f543d6a1ee
### What changes were proposed in this pull request? Need to address a few more comments ### Why are the changes needed? Fix a few problems ### Does this PR introduce any user-facing change? Yes ### How was this patch tested? Manually build and check Closes #28306 from huaxingao/literal-folllowup. Authored-by: Huaxin Gao <huaxing@us.ibm.com> Signed-off-by: Takeshi Yamamuro <yamamuro@apache.org>
540 lines
10 KiB
Markdown
540 lines
10 KiB
Markdown
---
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layout: global
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title: Literals
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displayTitle: Literals
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license: |
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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---
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A literal (also known as a constant) represents a fixed data value. Spark SQL supports the following literals:
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* [String Literal](#string-literal)
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* [Binary Literal](#binary-literal)
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* [Null Literal](#null-literal)
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* [Boolean Literal](#boolean-literal)
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* [Numeric Literal](#numeric-literal)
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* [Datetime Literal](#datetime-literal)
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* [Interval Literal](#interval-literal)
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### String Literal
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A string literal is used to specify a character string value.
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#### Syntax
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{% highlight sql %}
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'c [ ... ]' | "c [ ... ]"
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{% endhighlight %}
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#### <em>Parameters</em>
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<dl>
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<dt><code><em>c</em></code></dt>
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<dd>
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One character from the character set. Use <code>\</code> to escape special characters (e.g., <code>'</code> or <code>\</code>).
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</dd>
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</dl>
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#### <em>Examples</em>
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{% highlight sql %}
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SELECT 'Hello, World!' AS col;
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+-------------+
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| col|
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+-------------+
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|Hello, World!|
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+-------------+
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SELECT "SPARK SQL" AS col;
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+---------+
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| col|
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+---------+
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|Spark SQL|
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+---------+
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SELECT 'it\'s $10.' AS col;
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+---------+
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| col|
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+---------+
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|It's $10.|
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+---------+
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{% endhighlight %}
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### Binary Literal
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A binary literal is used to specify a byte sequence value.
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#### Syntax
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{% highlight sql %}
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X { 'c [ ... ]' | "c [ ... ]" }
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{% endhighlight %}
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#### <em>Parameters</em>
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<dl>
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<dt><code><em>c</em></code></dt>
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<dd>
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One character from the character set.
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</dd>
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</dl>
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#### <em>Examples</em>
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{% highlight sql %}
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SELECT X'123456' AS col;
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+----------+
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| col|
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+----------+
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|[12 34 56]|
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+----------+
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{% endhighlight %}
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### Null Literal
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A null literal is used to specify a null value.
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#### Syntax
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{% highlight sql %}
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NULL
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{% endhighlight %}
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#### Examples
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{% highlight sql %}
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SELECT NULL AS col;
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+----+
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| col|
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+----+
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|NULL|
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+----+
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{% endhighlight %}
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### Boolean Literal
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A boolean literal is used to specify a boolean value.
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#### Syntax
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{% highlight sql %}
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TRUE | FALSE
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{% endhighlight %}
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#### Examples
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{% highlight sql %}
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SELECT TRUE AS col;
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+----+
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| col|
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+----+
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|true|
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+----+
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{% endhighlight %}
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### Numeric Literal
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A numeric literal is used to specify a fixed or floating-point number.
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#### Integral Literal
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#### Syntax
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{% highlight sql %}
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[ + | - ] digit [ ... ] [ L | S | Y ]
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{% endhighlight %}
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#### Parameters
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<dl>
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<dt><code><em>digit</em></code></dt>
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<dd>
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Any numeral from 0 to 9.
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</dd>
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</dl>
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<dl>
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<dt><code><em>L</em></code></dt>
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<dd>
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Case insensitive, indicates <code>BIGINT</code>, which is a 8-byte signed integer number.
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</dd>
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</dl>
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<dl>
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<dt><code><em>S</em></code></dt>
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<dd>
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Case insensitive, indicates <code>SMALLINT</code>, which is a 2-byte signed integer number.
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</dd>
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</dl>
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<dl>
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<dt><code><em>Y</em></code></dt>
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<dd>
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Case insensitive, indicates <code>TINYINT</code>, which is a 1-byte signed integer number.
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</dd>
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</dl>
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<dl>
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<dt><code><em>default (no postfix)</em></code></dt>
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<dd>
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Indicates a 4-byte signed integer number.
