPS();
```

Output: `['sso_users@system', 'analysts@system']`

### CURRENT_NODE_ID

Returns the identifier of the SQL Node where the current query executes. The name of the node corresponds to the `id` column in the `sys.nodes` system catalog table.

**Syntax**

```sql
CURRENT_NODE_ID()
```

**Example**

```sql
SELECT CURRENT_NODE_ID();
```

Output: `f690c14a-4e4f-4143-8e5e-20c90b60e15c`

### CURRENT_SCHEMA

Returns the name of the current schema.

**Syntax**

```sql
CURRENT_SCHEMA()
```

**Example**

```sql
SELECT CURRENT_SCHEMA();
```

Output: `schema@database`

### CURRENT_SESSION_ID

Returns the identifier of the current session as a Universally Unique IDentifier (UUID) that matches the `id` column in the `sys.sessions` system catalog table.

**Syntax**

```sql
CURRENT_SESSION_ID()
```

**Example**

```sql
SELECT CURRENT_SESSION_ID();
```

Output: `6ffe8383-e894-44c0-91c5-38d5925f51ec`

### CURRENT_SYSTEM

Returns the name of the system. You can set the name using the [**ALTER SYSTEM RENAME TO**](/guides/sql-reference/data-definition-language-ddl-statement-reference/cluster-and-node-management) SQL statement.

> **Note**
>
> If you never set the system name, the Ocient System initializes the name of the system as a random identifier, the UUID.

**Syntax**

```sql
CURRENT_SYSTEM()
```

**Example**

```sql
SELECT CURRENT_SYSTEM();
```

Output: `2677b88c-7f07-470c-be3e-e1bafddc1221`

### CURRENT_USER

Returns the user for the current connection.

**Syntax**

```sql
CURRENT_USER()
```

**Example**

```sql
SELECT CURRENT_USER();
```

Output: `user@database`

### DATABASE

Alias for CURRENT_DATABASE.

Returns the name of the database to which the client is currently connected.

**Syntax**

```sql
DATABASE()
```

**Example**

```sql
SELECT DATABASE();
```

Output: `test`

### GREATEST

Returns the largest non-NULL value of all the arguments, or NULL if all the arguments are NULL. All values must be comparable to each other.

**Syntax**

```sql
GREATEST(value [,...])
```

| **Argument**   | **Data Type**                                                                                          | **Description**                                                     |
| -------------- | ------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------- |
| `value [,...]` | All data types are supported.  All values must either be of the same type or comparable to each other. | A series of values to compare to find the largest value of the set. |

**Example**

```sql
SELECT GREATEST(12,13,5,8);
```

Output: `13`

### IF_NULL

Returns the first argument that is not NULL or NULL if all arguments are NULL. Arguments must be the same type, and the returned value is the most compatible type.

`IF_NULL` can work with mixed-type numeric arguments, which means the lower precedence types are cast to the highest one. For example, when using `TIMESTAMP` and `DATE` data types, all values are cast to a timestamp.

**Syntax**

```sql
IF_NULL(value1, value2)
```

| **Argument**   | **Data Type**                                                      | **Description**                                           |
| -------------- | ------------------------------------------------------------------ | --------------------------------------------------------- |
| `value [,...]` | All data types are supported. All values must be of the same type. | Values for comparison to find the value that is not NULL. |

**Example**

```sql
SELECT IF_NULL(null, 5)
```

Output: `5`

### LEAST

Returns the smallest non-NULL value of all arguments, or NULL if all arguments are NULL. All values must be comparable to each other.

**Syntax**

```sql
LEAST(value [,...])
```

| **Argument**   | **Data Type**                                                                                          | **Description**                                                      |
| -------------- | ------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------- |
| `value [,...]` | All data types are supported.  All values must either be of the same type or comparable to each other. | A series of values to compare to find the smallest value of the set. |

**Example**

```sql
SELECT LEAST(12,13,5,8);
```

Output: `5`

### MURMUR3

Returns a 32-bit [**MurmurHash3 hash**](https://github.com/aappleby/smhasher/blob/master/README.md) of the input value as an INTEGER data type. If you specify a NULL input value, the function returns 0. This function is primarily useful for partitioning data.

**Syntax**

