📄 comparisonoperators.htm

📁 Absolute Database 5.12 src. Absolute Database lets you forget the Borland Database Engine (BDE). Th
💻 HTM
字号:
<html>
<head>
   <title>Comparison Operators</title>
</head>

<!--#include virtual="/inc/header.php"-->


<table width="100%" border="0" cellspacing="0" cellpadding="2" bgcolor="#FFFFFF">
  <tr>
    <td align="left">
      
<span style="font-family:Helvetica,Arial; font-size:12pt; color:#000000"><b>Comparison Operators
<br>
</b></span>
    </td>
    <td align="right">
     <font face="Arial" size="2">
     <a href="namingconventions.htm">Previous</a>&nbsp;
     <a href="overview.htm">Top</a>&nbsp;
     <a href="logicaloperators.htm">Next</a>
     </font>
    </td>
  </tr>
</table>
<br><br>



<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">
<br>
Comparison operators are used with character (including Memo), numeric, or date/time data and can be used in the WHERE or HAVING clause of a query. Comparison operators evaluate to a Boolean data type; they return TRUE, FALSE or NULL based on the outcome of the tested condition.
<br>

<br>
The comparison operators supported by Absolute Database are listed in the table below:
<br>

<br>
<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><table border="0" cellpadding="1"><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><b><u>Operator</u></b>
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><b><u>Description</u></b>
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><b><u>Examples</u></b>
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">=
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Equal
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Name = 'Smith'
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">&lt;&gt;
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Not equal to
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">State &lt;&gt; 'CA'
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">&gt;
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Greater than
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">BillDate &gt; '01 Jan 2002'
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">&lt;
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Less than
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Price &lt; 95.5
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">&gt;=
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Greater than or equal to
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">ID &gt;= 100
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">&lt;=
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Less than or equal to
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Code &lt;= 'T'
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">BETWEEN <i>expr1</i> AND <i>expr2</i>
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Tests range of values<span style="font-family:Times New Roman; font-size:12pt; color:#000000">
<br>
</span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">
<br>
</span></span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">BETWEEN 
<br>
'01 Jan 1995' 
<br>
AND 
<br>
'31 Dec 1995'
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[NOT] IN (<i>list | subquery</i>)
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Tests whether column is equal to any member in list
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Color IN ('Blue', 'Red', 'Green')
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">IS [NOT] NULL
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Tests whether contents of column is null
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Fax IS NULL
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[NOT] LIKE <i>pattern </i>[ESCAPE <i>escape_char</i>]
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Performs pattern matching ( % means any string of zero or more characters; _ (underscore) 
<br>
means any single character ). Escape character is used to search for a % or a _ character.
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Name LIKE 'John%'; CustNo LIKE '100_'; Progress LIKE '%0\%' ESCAPE '\'
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">ANY (SOME)
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Tests whether one or more rows in the result set of a subquery meet the specified condition.
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Color = ANY (subquery)
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">ALL
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Tests whether all rows in the result set of a subquery meet the specified condition.
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Salary &gt; ALL (subquery)
<br>
</span></td></tr><tr><td align="left" valign="top" width="116">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[NOT] EXISTS
<br>
</span></td><td align="left" valign="top" width="189">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Tests whether a subquery returns any results.
<br>
</span></td><td align="left" valign="top" width="142">
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">EXISTS (subquery)
<br>
</span></td></tr></table>
&nbsp;<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">
&nbsp;<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"></span></td></tr></table><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">
<br>
</span></span>

<!--#include virtual="/inc/footer.php"--> 
</html>
⌨️ 快捷键说明

复制代码 Ctrl + C
搜索代码 Ctrl + F
全屏模式 F11
切换主题 Ctrl + Shift + D
显示快捷键 ?
增大字号 Ctrl + =
减小字号 Ctrl + -