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<?xml version="1.0" encoding="utf-8"?>
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<meta name="keywords" content="without operators, expression,
with arithmetic operators, arithmetic, operators, arithmetic operators,
prefix operator, plus, unary, minus, infix operators, multiplication operator,
subtraction operator, division operator, exponentiation operator, * (multiply),
** (exponentiation), / (divide), - (subtraction), + (addition), integer operands,
integer, operand, decimal operands, numeric operands, decimal, numeric,
in results of arithmetic operations, scale of data, decimal data,
floating-point operands, floating point, distinct type operands, distinct type,
with concatenation operator, concatenation operator (CONCAT),
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<title>Expressions</title>
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<a name="ch2expr"></a>
<h2 id="ch2expr"><a href="rbafzmst02.htm#ToC_250">Expressions</a></h2>
<p>An expression specifies a value.</p>
<a href="rbafzmstch2expr.htm#synexpressions"><img src="c.gif" alt="Click to skip syntax diagram" /></a>
<a name="wq335"></a>
<div class="fignone" id="wq335">
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn20.htm"
border="0" /></span><a href="#skipsyn-19"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a> .-operator-------------------------.
V |
>>---+-----+--+-<span class="italic">function</span>------------+-+------------------------>&lt;
+-&nbsp;+&nbsp;-+ +-<span class="italic">(expression)</span>--------+
'-&nbsp;-&nbsp;-' +-<span class="italic">constant</span>------------+
+-<span class="italic">column-name</span>---------+
+-<span><span class="italic">variable</span></span>------------+
+-<span class="italic">special-register</span>----+
+-<span><span class="italic">(scalar-fullselect)</span></span>-+
+-<span class="italic">labeled-duration</span>----+
+-<span class="italic">case-expression</span>-----+
+-<span class="italic">cast-specification</span>--+
+-<span><span class="italic">OLAP-specification</span></span>--+
'-<span class="italic">sequence-reference</span>--'
</pre>
<a name="skipsyn-19" id="skipsyn-19"></a>
<p><span class="bold">operator:</span></p>
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn21.htm"
border="0" /></span><a href="#skipsyn-20"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>>>-+-CONCAT-+-------------------------------------------------->&lt;
+-&nbsp;||&nbsp;----+
+-&nbsp;/&nbsp;----+
+-&nbsp;*&nbsp;----+
+-&nbsp;**&nbsp;---+
+-&nbsp;+&nbsp;----+
'-&nbsp;-&nbsp;----'
</pre>
<a name="skipsyn-20" id="skipsyn-20"></a>
<a name="labdur"></a>
<p id="labdur"><span class="bold">labeled-duration:</span></p>
<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn22.htm"
border="0" /></span><a href="#skipsyn-21"><img src="c.gif" alt="Skip visual syntax diagram"
border="0" /></a>>>-+-<span class="italic">function</span>-----+--+-YEAR---------+-------------------------->&lt;
+-<span class="italic">(expression)</span>-+ +-YEARS--------+
+-<span class="italic">constant</span>-----+ +-MONTH--------+
+-<span class="italic">column-name</span>--+ +-MONTHS-------+
'-<span><span class="italic">variable</span></span>-----' +-DAY----------+
+-DAYS---------+
+-HOUR---------+
+-HOURS--------+
+-MINUTE-------+
+-MINUTES------+
+-SECOND-------+
+-SECONDS------+
+-MICROSECOND--+
'-MICROSECONDS-'
</pre>
<a name="skipsyn-21" id="skipsyn-21"></a></div>
<a name="synexpressions"></a>
<h3 id="synexpressions"><a href="rbafzmst02.htm#ToC_251">Without operators</a></h3>
<p><a id="idx655" name="idx655"></a></p>
<p>If no operators are used, the result of the expression is the specified
value.</p>
<a name="wq336"></a>
<h4 id="wq336">Example</h4>
<pre class="xmp"> SALARY :SALARY 'SALARY' <span class="bold">MAX(</span>SALARY<span class="bold">)</span></pre>
<a name="wq337"></a>
