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<body id="conditional_functions">
<h1 class="title topictitle1" id="ariaid-title1">Impala Conditional Functions</h1>
<div class="body conbody">
<p class="p">
Impala supports the following conditional functions for testing equality, comparison
operators, and nullity:
</p>
<ul class="ul">
<li class="li">
<a class="xref" href="#conditional_functions__case">CASE</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__case2">CASE2</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__coalesce">COALESCE</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__decode">DECODE</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__if">IF</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__ifnull">IFNULL</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__isfalse">ISFALSE</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__isnotfalse">ISNOTFALSE</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__isnottrue">ISNOTTRUE</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__isnull">ISNULL</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__istrue">ISTRUE</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__nonnullvalue">NONNULLVALUE</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__nullif">NULLIF</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__nullifzero">NULLIFZERO</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__nullvalue">NULLVALUE</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__nvl">NVL</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__nvl2">NVL2</a>
</li>
<li class="li">
<a class="xref" href="#conditional_functions__zeroifnull">ZEROIFNULL</a>
</li>
</ul>
<dl class="dl">
<dt class="dt dlterm" id="conditional_functions__case">
CASE a WHEN b THEN c [WHEN d THEN e]... [ELSE f] END
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Compares an expression to one or more possible values, and returns a
corresponding result when a match is found.
<p class="p">
<strong class="ph b">Return type:</strong> same as the initial argument value, except that integer values are
promoted to <code class="ph codeph">BIGINT</code> and floating-point values are promoted to
<code class="ph codeph">DOUBLE</code>; use <code class="ph codeph">CAST()</code> when inserting into a smaller
numeric column
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong>
</p>
<p class="p">
In this form of the <code class="ph codeph">CASE</code> expression, the initial value
<code class="ph codeph">A</code> being evaluated for each row it typically a column reference, or
an expression involving a column. This form can only compare against a set of
specified values, not ranges, multi-value comparisons such as
<code class="ph codeph">BETWEEN</code> or <code class="ph codeph">IN</code>, regular expressions, or
<code class="ph codeph">NULL</code>.
</p>
<p class="p">
<strong class="ph b">Examples:</strong>
</p>
<p class="p">
Although this example is split across multiple lines, you can put any or all parts
of a <code class="ph codeph">CASE</code> expression on a single line, with no punctuation or other
separators between the <code class="ph codeph">WHEN</code>, <code class="ph codeph">ELSE</code>, and
<code class="ph codeph">END</code> clauses.
</p>
<pre class="pre codeblock"><code>select case x
when 1 then 'one'
when 2 then 'two'
when 0 then 'zero'
else 'out of range'
end
from t1;
</code></pre>
</dd>
<dt class="dt dlterm" id="conditional_functions__case2">
CASE WHEN a THEN b [WHEN c THEN d]... [ELSE e] END
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Tests whether any of a sequence of expressions is
<code class="ph codeph">TRUE</code>, and returns a corresponding result for the first true
expression.
<p class="p">
<strong class="ph b">Return type:</strong> same as the initial argument value, except that integer values are
promoted to <code class="ph codeph">BIGINT</code> and floating-point values are promoted to
<code class="ph codeph">DOUBLE</code>; use <code class="ph codeph">CAST()</code> when inserting into a smaller
numeric column
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong>
</p>
<p class="p">
<code class="ph codeph">CASE</code> expressions without an initial test value have more
flexibility. For example, they can test different columns in different
<code class="ph codeph">WHEN</code> clauses, or use comparison operators such as
<code class="ph codeph">BETWEEN</code>, <code class="ph codeph">IN</code> and <code class="ph codeph">IS NULL</code> rather
than comparing against discrete values.
</p>
<p class="p">
<code class="ph codeph">CASE</code> expressions are often the foundation of long queries that
summarize and format results for easy-to-read reports. For example, you might use a
<code class="ph codeph">CASE</code> function call to turn values from a numeric column into
category strings corresponding to integer values, or labels such as <span class="q">"Small"</span>,
<span class="q">"Medium"</span> and <span class="q">"Large"</span> based on ranges. Then subsequent parts of the query
might aggregate based on the transformed values, such as how many values are
classified as small, medium, or large. You can also use <code class="ph codeph">CASE</code> to
signal problems with out-of-bounds values, <code class="ph codeph">NULL</code> values, and so on.