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</dd>
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</dl>
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#### Examples
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{% highlight sql %}
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SELECT -2147483648 AS col;
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+-----------+
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| col|
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+-----------+
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|-2147483648|
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+-----------+
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SELECT 9223372036854775807l AS col;
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+-------------------+
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| col|
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+-------------------+
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|9223372036854775807|
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+-------------------+
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SELECT -32Y AS col;
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+---+
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|col|
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+---+
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|-32|
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+---+
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SELECT 482S AS col;
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+---+
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|col|
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+---+
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|482|
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+---+
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{% endhighlight %}
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#### Fractional Literals
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#### Syntax
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decimal literals:
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{% highlight sql %}
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decimal_digits { [ BD ] | [ exponent BD ] } | digit [ ... ] [ exponent ] BD
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{% endhighlight %}
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double literals:
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{% highlight sql %}
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decimal_digits { D | exponent [ D ] } | digit [ ... ] { exponent [ D ] | [ exponent ] D }
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{% endhighlight %}
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While decimal_digits is defined as
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{% highlight sql %}
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[ + | - ] { digit [ ... ] . [ digit [ ... ] ] | . digit [ ... ] }
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{% endhighlight %}
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and exponent is defined as
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{% highlight sql %}
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E [ + | - ] digit [ ... ]
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{% endhighlight %}
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#### Parameters
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<dl>
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<dt><code><em>digit</em></code></dt>
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<dd>
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Any numeral from 0 to 9.
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</dd>
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</dl>
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<dl>
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<dt><code><em>D</em></code></dt>
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<dd>
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Case insensitive, indicates <code>DOUBLE</code>, which is a 8-byte double-precision floating point number.
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</dd>
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</dl>
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<dl>
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<dt><code><em>BD</em></code></dt>
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<dd>
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Case insensitive, indicates <code>DECIMAL</code>, with the total number of digits as precision and the number of digits to right of decimal point as scale.
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</dd>
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</dl>
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#### Examples
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{% highlight sql %}
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SELECT 12.578 AS col;
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+------+
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| col|
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+------+
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|12.578|
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+------+
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SELECT -0.1234567 AS col;
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+----------+
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| col|
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+----------+
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|-0.1234567|
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+----------+
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SELECT -.1234567 AS col;
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+----------+
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| col|
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+----------+
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|-0.1234567|
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+----------+
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SELECT 123. AS col;
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+---+
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|col|
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+---+
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|123|
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+---+
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SELECT 123.BD AS col;
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+---+
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|col|
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+---+
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|123|
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+---+
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SELECT 5E2 AS col;
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+-----+
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| col|
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+-----+
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|500.0|
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+-----+
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SELECT 5D AS col;
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+---+
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|col|
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+---+
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|5.0|
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+---+
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SELECT -5BD AS col;
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+---+
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|col|
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+---+
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| -5|
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+---+
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SELECT 12.578e-2d AS col;
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+-------+
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| col|
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+-------+
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|0.12578|
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+-------+
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SELECT -.1234567E+2BD AS col;
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+---------+
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| col|
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+---------+
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|-12.34567|
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+---------+
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SELECT +3.e+3 AS col;
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+------+
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| col|
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+------+
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|3000.0|
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+------+
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SELECT -3.E-3D AS col;
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+------+
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| col|
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+------+
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|-0.003|
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+------+
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{% endhighlight %}
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### Datetime Literal
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A Datetime literal is used to specify a datetime value.
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#### Date Literal
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#### Syntax
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{% highlight sql %}
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DATE { 'yyyy' |
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'yyyy-[m]m' |
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'yyyy-[m]m-[d]d' |
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'yyyy-[m]m-[d]d[T]' }
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{% endhighlight %}
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Note: defaults to <code>01</code> if month or day is not specified.