<h3 id="wq337"><a href="rbafzmst02.htm#ToC_253">With arithmetic operators</a></h3><a id="idx656" name="idx656"></a><a id="idx657" name="idx657"></a><a id="idx658" name="idx658"></a><a id="idx659" name="idx659"></a><a id="idx660" name="idx660"></a><a id="idx661" name="idx661"></a><a id="idx662" name="idx662"></a><a id="idx663" name="idx663"></a><a id="idx664" name="idx664"></a><a id="idx665" name="idx665"></a><a id="idx666" name="idx666"></a><a id="idx667" name="idx667"></a><a id="idx668" name="idx668"></a><a id="idx669" name="idx669"></a><a id="idx670" name="idx670"></a><a id="idx671" name="idx671"></a><a id="idx672" name="idx672"></a>
<p>If arithmetic operators are used, the result of the expression is a number
derived from the application of the operators to the values of the operands.</p>
<p>If any operand can be null, the result can be null. If any operand
has the null value, the result of the expression is the null value.</p>
<p>If one operand of an arithmetic operator is numeric, the other operand
can be a string. The string is first converted to the data type of the numeric
operand and must contain a valid string representation of a number.</p>
<p>The prefix operator + (<span class="italic">unary plus</span>) does not change
its operand. The prefix operator - (<span class="italic">unary minus</span>) reverses
the sign of a nonzero operand. If the data type of A is small integer, the
data type of - A is large integer. The first character of the token following
a prefix operator must not be a plus or minus sign.</p>
<p>The <span class="italic">infix operators</span>, +, -, *, /, and **, specify
addition, subtraction, multiplication, division, and exponentiation, respectively.
The value of the second operand of division must not be zero.</p>
<p>In COBOL, blanks must precede and follow a minus sign to avoid any ambiguity
with COBOL host variable names (which allow use of a dash).</p>
<p>The result of an exponentiation (**) operator is a double-precision floating-point
number. The result of the other operators depends on the type of the operand.</p>
<p>Operands with a NUMERIC data type are converted to DECIMAL operands
prior to performing the arithmetic operation.</p>
<a name="wq338"></a>
<h4 id="wq338">Two integer operands</h4><a id="idx673" name="idx673"></a><a id="idx674" name="idx674"></a>
<p>If both operands of an arithmetic operator are integers with zero scale,
the operation is performed in binary, and the result is a large integer unless
either (or both) operand is a big integer, in which case the result is a big
integer. Any remainder of division is lost. The result of an integer arithmetic
operation (including unary minus) must be within the range of large integers.
If either integer operand has nonzero scale, it is converted to a decimal
operand with the same precision and scale.</p>
<a name="wq339"></a>
<h4 id="wq339">Integer and decimal operands</h4><a id="idx675" name="idx675"></a><a id="idx676" name="idx676"></a><a id="idx677" name="idx677"></a><a id="idx678" name="idx678"></a><a id="idx679" name="idx679"></a><a id="idx680" name="idx680"></a>
<p>If one operand is an integer with zero scale and the other is decimal,
the operation is performed in decimal using a temporary copy of the integer
that has been converted to a decimal number with precision and scale 0 as
defined in the following table:</p>
<a name="wq340"></a>
<table id="wq340" width="100%" summary="" border="1" frame="border" rules="all">
<thead valign="bottom">
<tr>
<th id="wq341" width="50%" align="left" valign="bottom"><span class="bold">Operand</span></th>
<th id="wq342" width="50%" align="left" valign="bottom"><span class="bold">Precision of Decimal
Copy</span></th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq341">Column or variable: big integer</td>
<td align="left" valign="top" headers="wq342">19</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq341">Column or variable: large integer</td>