</p>
<p class="p">
By using operators such as <code class="ph codeph">OR</code>, <code class="ph codeph">IN</code>,
<code class="ph codeph">REGEXP</code>, and so on in <code class="ph codeph">CASE</code> expressions, you can
build extensive tests and transformations into a single query. Therefore,
applications that construct SQL statements often rely heavily on
<code class="ph codeph">CASE</code> calls in the generated SQL code.
</p>
<p class="p">
Because this flexible form of the <code class="ph codeph">CASE</code> expressions allows you to
perform many comparisons and call multiple functions when evaluating each row, be
careful applying elaborate <code class="ph codeph">CASE</code> expressions to queries that process
large amounts of data. For example, when practical, evaluate and transform values
through <code class="ph codeph">CASE</code> after applying operations such as aggregations that
reduce the size of the result set; transform numbers to strings after performing
joins with the original numeric values.
</p>
<p class="p">
<strong class="ph b">Examples:</strong>
</p>
<p class="p">
Although this example is split across multiple lines, you can put any or all parts
of a <code class="ph codeph">CASE</code> expression on a single line, with no punctuation or other
separators between the <code class="ph codeph">WHEN</code>, <code class="ph codeph">ELSE</code>, and
<code class="ph codeph">END</code> clauses.
</p>
<pre class="pre codeblock"><code>select case
when dayname(now()) in ('Saturday','Sunday') then 'result undefined on weekends'
when x &gt; y then 'x greater than y'
when x = y then 'x and y are equal'
when x is null or y is null then 'one of the columns is null'
else null
end
from t1;
</code></pre>
</dd>
<dt class="dt dlterm" id="conditional_functions__coalesce">
COALESCE(type v1, type v2, ...)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Returns the first specified argument that is not
<code class="ph codeph">NULL</code>, or <code class="ph codeph">NULL</code> if all arguments are
<code class="ph codeph">NULL</code>.
<p class="p">
<strong class="ph b">Return type:</strong> same as the initial argument value, except that integer values are
promoted to <code class="ph codeph">BIGINT</code> and floating-point values are promoted to
<code class="ph codeph">DOUBLE</code>; use <code class="ph codeph">CAST()</code> when inserting into a smaller
numeric column
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__decode">
DECODE(type expression, type search1, type result1 [, type search2, type result2 ...]
[, type default] )
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Compares the first argument, <code class="ph codeph">expression</code>, to the
<code class="ph codeph">search</code> expressions using the <code class="ph codeph">IS NOT DISTINCT</code>
operator, and returns:
<ul class="ul">
<li class="li">
The corresponding <code class="ph codeph">result</code> when a match is found.
</li>
<li class="li">
The first corresponding <code class="ph codeph">result</code> if there are more than one
matching <code class="ph codeph">search</code> expressions.
</li>
<li class="li">
The <code class="ph codeph">default</code> expression if none of the search expressions matches
the first argument <code class="ph codeph">expression</code>.
</li>
<li class="li">
<code class="ph codeph">NULL</code> if the final <code class="ph codeph">default</code> expression is omitted
and none of the <code class="ph codeph">search</code> expressions matches the first argument.
</li>
</ul>
<div class="p">
<strong class="ph b">Return type:</strong> Same as the first argument with the following exceptions:
<ul class="ul">
<li class="li">
Integer values are promoted to <code class="ph codeph">BIGINT</code>.
</li>
<li class="li">
Floating-point values are promoted to <code class="ph codeph">DOUBLE</code>.
</li>
<li class="li">
Use <code class="ph codeph">CAST()</code> when inserting into a smaller numeric column.
</li>
</ul>
</div>
<p class="p">
<strong class="ph b">Usage notes:</strong>
</p>
<ul class="ul">
<li class="li">
Can be used as shorthand for a <code class="ph codeph">CASE</code> expression.
</li>
<li class="li">
The first argument, <code class="ph codeph">expression</code>, and the search expressions must
be of the same type or convertible types.
</li>
<li class="li">
The result expression can be a different type, but all result expressions must be
of the same type.
</li>
<li class="li">
Returns a successful match if the first argument is <code class="ph codeph">NULL</code> and a
search expression is also <code class="ph codeph">NULL</code>.
</li>
<li class="li">
<code class="ph codeph">NULL</code> can be used as a search expression.
</li>
</ul>
<p class="p">
<strong class="ph b">Examples:</strong>
</p>
<p class="p">
The following example translates numeric day values into weekday names, such as 1 to
Monday, 2 to Tuesday, etc.
