📄 selectstatement.htm
字号:
<html>
<head>
<title>SELECT Command</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>SELECT Command
<br>
</b></span>
</td>
<td align="right">
<font face="Arial" size="2">
<a href="conditionalexpressions.htm">Previous</a>
<a href="overview.htm">Top</a>
<a href="subqueries.htm">Next</a>
</font>
</td>
</tr>
</table>
<br><br>
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">
<br>
SELECT is used to retrieve rows selected from one or more tables.
<br>
<span style="font-family:Helvetica,Arial; font-size:10pt; color:#010100"><a href=subqueries.htm>Correlated and uncorrelated subqueries</a></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><span style="font-family:Helvetica,Arial; font-size:10pt; color:#010100"> are supported.
<br>
<br>
</span></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><span style="font-family:Helvetica,Arial; font-size:10pt; color:#010100"><b>Brief Syntax</b></span></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><span style="font-family:Helvetica,Arial; font-size:10pt; color:#010100">
<br>
</span></span><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"><span style="font-family:Helvetica,Arial; font-size:4pt; color:#010100">
<br>
</span></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">SELECT
<br>
<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[ ALL | DISTINCT ]
<br>
</span></span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[ TOP <i>row_count</i> [, <i>offset</i> ] ]
<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></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"><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">* | <i>column_reference</i> | <i>select_expr</i> [ [ AS ] <i>column_alias</i> ] [, ...]
<br>
</span></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"><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[ INTO <i>output_table</i> ]
<br>
</span></span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></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"><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">FROM <i>from_item</i> [, ...]
<br>
</span></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"><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[ WHERE <i>condition</i> ]
<br>
</span></span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[ GROUP BY { <i>column_name</i> | <i>expression</i> } [, ...] ]
<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[ HAVING <i>condition</i> ]
<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[ { UNION | INTERSECT | EXCEPT } [ ALL ] [ <span style="font-family:Helvetica,Arial; font-size:10pt; color:#010100">CORRESPONDING [ BY (</span></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><span style="font-family:Helvetica,Arial; font-size:10pt; color:#010100"><i>column_list</i></span></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><span style="font-family:Helvetica,Arial; font-size:10pt; color:#010100">) ] ] </span></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">SELECT ... ]
<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[ ORDER BY { <i>unsigned_integer</i> | <i>column_name</i> } [ ASC | DESC ] [, ...] ] </span><span style="font-family:Times New Roman; font-size:12pt; color:#000000">
<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Times New Roman; font-size:12pt; color:#000000"></span></td></tr></table><span style="font-family:Times New Roman; font-size:12pt; color:#000000"></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">
<br>
where <i>from_item </i>can be one of:
<br>
</span><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000">
<br>
<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">[ MEMORY ] ["<i>database_file_name".</i>] <i>table_name</i> [ [ AS ] <i>table_alias </i>] [ PASSWORD <i>database_password </i>]
<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><i>select</i> ... [ [ AS ] <i>table_alias </i>]
<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><i>from_item</i> [ NATURAL ] <i>join_type</i> <i>from_item</i> [ ON <i>join_condition</i> | USING ( <i>join_column</i> [, ...] ) ] [ [ AS ] <i>table_alias </i>]
<br>
</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="28"></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>
<b>Description
<br>
</b></span><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000">
<br>
</span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">SELECT retrieves rows from one or more tables.
<br>
</span><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000">
<br>
</span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Using the <b>ALL</b> keyword allows duplicate records to appear in the results of a SELECT query. This is the default.
<br>
Using the <b>DISTINCT</b> keyword prevents duplicate records from appearing in the results of a SELECT query.
<br>
<br>
The <b>TOP</b> clause can be used to constrain the number of rows returned by the SELECT statement. TOP takes one or two integer arguments. The first argument specifies the maximum number of rows to return, and the second specifies the offset of the first row to return. The offset of the initial row is 1 (not 0):
<br>
</span><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000">
<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:4pt; color:#000000"></span></span><span style="font-family:Courier New; font-size:8pt; color:#000000">SELECT TOP 10,20 * FROM employee</span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"> </span><span style="font-family:Courier New; font-size:8pt; color:#000000">/* returns rows 20-29 */
<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:Courier New; font-size:8pt; color:#000000"></span></td></tr></table><span style="font-family:Courier New; font-size:8pt; color:#000000"><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Courier New; font-size:8pt; color:#000000">
⌨️ 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 + -