<td align="left" valign="top" headers="wq342">11</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq341">Column or variable: small integer</td>
<td align="left" valign="top" headers="wq342">5</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq341">Constant (including leading zeros)</td>
<td align="left" valign="top" headers="wq342">Same as the number of digits in the constant</td>
</tr>
</tbody>
</table>
<p>If one operand is an integer with nonzero scale, it is first converted
to a decimal operand with the same precision and scale.</p>
<a name="wq343"></a>
<h4 id="wq343">Two decimal operands</h4><a id="idx681" name="idx681"></a><a id="idx682" name="idx682"></a><a id="idx683" name="idx683"></a><a id="idx684" name="idx684"></a><a id="idx685" name="idx685"></a>
<p>If both operands are decimal, the operation is performed in decimal. The
result of any decimal arithmetic operation is a decimal number with a precision
and scale that are dependent on the operation and the precision and scale
of the operands. If the operation is addition or subtraction and the operands
do not have the same scale, the operation is performed with a temporary copy
of one of the operands. The copy of the shorter operand is extended with trailing
zeros so that its fractional part has the same number of digits as the longer
operand.</p>
<p>Unless specified otherwise, all functions and operations that accept decimal
numbers allow a precision of up to 63 digits. The result of a decimal operation
must not have a precision greater than 63.</p>
<a name="decarithmetic"></a>
<h4 id="decarithmetic">Decimal arithmetic in SQL</h4><a id="idx686" name="idx686"></a>
<p>The following formulas define the precision and scale of the result of
decimal operations in SQL. The symbols <span class="italic">p</span> and <span class="italic">s</span> denote the precision
and scale of the first operand and the symbols <span class="italic">p</span>'
and <span class="italic">s</span>' denote the precision and scale of the second
operand.</p>
<p>The symbol <span class="italic">mp</span> denotes the maximum precision. The
value of <span class="italic">mp</span> is 63 if:</p>
<ul>
<li>either w or y is greater than 31, or</li>
<li>a value of 63 was explicitly specified for the maximum precision.</li></ul><p class="indatacontent">Otherwise, the value of <span class="italic">mp</span> is 31.</p>
<p>The symbol <span class="italic">ms</span> denotes the maximum scale.
The default value of <span class="italic">ms</span> is 31. <span class="italic">ms</span> can be explicitly set to any number from 0 to the maximum precision.</p>
<p>The symbol <span class="italic">mds</span> denotes the minimum divide
scale. The default value of <span class="italic">mds</span> is 0. <span class="italic">mds</span> can be explicitly set to any number from 0 to the maximum scale.</p>
<p>The maximum precision, maximum scale, and minimum divide scale
can be explicitly specified on the DECRESULT parameter of the CRTSQLxxx command,
RUNSQLSTM command, or SET OPTION statement. They can also be specified in
ODBC data sources, JDBC properties, OLE DB properties, .NET properties.</p>
<a name="wq344"></a>
<h5 id="wq344">Addition and subtraction</h5>
<p>The scale of the result of addition and subtraction is max (<var class="pv">s,s'</var>).
The precision is min(<span class="italic">mp</span>,max(<var class="pv">p-s,p'-s'</var>) +max(<var class="pv">s,s'</var>)+1).</p>
<a name="wq345"></a>
<h5 id="wq345">Multiplication</h5>
<p>The precision of the result of multiplication is min (<span class="italic">mp</span>,<var class="pv">p</var>+<var class="pv">p'</var>) and the scale is min(<span class="italic">ms</span>,<var class="pv">s</var>+<var class="pv">s'</var>).</p>
<a name="wq346"></a>
<h5 id="wq346">Division</h5>