</p>
<pre class="pre codeblock"><code>SELECT event, DECODE(day_of_week, 1, "Monday", 2, "Tuesday", 3, "Wednesday",
4, "Thursday", 5, "Friday", 6, "Saturday", 7, "Sunday", "Unknown day")
FROM calendar;
</code></pre>
</dd>
<dt class="dt dlterm" id="conditional_functions__if">
IF(BOOLEAN condition, type ifTrue, type ifFalseOrNull)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Tests an expression and returns a corresponding result depending on
whether the result is <code class="ph codeph">TRUE</code>, <code class="ph codeph">FALSE</code>, or
<code class="ph codeph">NULL</code>.
<p class="p">
<strong class="ph b">Return type:</strong> Same as the <code class="ph codeph">ifTrue</code> argument value
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__ifnull">
IFNULL(type a, type ifNull)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Alias for the <code class="ph codeph">ISNULL()</code> function, with the same
behavior. To simplify porting SQL with vendor extensions to Impala.
<p class="p">
<strong class="ph b">Added in:</strong> Impala 1.3.0
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__isfalse">
ISFALSE(BOOLEAN expression)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Returns <code class="ph codeph">TRUE</code> if the expression is
<code class="ph codeph">FALSE</code>. Returns <code class="ph codeph">FALSE</code> if the expression is
<code class="ph codeph">TRUE</code> or <code class="ph codeph">NULL</code>.
<p class="p">
Same as the <code class="ph codeph">IS FALSE</code> operator.
</p>
<p class="p">
Similar to <code class="ph codeph">ISNOTTRUE()</code>, except it returns the opposite value for a
<code class="ph codeph">NULL</code> argument.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> <code class="ph codeph">BOOLEAN</code>
</p>
<p class="p">
<strong class="ph b">Added in:</strong> <span class="keyword">Impala 2.2.0</span>
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong>
</p>
<p class="p">
In <span class="keyword">Impala 2.11</span> and higher, you can use the operators <code class="ph codeph">IS
[NOT] TRUE</code> and <code class="ph codeph">IS [NOT] FALSE</code> as equivalents for the built-in
functions <code class="ph codeph">ISTRUE()</code>, <code class="ph codeph">ISNOTTRUE()</code>,
<code class="ph codeph">ISFALSE()</code>, and <code class="ph codeph">ISNOTFALSE()</code>.
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__isnotfalse">
ISNOTFALSE(BOOLEAN expression)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Tests if a Boolean expression is not <code class="ph codeph">FALSE</code> (that is,
either <code class="ph codeph">TRUE</code> or <code class="ph codeph">NULL</code>). Returns <code class="ph codeph">TRUE</code>
if so. If the argument is <code class="ph codeph">NULL</code>, returns <code class="ph codeph">TRUE</code>.
<p class="p">
Same as the <code class="ph codeph">IS NOT FALSE</code> operator.
</p>
<p class="p">
Similar to <code class="ph codeph">ISTRUE()</code>, except it returns the opposite value for a
<code class="ph codeph">NULL</code> argument.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> <code class="ph codeph">BOOLEAN</code>
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong> Primarily for compatibility with code containing industry extensions
to SQL.
</p>
<p class="p">
<strong class="ph b">Added in:</strong> <span class="keyword">Impala 2.2.0</span>
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong>
</p>
<p class="p">
In <span class="keyword">Impala 2.11</span> and higher, you can use the operators <code class="ph codeph">IS
[NOT] TRUE</code> and <code class="ph codeph">IS [NOT] FALSE</code> as equivalents for the built-in
functions <code class="ph codeph">ISTRUE()</code>, <code class="ph codeph">ISNOTTRUE()</code>,
<code class="ph codeph">ISFALSE()</code>, and <code class="ph codeph">ISNOTFALSE()</code>.
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__isnottrue">
ISNOTTRUE(BOOLEAN expression)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Tests if a Boolean expression is not <code class="ph codeph">TRUE</code> (that is,
either <code class="ph codeph">FALSE</code> or <code class="ph codeph">NULL</code>). Returns <code class="ph codeph">TRUE</code>
if so. If the argument is <code class="ph codeph">NULL</code>, returns <code class="ph codeph">TRUE</code>.
<p class="p">
Same as the <code class="ph codeph">IS NOT TRUE</code> operator.