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#### Examples
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{% highlight sql %}
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SELECT DATE '1997' AS col;
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+----------+
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| col|
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+----------+
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|1997-01-01|
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+----------+
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SELECT DATE '1997-01' AS col;
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+----------+
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| col|
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+----------+
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|1997-01-01|
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+----------+
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SELECT DATE '2011-11-11' AS col;
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+----------+
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| col|
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+----------+
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|2011-11-11|
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+----------+
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{% endhighlight %}
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#### Timestamp Literal
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#### Syntax
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{% highlight sql %}
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TIMESTAMP { 'yyyy' |
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'yyyy-[m]m' |
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'yyyy-[m]m-[d]d' |
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'yyyy-[m]m-[d]d ' |
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'yyyy-[m]m-[d]d[T][h]h[:]' |
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'yyyy-[m]m-[d]d[T][h]h:[m]m[:]' |
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'yyyy-[m]m-[d]d[T][h]h:[m]m:[s]s[.]' |
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'yyyy-[m]m-[d]d[T][h]h:[m]m:[s]s.[ms][ms][ms][us][us][us][zone_id]'}
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{% endhighlight %}
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Note: defaults to <code>00</code> if hour, minute or second is not specified. <br><br>
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`zone_id` should have one of the forms:
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<ul>
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<li>Z - Zulu time zone UTC+0</li>
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<li>+|-[h]h:[m]m</li>
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<li>An id with one of the prefixes UTC+, UTC-, GMT+, GMT-, UT+ or UT-, and a suffix in the formats:
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<ul>
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<li>+|-h[h]</li>
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<li>+|-hh[:]mm</li>
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<li>+|-hh:mm:ss</li>
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<li>+|-hhmmss</li>
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</ul>
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</li>
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<li>Region-based zone IDs in the form <code>area/city</code>, such as <code>Europe/Paris</code></li>
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</ul>
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Note: defaults to the session local timezone (set via <code>spark.sql.session.timeZone</code>) if <code>zone_id</code> is not specified.
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#### Examples
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{% highlight sql %}
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SELECT TIMESTAMP '1997-01-31 09:26:56.123' AS col;
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+-----------------------+
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| col|
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+-----------------------+
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|1997-01-31 09:26:56.123|
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+-----------------------+
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SELECT TIMESTAMP '1997-01-31 09:26:56.66666666UTC+08:00' AS col;
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+--------------------------+
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| col |
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+--------------------------+
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|1997-01-30 17:26:56.666666|
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+--------------------------+
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SELECT TIMESTAMP '1997-01' AS col;
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+-------------------+
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| col|
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+-------------------+
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|1997-01-01 00:00:00|
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+-------------------+
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{% endhighlight %}
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### Interval Literal
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An interval literal is used to specify a fixed period of time.
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#### Syntax
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{% highlight sql %}
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{ INTERVAL interval_value interval_unit [ interval_value interval_unit ... ] |
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INTERVAL 'interval_value interval_unit [ interval_value interval_unit ... ]' |
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INTERVAL interval_string_value interval_unit TO interval_unit }
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{% endhighlight %}
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#### Parameters
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<dl>
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<dt><code><em>interval_value</em></code></dt>
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<dd>
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<b>Syntax:</b>
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<code>
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[ + | - ] number_value | '[ + | - ] number_value'
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</code><br>
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</dd>
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</dl>
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<dl>
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<dt><code><em>interval_string_value</em></code></dt>
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<dd>
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year-month/day-time interval string.
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</dd>
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</dl>
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<dl>
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<dt><code><em>interval_unit</em></code></dt>
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<dd>
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<b>Syntax:</b><br>
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<code>
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YEAR[S] | MONTH[S] | WEEK[S] | DAY[S] | HOUR[S] | MINUTE[S] | SECOND[S] | <br>
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MILLISECOND[S] | MICROSECOND[S]
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</code>
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</dd>
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</dl>
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#### Examples
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{% highlight sql %}
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SELECT INTERVAL 3 YEAR AS col;
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+-------+
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| col|
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+-------+
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|3 years|
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+-------+
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SELECT INTERVAL -2 HOUR '3' MINUTE AS col;
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+--------------------+
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| col|
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+--------------------+
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|-1 hours -57 minutes|
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+--------------------+
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SELECT INTERVAL '1 YEAR 2 DAYS 3 HOURS';
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+----------------------+
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| col|
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+----------------------+
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|1 years 2 days 3 hours|
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+----------------------+
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SELECT INTERVAL 1 YEARS 2 MONTH 3 WEEK 4 DAYS 5 HOUR 6 MINUTES 7 SECOND 8
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MILLISECOND 9 MICROSECONDS AS col;
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+-----------------------------------------------------------+
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| col|
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+-----------------------------------------------------------+
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|1 years 2 months 25 days 5 hours 6 minutes 7.008009 seconds|
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+-----------------------------------------------------------+
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SELECT INTERVAL '2-3' YEAR TO MONTH AS col;
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+----------------+
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| col|
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+----------------+
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|2 years 3 months|
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+----------------+
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SELECT INTERVAL '20 15:40:32.99899999' DAY TO SECOND AS col;
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+---------------------------------------------+
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| col|
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+---------------------------------------------+
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|20 days 15 hours 40 minutes 32.998999 seconds|
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+---------------------------------------------+
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{% endhighlight %}
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