<p>The precision of the result of division is (<var class="pv">p</var>-<var class="pv">s</var>+<var class="pv">s'</var>) + max(<var class="pv">mds</var>, min(<var class="pv">ms</var>, <var class="pv">mp</var> - (<var class="pv">p</var>-<var class="pv">s</var>+<var class="pv">s'</var>) ) ). The scale is max(<span class="italic">mds</span>, min(<var class="pv">ms</var>, <var class="pv">mp</var> - (<var class="pv">p</var>-<var class="pv">s</var>+<var class="pv">s'</var>) ) ). The scale
must not be negative.</p>
<a name="wq347"></a>
<h4 id="wq347">Floating-point operands</h4><a id="idx687" name="idx687"></a><a id="idx688" name="idx688"></a>
<p>If either operand of an arithmetic operator is floating point, the operation
is performed in floating point. The operands are first converted to double-precision
floating-point numbers, if necessary. Thus, if any element of an expression
is a floating-point number, the result of the expression is a double-precision
floating-point number.</p>
<p>An operation involving a floating-point number and an integer is performed
with a temporary copy of the integer converted to double-precision floating
point. An operation involving a floating-point number and a decimal number
is performed with a temporary copy of the decimal number that has been converted
to double-precision floating point. The result of a floating-point operation
must be within the range of floating-point numbers.</p>
<p>The order in which floating-point operands (or arguments to functions)
are processed can slightly affect results because floating-point operands
are approximate representations of real numbers. Since the order in which
operands are processed may be implicitly modified by the optimizer (for example,
the optimizer may decide what degree of parallelism to use and what access
plan to use), an application should not depend on the results being precisely
the same each time an SQL statement is executed that uses floating-point operands.</p>
<a name="wq348"></a>
<h4 id="wq348">Distinct types as operands</h4><a id="idx689" name="idx689"></a><a id="idx690" name="idx690"></a>
<p>A distinct type cannot be used with arithmetic operators even if its source data
type is numeric. To perform an arithmetic operation, create a function with
the arithmetic operator as its source. For example, if there were distinct
types INCOME and EXPENSES, both of which had DECIMAL(8,2) data types, then
the following user-defined function, REVENUE, could be used to subtract one
from the other.</p>
<pre class="xmp"> <span class="bold">CREATE FUNCTION </span>REVENUE <span class="bold">(</span> INCOME, EXPENSES <span class="bold">)</span>
<span class="bold">RETURNS DECIMAL(</span>8,2<span class="bold">) SOURCE</span> "-" <span class="bold">( DECIMAL, DECIMAL)</span></pre>
<p>Alternately, the - (minus) operator could be overloaded using a user-defined
function to subtract the new data types. </p>
<pre class="xmp"> <span class="bold">CREATE FUNCTION</span> "-" <span class="bold">(</span> INCOME, EXPENSES <span class="bold">)</span>
<span class="bold">RETURNS DECIMAL(</span>8,2<span class="bold">) SOURCE</span> "-" <span class="bold">( DECIMAL, DECIMAL)</span></pre>
<a name="wtco"></a>
<h3 id="wtco"><a href="rbafzmst02.htm#ToC_263">With the concatenation operator</a></h3><a id="idx691" name="idx691"></a><a id="idx692" name="idx692"></a><a id="idx693" name="idx693"></a><a id="idx694" name="idx694"></a>
<p>If the concatenation operator (CONCAT or ||) is used, the result of the
expression is a string. </p>
<p>The operands of concatenation must be compatible strings or numeric data
types. The operands must not be distinct types. If a numeric operand is specified,
it is CAST to the equivalent character string prior to concatenation. Note
that a binary string cannot be concatenated with a character string, including
character strings defined as FOR BIT DATA.</p>
<p>The data type of the result is determined by the data types of the operands.