</p>
<p class="p">
Similar to <code class="ph codeph">ISFALSE()</code>, except it returns the opposite value for a
<code class="ph codeph">NULL</code> argument.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> <code class="ph codeph">BOOLEAN</code>
</p>
<p class="p">
<strong class="ph b">Added in:</strong> <span class="keyword">Impala 2.2.0</span>
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong>
</p>
<p class="p">
In <span class="keyword">Impala 2.11</span> and higher, you can use the operators <code class="ph codeph">IS
[NOT] TRUE</code> and <code class="ph codeph">IS [NOT] FALSE</code> as equivalents for the built-in
functions <code class="ph codeph">ISTRUE()</code>, <code class="ph codeph">ISNOTTRUE()</code>,
<code class="ph codeph">ISFALSE()</code>, and <code class="ph codeph">ISNOTFALSE()</code>.
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__isnull">
ISNULL(type a, type ifNull)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Tests if an expression is <code class="ph codeph">NULL</code>, and returns the
expression result value if not. If the first argument is <code class="ph codeph">NULL</code>,
returns the second argument.
<p class="p">
<strong class="ph b">Compatibility notes:</strong> Equivalent to the <code class="ph codeph">NVL()</code> function from
Oracle Database or <code class="ph codeph">IFNULL()</code> from MySQL. The <code class="ph codeph">NVL()</code>
and <code class="ph codeph">IFNULL()</code> functions are also available in Impala.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> Same as the first argument value
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__istrue">
ISTRUE(BOOLEAN expression)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Returns <code class="ph codeph">TRUE</code> if the expression is
<code class="ph codeph">TRUE</code>. Returns <code class="ph codeph">FALSE</code> if the expression is
<code class="ph codeph">FALSE</code> or <code class="ph codeph">NULL</code>.
<p class="p">
Same as the <code class="ph codeph">IS TRUE</code> operator.
</p>
<p class="p">
Similar to <code class="ph codeph">ISNOTFALSE()</code>, except it returns the opposite value for a
<code class="ph codeph">NULL</code> argument.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> <code class="ph codeph">BOOLEAN</code>
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong> Primarily for compatibility with code containing industry extensions
to SQL.
</p>
<p class="p">
<strong class="ph b">Added in:</strong> <span class="keyword">Impala 2.2.0</span>
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong>
</p>
<p class="p">
In <span class="keyword">Impala 2.11</span> and higher, you can use the operators <code class="ph codeph">IS
[NOT] TRUE</code> and <code class="ph codeph">IS [NOT] FALSE</code> as equivalents for the built-in
functions <code class="ph codeph">ISTRUE()</code>, <code class="ph codeph">ISNOTTRUE()</code>,
<code class="ph codeph">ISFALSE()</code>, and <code class="ph codeph">ISNOTFALSE()</code>.
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__nonnullvalue">
NONNULLVALUE(type expression)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Returns <code class="ph codeph">TRUE</code> if the expression is non-null and
returns <code class="ph codeph">FALSE</code> if the expression is <code class="ph codeph">NULL</code>.
<p class="p">
Same as the <code class="ph codeph">IS NOT NULL</code> operator.
</p>
<p class="p">
The converse of <code class="ph codeph">NULLVALUE()</code>.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> <code class="ph codeph">BOOLEAN</code>
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong> Primarily for compatibility with code containing industry extensions
to SQL.
</p>
<p class="p">
<strong class="ph b">Added in:</strong> <span class="keyword">Impala 2.2.0</span>
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__nullif">
NULLIF(type expr1, type expr2)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Returns <code class="ph codeph">NULL</code> if the two specified arguments are
equal. If the specified arguments are not equal, returns the value of
<var class="keyword varname">expr1</var>. The data types of the expressions must be compatible,
according to the conversion rules from <a class="xref" href="impala_datatypes.html#datatypes">Data Types</a>.
You cannot use an expression that evaluates to <code class="ph codeph">NULL</code> for
<var class="keyword varname">expr1</var>; that way, you can distinguish a return value of
<code class="ph codeph">NULL</code> from an argument value of <code class="ph codeph">NULL</code>, which would
never match <var class="keyword varname">expr2</var>.