```sql
MURMUR3(value)
```

| **Argument** | **Data Type**                     | **Description**                                    |
| ------------ | --------------------------------- | -------------------------------------------------- |
| `value`      | All SQL data types are supported. | Specified value for the MurmurHash3 hash function. |

**Example**

```sql
SELECT MURMUR3(null);
```

Output: `0`

**Example**

```sql
SELECT MURMUR3('fred');
```

Output: `331477181`

### **NULL_IF**

Returns the NULL value if two arguments are equal; otherwise, returns the first argument.

**Syntax**

```sql
NULL_IF(value1, value2)
```

**Example**

```sql
SELECT NULL_IF(13,12);
```

Output: `13`

**Example**

```sql
SELECT NULL_IF(13,13);
```

Output: `NULL`

### RAND_UUID

Alias for [**UUID_GENERATE**](#uuidgenerate).

### SHOW

The `SHOW` function lets you explore the database and its metadata for user-defined items. For details, see [**Information Schema**](/guides/sql-reference/system-catalog-reference/information-schema).

**Syntax**

```sql
SHOW <item>;

-- <item> can be any of the following:
{   COLUMNS,
    DATA_TYPES,
    DATABASES,
    GROUPS,
    INDEXES,
    RESERVED_WORDS,
    SCHEMATA,
    TABLES,
    USERS,
    VIEWS }
```

**Examples**

This example uses SHOW to explore databases on the system.

```sql
SHOW DATABASES;
```

*Output*

```sql
database_name
created
--------------------------------------------------------------------------
test
2022-12-19 19:52:34.576426348
```

This example explores table data.

```sql
SHOW TABLES;
```

*Output*

```sql
table_catalog
table_schema
table_name
table_type
is_insertable_into
created_at
--------------------------------------------------------------------------
test
test_schema
test_table
BASE TABLE
YES
2022-12-20 14:45:13.858144104
```

### UUID_GENERATE

Alias for [**RAND_UUID**](#randuuid).

Generates a random UUID value (version 4).

For details about the UUID data type, see [**Data Types**](/guides/sql-reference/data-types).

**Syntax**

```sql
UUID_GENERATE()
```

**Example**

Generate one UUID value.

```sql
SELECT UUID_GENERATE();
```

Output: `3f6b2b58-4c9a-4a32-9b6a-b2f9b8e2a41e`

### TYPE_STRIP

Returns the SQL type of the specified value.

**Syntax**

```sql
TYPE_STRIP(value)
```

| **Argument** | **Data Type**                 | **Description**                                                                                        |
| ------------ | ----------------------------- | ------------------------------------------------------------------------------------------------------ |
| `value`      | All data types are supported. | Specified value for the determination of the type. You can specify columns, literals, and expressions. |

**Examples**

```sql
SELECT TYPE_STRIP(_R{1,2,3});
```

Output: `MATRIX[1][3]`

```sql
SELECT TYPE_STRIP(current_user());
```

Output: `CHAR`

```sql
SELECT TYPE_STRIP(NULL);
```

Output: `NULL`

```sql
SELECT TYPE_STRIP(NULL::INT[]);
```

Output: `INT[]`

### VERSION

Returns the version of the database to which the client is currently connected.

**Syntax**

```sql
VERSION()
```

**Example**

```sql
SELECT VERSION();
```

Output: `22.0.0-20230105.2353`

### ZN

If `x` is NULL, returns 0. Otherwise, returns `x`.

**Syntax**

```sql
ZN(x)
```

**Example**

```sql
SELECT ZN(null);
```

Output: `0`

**Example**

```sql
SELECT ZN(12);
```

Output: `12`

## Related Links

[**Databases**](/guides/sql-reference/data-definition-language-ddl-statement-reference/databases)

[**System Catalog**](https://docs.ocient.com/system-catalog)

[**Database Administration**](/guides/database-administration)