The data type of the result is summarized in the following table:</p>
<a name="wq349"></a>
<table id="wq349" width="100%" summary="" border="1" frame="border" rules="rows">
<caption>Table 23. Result Data Types With Concatenation</caption>
<thead valign="bottom">
<tr>
<th id="wq350" width="25%" align="left" valign="bottom">If one operand column is ...</th>
<th id="wq351" width="25%" align="left" valign="bottom">And the other operand is ...</th>
<th id="wq352" width="50%" align="left" valign="bottom">The data type of the result column is
...</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq350">DBCLOB(x)</td>
<td align="left" valign="top" headers="wq351">CHAR(y)* or VARCHAR(y)*
or CLOB(y)* or GRAPHIC(y) or VARGRAPHIC(y) or DBCLOB(y)</td>
<td align="left" valign="top" headers="wq352">DBCLOB(z) where z = MIN(x + y, maximum length
of a DBCLOB)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">VARGRAPHIC(x)</td>
<td align="left" valign="top" headers="wq351">CHAR(y)* or VARCHAR(y)*
or GRAPHIC(y) or VARGRAPHIC(y)</td>
<td align="left" valign="top" headers="wq352">VARGRAPHIC(z) where z = MIN(x + y, maximum
length of a VARGRAPHIC)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">GRAPHIC(x)</td>
<td align="left" valign="top" headers="wq351">CHAR(y)* mixed data</td>
<td align="left" valign="top" headers="wq352">VARGRAPHIC(z) where z = MIN(x + y, maximum
length of a VARGRAPHIC)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">GRAPHIC(x)</td>
<td align="left" valign="top" headers="wq351">CHAR(y)* SBCS data or GRAPHIC(y)</td>
<td align="left" valign="top" headers="wq352">GRAPHIC(z) where z = MIN(x + y, maximum length
of a GRAPHIC)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">CLOB(x)*</td>
<td align="left" valign="top" headers="wq351">GRAPHIC(y) or VARGRAPHIC(y)</td>
<td align="left" valign="top" headers="wq352">DBCLOB(z) where z = MIN(x + y, maximum length
of a DBCLOB)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">VARCHAR(x)*</td>
<td align="left" valign="top" headers="wq351">GRAPHIC(y)</td>
<td align="left" valign="top" headers="wq352">VARGRAPHIC(z) where z = MIN(x + y, maximum
length of a VARGRAPHIC)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">CLOB(x)</td>
<td align="left" valign="top" headers="wq351">CHAR(y) or VARCHAR(y) or CLOB(y)</td>
<td align="left" valign="top" headers="wq352">CLOB(z) where z = MIN(x + y, maximum length
of a CLOB)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">VARCHAR(x)</td>
<td align="left" valign="top" headers="wq351">CHAR(y) or VARCHAR(y)</td>
<td align="left" valign="top" headers="wq352">VARCHAR(z) where z = MIN(x + y, maximum length
of a VARCHAR)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">CHAR(x) mixed data</td>
<td align="left" valign="top" headers="wq351">CHAR(y)</td>
<td align="left" valign="top" headers="wq352">VARCHAR(z) where z = MIN(x + y, maximum length
of a VARCHAR)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">CHAR(x) SBCS data</td>
<td align="left" valign="top" headers="wq351">CHAR(y)</td>
<td align="left" valign="top" headers="wq352">CHAR(z) where z = MIN(x + y, maximum length
of a CHAR)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">BLOB(x)</td>
<td align="left" valign="top" headers="wq351">BINARY(y) or VARBINARY(y) or BLOB(y)</td>
<td align="left" valign="top" headers="wq352">BLOB(z) where z = MIN(x + y, maximum length
of a BLOB)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">VARBINARY(x)</td>
<td align="left" valign="top" headers="wq351">BINARY(y) or VARBINARY(y)</td>
<td align="left" valign="top" headers="wq352">VARBINARY(z) where z = MIN(x + y, maximum
length of a VARBINARY)</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq350">BINARY(x)</td>
<td align="left" valign="top" headers="wq351">BINARY(y)</td>
<td align="left" valign="top" headers="wq352">BINARY(z) where z = MIN(x + y, maximum length
of a BINARY)</td>
</tr>
<tr>
<td colspan="3" headers="wq350 wq351 wq352">
<a name="wq353"></a>
<div class="notetitle" id="wq353">Note:</div>
<div class="notebody">
<p>* Character strings are
only allowed when the other operand is a graphic string if the graphic string
is UTF-16 or UCS-2.</p></div></td>
</tr>
</tbody>
</table>
<a name="wq354"></a>
<table id="wq354" width="100%" summary="" border="1" frame="border" rules="rows">
<caption>Table 24. Result Encoding Schemes With Concatenation</caption>
<thead valign="bottom">
<tr>
<th id="wq355" width="25%" align="left" valign="bottom">If one operand column is ...</th>
<th id="wq356" width="25%" align="left" valign="bottom">And the other operand is ...</th>