<p class="p">
<strong class="ph b">Usage notes:</strong> This function is effectively shorthand for a
<code class="ph codeph">CASE</code> expression of the form:
</p>
<pre class="pre codeblock"><code>CASE
WHEN <var class="keyword varname">expr1</var> = <var class="keyword varname">expr2</var> THEN NULL
ELSE <var class="keyword varname">expr1</var>
END</code></pre>
<p class="p">
It is commonly used in division expressions, to produce a <code class="ph codeph">NULL</code>
result instead of a divide-by-zero error when the divisor is equal to zero:
</p>
<pre class="pre codeblock"><code>select 1.0 / nullif(c1,0) as reciprocal from t1;</code></pre>
<p class="p">
You might also use it for compatibility with other database systems that support the
same <code class="ph codeph">NULLIF()</code> function.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> same as the initial argument value, except that integer values are
promoted to <code class="ph codeph">BIGINT</code> and floating-point values are promoted to
<code class="ph codeph">DOUBLE</code>; use <code class="ph codeph">CAST()</code> when inserting into a smaller
numeric column
</p>
<p class="p">
<strong class="ph b">Added in:</strong> Impala 1.3.0
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__nullifzero">
NULLIFZERO(type numeric_expr)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Returns <code class="ph codeph">NULL</code> if the numeric expression evaluates to
0, otherwise returns the result of the expression.
<p class="p">
<strong class="ph b">Usage notes:</strong> Used to avoid error conditions such as divide-by-zero in numeric
calculations. Serves as shorthand for a more elaborate <code class="ph codeph">CASE</code>
expression, to simplify porting SQL with vendor extensions to Impala.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> Same type as the input argument
</p>
<p class="p">
<strong class="ph b">Added in:</strong> Impala 1.3.0
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__nullvalue">
NULLVALUE(type expression)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Returns <code class="ph codeph">TRUE</code> if the expression is
<code class="ph codeph">NULL</code>, and returns <code class="ph codeph">FALSE</code> otherwise.
<p class="p">
Same as the <code class="ph codeph">IS NULL</code> operator.
</p>
<p class="p">
The converse of <code class="ph codeph">NONNULLVALUE()</code>.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> <code class="ph codeph">BOOLEAN</code>
</p>
<p class="p">
<strong class="ph b">Usage notes:</strong> Primarily for compatibility with code containing industry extensions
to SQL.
</p>
<p class="p">
<strong class="ph b">Added in:</strong> <span class="keyword">Impala 2.2.0</span>
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__nvl">
NVL(type a, type ifNull)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Alias for the <code class="ph codeph">ISNULL()</code> function. Returns the first
argument if the first argument is not <code class="ph codeph">NULL</code>. Returns the second
argument if the first argument is <code class="ph codeph">NULL</code>.
<p class="p">
Equivalent to the <code class="ph codeph">NVL()</code> function in Oracle Database or
<code class="ph codeph">IFNULL()</code> in MySQL.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> Same as the first argument value
</p>
<p class="p">
<strong class="ph b">Added in:</strong> Impala 1.1
</p>
</dd>
<dt class="dt dlterm" id="conditional_functions__nvl2">
NVL2(type a, type ifNotNull, type ifNull)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Returns the second argument,
<code class="ph codeph">ifNotNull</code>, if the first argument is not
<code class="ph codeph">NULL</code>. Returns the third argument,
<code class="ph codeph">ifNull</code>, if the first argument is
<code class="ph codeph">NULL</code>. <p class="p"> Equivalent to the <code class="ph codeph">NVL2()</code>
function in Oracle Database. </p>
<p class="p">
<strong class="ph b">Return type:</strong> Same as the first argument value </p>
<p class="p">
<strong class="ph b">Added in:</strong> <span class="keyword">Impala 2.9.0</span>
</p>
<p class="p">
<strong class="ph b">Examples:</strong>
</p>
<pre class="pre codeblock"><code>
SELECT NVL2(NULL, 999, 0); -- Returns 0
SELECT NVL2('ABC', 'Is Not Null', 'Is Null'); -- Returns 'Is Not Null'</code></pre>
</dd>
<dt class="dt dlterm" id="conditional_functions__zeroifnull">
ZEROIFNULL(type numeric_expr)
</dt>
<dd class="dd">
<strong class="ph b">Purpose:</strong> Returns 0 if the numeric expression evaluates to
<code class="ph codeph">NULL</code>, otherwise returns the result of the expression.
<p class="p">
<strong class="ph b">Usage notes:</strong> Used to avoid unexpected results due to unexpected propagation
of <code class="ph codeph">NULL</code> values in numeric calculations. Serves as shorthand for a
more elaborate <code class="ph codeph">CASE</code> expression, to simplify porting SQL with vendor
extensions to Impala.
</p>
<p class="p">
<strong class="ph b">Return type:</strong> Same type as the input argument
</p>
<p class="p">
<strong class="ph b">Added in:</strong> Impala 1.3.0
</p>
</dd>
</dl>
</div>
<div class="related-links">
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_functions.html">Impala Built-In Functions</a></div>
</div>
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