---
title: Grammar Reference
sidebar_label: Grammar Reference
---

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This section describes grammar elements that are common to multiple SQL functions ([DDL](ddl.md), [Distribution Zones](distribution-zones.md), etc.).

## assign

{/* Railroad diagram omitted - see 3.1.0 docs */}

### Parameters

- `identifier` - the name of table, column or other element that will be updated by the operation.
- `expression` - a valid SQL expression that returns the values that must be assigned to the `identifier`.

Referenced by:

* MERGE
* UPDATE

## column_definition

{/* Railroad diagram omitted - see 3.1.0 docs */}

{/* Railroad diagram omitted - see 3.1.0 docs */}

Keywords and parameters:

* `column_name` - a column name.
* `DATA TYPE` - the [data type](data-types.md) allowed in the column.
* `identifier` - the random identifier for the row. Can be generated by using the `RAND_UUID` function.
* `literal_value` - a value to be assigned as default.
* `CURRENT_TIMESTAMP` - the function that returns current time. Can only be used for `TIMESTAMP WITH LOCAL TIME ZONE` columns.
* `interval` - the time interval by which the timestamp will be offset. Required if `CURRENT_TIMESTAMP` is used. The interval can be specified in:

  - `SECONDS`
  - `MINUTES`
  - `HOURS`
  - `DAYS`
  - `MONTHS`

  If the interval is `0`, current time is used.

Referenced by:

* [CREATE TABLE](ddl.md#create-table)
* [ALTER TABLE](ddl.md#alter-table)
* [project_item](#project_item)
* [join_condition](#join_condition)

## column_definition_or_list

{/* Railroad diagram omitted - see 3.1.0 docs */}

Keywords and parameters:

* `column_name` - a column name.
* `data_type` - a valid [data type](data-types.md).

Referenced by:

* [ALTER TABLE](ddl.md#alter-table)
* [with_item](#with_item)

## column_list

{/* Railroad diagram omitted - see 3.1.0 docs */}

Keywords and parameters:

* `column_name` - a column name.

Referenced by:

* [INSERT](dml.md#insert)
* [join_condition ](#join_condition)

## column_name_or_list

{/* Railroad diagram omitted - see 3.1.0 docs */}

Keywords and parameters:

* `column_name` - a column name.

Referenced by:

* [ALTER TABLE](ddl.md#alter-table)

## constraint

{/* Railroad diagram omitted - see 3.1.0 docs */}

Keywords and parameters:

* `constraint_name` - a name of the constraint.

Referenced by:

* [CREATE TABLE](ddl.md#create-table)

## group_item

{/* Railroad diagram omitted - see 3.1.0 docs */}

### Parameters

- `expression` - a valid SQL expression that returns the values that must be assigned to the `identifier`.

Referenced by:

* [SELECT](operational-commands.md#select)

## join_condition

{/* Railroad diagram omitted - see 3.1.0 docs */}

### Parameters

- `boolean_expression` - an SQL expression that returns a boolean value. Only the records for which `TRUE` was returned will be returned. If not specified, all matching records are returned.

Referenced by:

* [table_expression](#table_expression)

## order_item

{/* Railroad diagram omitted - see 3.1.0 docs */}

### Parameters

- `expression` - a valid SQL expression that denotes the specific item in the SELECT clause.

Referenced by:

* [query](#query)

## parameter

{/* Railroad diagram omitted - see 3.1.0 docs */}

Parameters:

* `parameter_name` - the name of the parameter.
* `parameter_value` - the value of the parameter.

When a parameter is specified, you can provide it as a literal value or as an identifier. For example:

```
CREATE ZONE test_zone;
CREATE TABLE test_table (id INT PRIMARY KEY, val INT) WITH PRIMARY_ZONE=test_zone;
```

In this case, `test_zone` is the identifier, and is used as an identifier. When used like this, the parameters are not case-sensitive.

```
CREATE ZONE "test_zone";
CREATE TABLE test_table (id INT PRIMARY KEY, val INT) WITH PRIMARY_ZONE='test_zone';
```

In this case, `test_zone` is created as a literal value, and is used as a literal. When used like this, the parameter is case-sensitive.

```
CREATE ZONE test_zone;
CREATE TABLE test_table (id INT PRIMARY KEY, val INT) WITH PRIMARY_ZONE=`TEST_ZONE`;
```

In this case, `test_zone` is created as an identifier, and is case-insensitive. As such, when `TEST_ZONE` is used as a literal, it still matches the identifier.

Referenced by:

* [CREATE ZONE](distribution-zones.md#create-zone)
* [ALTER ZONE](distribution-zones.md#alter-zone)

## project_item

{/* Railroad diagram omitted - see 3.1.0 docs */}

### Parameters

- `expression` - a valid SQL expression that denotes the specific item in the SELECT clause.
- `table_alias` - a qualified table alias to use.

Referenced by:

* [SELECT](operational-commands.md#select)
* [select_without_from](#select_without_from)

## qualified_table_name

{/* Railroad diagram omitted - see 3.1.0 docs */}

Keywords and parameters:

* `schema` - a name of the table schema.
* `table_name` - a name of the table.

Referenced by:

* [CREATE TABLE](ddl.md#create-table)
* [ALTER TABLE](ddl.md#alter-table)
* [DROP TABLE](ddl.md#drop-table)
* [CREATE INDEX](ddl.md#create-index)
* [DELETE](dml.md#delete)
* [INSERT](dml.md#insert)
* [MERGE](dml.md#merge)
* [UPDATE](dml.md#update)
* [table_primary](#table_primary)

## query

{/* Railroad diagram omitted - see 3.1.0 docs */}

### Parameters

- `expression` - a valid SQL expression.
- `start` - the number of result to start the query from.
- `count` - the number of values to fetch.

Referenced by:

* [INSERT](dml.md#insert)
* [with_item](#with_item)
* [table_primary](#table_primary)

## select_without_from

{/* Railroad diagram omitted - see 3.1.0 docs */}

Referenced by:

* [query](#query)

## sorted_column_list

{/* Railroad diagram omitted - see 3.1.0 docs */}

Keywords and parameters:

* `column_name` - a column name.
* `NULLS FIRST` - if specified, places any NULL values before all non-NULL in that column's ordering.
* `NULLS LAST` - if specified, places NULLs after all non-NULLs in that column's ordering.

Referenced by:

* [CREATE INDEX](ddl.md#create-index)
* [constraint](#constraint)

## table_expression

{/* Railroad diagram omitted - see 3.1.0 docs */}

### Parameters

Referenced by:

* [SELECT](operational-commands.md#select)

## table_primary

{/* Railroad diagram omitted - see 3.1.0 docs */}

{/* Railroad diagram omitted - see 3.1.0 docs */}

### Parameters

- `hint_comment` - an sql [optimizer hint](../sql-tuning/sql-tuning.md#optimizer-hints).
- `expression` - a valid SQL expression.
- `function_name` - the name of the [SQL function](operators-and-functions.md) to use.

Referenced by:

* [table_reference](#table_reference)

## table_reference

{/* Railroad diagram omitted - see 3.1.0 docs */}

### Parameters

- `alias` - the alias that will be used for the table.
- `column_alias` - the alias used for column.

Referenced by:

* [table_expression](#table_expression)

## with_item

{/* Railroad diagram omitted - see 3.1.0 docs */}

Referenced by:

* [query](#query)