<th id="wq357" width="50%" align="left" valign="bottom">The data type of the result column is
...</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" valign="top" headers="wq355">Unicode data</td>
<td align="left" valign="top" headers="wq356">Unicode data or DBCS or mixed or SBCS data</td>
<td align="left" valign="top" headers="wq357">Unicode data</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq355">DBCS data</td>
<td align="left" valign="top" headers="wq356">DBCS data</td>
<td align="left" valign="top" headers="wq357">DBCS data</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq355">bit data</td>
<td align="left" valign="top" headers="wq356">mixed or SBCS or bit data</td>
<td align="left" valign="top" headers="wq357">bit data</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq355">mixed data</td>
<td align="left" valign="top" headers="wq356">mixed or SBCS data</td>
<td align="left" valign="top" headers="wq357">mixed data</td>
</tr>
<tr>
<td align="left" valign="top" headers="wq355">SBCS data</td>
<td align="left" valign="top" headers="wq356">SBCS data</td>
<td align="left" valign="top" headers="wq357">SBCS data</td>
</tr>
</tbody>
</table>
<p>If the sum of the lengths of the operands exceeds the maximum length attribute
of the resulting data type:</p>
<ul>
<li>The length atttribute of the result is the maximum length of the resulting
data type.<sup class="fn"><a id="wq358" name="wq358" href="rbafzmstch2expr.htm#wq359">36</a></sup></li>
<li>If only blanks are truncated no warning or error occurs.</li>
<li>If non-blanks are truncated, an error occurs.</li></ul>
<p>If either operand can be null, the result can be null, and if either is
null, the result is the null value. Otherwise, the result consists of the
first operand string followed by the second.</p>
<p>With mixed data this result will not have redundant shift codes &quot;at the
seam&quot;. Thus, if the first operand is a string ending with a &quot;shift-in&quot; character (<span class="hex">X'0F'</span>), while the second operand is a character string
beginning with a &quot;shift-out&quot; character (<span class="hex">X'0E'</span>), these two bytes
are eliminated from the result.</p>
<p>The actual length of the result is the sum of the lengths of the operands
unless redundant shifts are eliminated; in which case, the actual length is
two less than the sum of the lengths of the operands.</p>
<p>The CCSID of the result is determined by the CCSID of the operands as explained
under <a href="rbafzmstuuall.htm#uuall">Conversion rules for operations that combine strings</a>. Note that as a result of these rules: </p>
<ul>
<li>If any operand is bit data, the result is bit data.</li>
<li>If one operand is mixed data and the other is SBCS data, the result is
mixed data. However, this does not necessarily mean that the result is well-formed
mixed data.</li></ul>
<a name="wq360"></a>
<h4 id="wq360">Example</h4>
<p>Concatenate the column FIRSTNME with a blank and the column LASTNAME. </p>
<pre class="xmp"> FIRSTNME <span class="bold">CONCAT</span> ' ' <span class="bold">CONCAT</span> LASTNAME</pre>
<a name="scalarsubs"></a>
<h3 id="scalarsubs"><a href="rbafzmst02.htm#ToC_265">Scalar fullselect</a></h3><a id="idx695" name="idx695"></a><a id="idx696" name="idx696"></a>
<p>A scalar fullselect as supported in an expression is a fullselect,
enclosed in parentheses, that returns a single row consisting of a single
column value. If the fullselect does not return a row, the result of the expression
is the null value. If the select list element is an expression that is simply
a column name, the result column name is based on the name of the column.
See <a href="rbafzmstmark.htm#mark">fullselect</a> for more information.</p>
<p>A scalar fullselect is not allowed if the query specifies:</p>
<ul>
<li>lateral correlation,</li>
<li>a sort sequence,</li>
<li>an operation that requires CCSID conversion,</li>
<li>a UTF-8 or UTF-16 argument in a CHARACTER_LENGTH, POSITION, or SUBSTRING
scalar function,</li>
<li>a distributed table,</li>
<li>a table with a read trigger, or</li>
<li>a logical file built over multiple physical file members.</li></ul><a id="idx697" name="idx697"></a>
<p>A scalar subselect as supported in an expression is a subselect,
enclosed in parentheses, that returns a single row consisting of a single
column value. If the subselect does not return a row, the result of the expression
is the null value. If the select list element is an expression that is simply
a column name, the result column name is based on the name of the column.
See <a href="rbafzmstmark.htm#mark">fullselect</a> for more information.</p>
<a name="dtdur"></a>
<h3 id="dtdur"><a href="rbafzmst02.htm#ToC_266">Datetime operands and durations</a></h3><a id="idx698" name="idx698"></a><a id="idx699" name="idx699"></a><a id="idx700" name="idx700"></a><a id="idx701" name="idx701"></a>
<p>Datetime values can be incremented, decremented, and subtracted. These
operations may involve decimal numbers called <span class="italic">durations</span>. A <span class="italic">duration</span> is a positive or negative number
representing an interval of time. There are four types of durations: </p>
<dl>
<dt class="bold">Labeled durations (see <span><a href="rbafzmstch2expr.htm#labdur">diagram</a> on
page 125</span>)</dt>
<dd>A <span class="italic">labeled duration</span> represents a specific unit of time as
expressed by a number (which can be the result of an expression) followed
by one of the seven duration keywords: YEARS, MONTHS, DAYS, HOURS, MINUTES,
SECONDS, or MICROSECONDS<sup class="fn"><a href="rbafzmstch2expr.htm#fn17">37</a></sup>. The number specified is converted
as if it were assigned to a DECIMAL(15,0) number.
<p>A labeled duration can
only be used as an operand of an arithmetic operator in which the other operand
is a value of data type DATE, TIME, or TIMESTAMP. Thus, the expression HIREDATE
+ 2 MONTHS + 14 DAYS is valid whereas the expression HIREDATE + (2 MONTHS
+ 14 DAYS) is not. In both of these expressions, the labeled durations are
2 MONTHS and 14 DAYS.</p>
</dd>
<dt class="bold">Date duration</dt><a id="idx702" name="idx702"></a><a id="idx703" name="idx703"></a>
<dd>A <span class="italic">date duration</span> represents a number of years,
months, and days, expressed as a DECIMAL(8,0) number. To be properly interpreted,
the number must have the format <span class="italic">yyyymmdd</span>, where <span class="italic">yyyy</span> represents the number of years, <span class="italic">mm</span> the number of months, and <span class="italic">dd</span> the number of
days. The result of subtracting one date value from another, as in the expression
HIREDATE - BRTHDATE, is a date duration.
</dd>
<dt class="bold">Time duration</dt><a id="idx704" name="idx704"></a><a id="idx705" name="idx705"></a>
<dd>A <span class="italic">time duration</span> represents a number of hours,
minutes, and seconds, expressed as a DECIMAL(6,0) number. To be properly interpreted,
the number must have the format <span class="italic">hhmmss</span> where <span class="italic">hh</span> represents the number of hours, <span class="italic">mm</span> the number
of minutes, and <span class="italic">ss</span> the number of seconds. The result
of subtracting one time value from another is a time duration.
</dd>
<dt class="bold">Timestamp duration</dt><a id="idx706" name="idx706"></a><a id="idx707" name="idx707"></a>
<dd>A <span class="italic">timestamp duration</span> represents a number of
years, months, days, hours, minutes, seconds, and microseconds, expressed
as a DECIMAL(20,6) number. To be properly interpreted, the number must have
the format <span class="italic">yyyymmddhhmmsszzzzzz,</span> where <span class="italic">yyyy, mm, dd, hh, mm, ss, <span class="base">and</span> zzzzzz</span> represent,
respectively, the number of years, months, days, hours, minutes, seconds,
and microseconds. The result of subtracting one timestamp value from another
is a timestamp duration.
</dd>
</dl>
<hr /><div class="fnnum"><a id="wq359" name="wq359" href="rbafzmstch2expr.htm#wq358">36</a>.</div>
<div class="fntext">If the expression is in the select-list, the length attribute
may be further reduced in order to fit within the maximum record size. For
more information, see <a href="rbafzmsthctabl.htm#maxrcd">Maximum row sizes</a>.</div><div class="fnnum"><a id="fn17" name="fn17">37</a>.</div>
<div class="fntext">Note that the singular form of these keywords is also
acceptable: YEAR, MONTH, DAY, HOUR, MINUTE, SECOND, and MICROSECOND.</div>
<br />
<hr /><br />
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