📄 lang_expr.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"><html><head><title>SQLite Query Language: expression</title><style type="text/css">body { margin: auto; font-family: "Verdana" "sans-serif"; padding: 8px 1%;}a { color: #45735f }a:visited { color: #734559 }.logo { position:absolute; margin:3px; }.tagline { float:right; text-align:right; font-style:italic; width:240px; margin:12px; margin-top:58px;}.toolbar { font-variant: small-caps; text-align: center; line-height: 1.6em; margin: 0; padding:1px 8px;}.toolbar a { color: white; text-decoration: none; padding: 6px 12px; }.toolbar a:visited { color: white; }.toolbar a:hover { color: #80a796; background: white; }.content { margin: 5%; }.content dt { font-weight:bold; }.content dd { margin-bottom: 25px; margin-left:20%; }.content ul { padding:0px; padding-left: 15px; margin:0px; }/* rounded corners */.se { background: url(images/se.png) 100% 100% no-repeat #80a796}.sw { background: url(images/sw.png) 0% 100% no-repeat }.ne { background: url(images/ne.png) 100% 0% no-repeat }.nw { background: url(images/nw.png) 0% 0% no-repeat }</style><meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head><body><div><!-- container div to satisfy validator --><a href="index.html"><img class="logo" src="images/SQLite.gif" alt="SQLite Logo" border="0"></a><div><!-- IE hack to prevent disappearing logo--></div><div class="tagline">Small. Fast. Reliable.<br>Choose any three.</div><table width=100% style="clear:both"><tr><td> <div class="se"><div class="sw"><div class="ne"><div class="nw"> <div class="toolbar"> <a href="about.html">About</a> <a href="sitemap.html">Sitemap</a> <a href="docs.html">Documentation</a> <a href="download.html">Download</a> <a href="copyright.html">License</a> <a href="news.html">News</a> <a href="http://www.sqlite.org/cvstrac/index">Developers</a> <a href="support.html">Support</a> </div></div></div></div></div></td></tr></table> <a href="lang.html"><h2>SQL As Understood By SQLite</h2></a><h3>expression</h3><table cellpadding="10"><tr><td align="right" valign="top"><i><font color="#ff3434">expr</font></i> ::=</td><td><b><font color="#2c2cf0"></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b><i><font color="#ff3434">binary-op</font></i><b><font color="#2c2cf0"> </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b>[<b><font color="#2c2cf0">NOT</font></b>]<b><font color="#2c2cf0"> </font></b><i><font color="#ff3434">like-op</font></i><b><font color="#2c2cf0"> </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b>[<b><font color="#2c2cf0">ESCAPE </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"></font></b>]<b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">unary-op</font></i><b><font color="#2c2cf0"> </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br><big>(</big> </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> <big>)</big> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">column-name</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">table-name</font></i><b><font color="#2c2cf0"> <big>.</big> </font></b><i><font color="#ff3434">column-name</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">database-name</font></i><b><font color="#2c2cf0"> <big>.</big> </font></b><i><font color="#ff3434">table-name</font></i><b><font color="#2c2cf0"> <big>.</big> </font></b><i><font color="#ff3434">column-name</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">literal-value</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">parameter</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">function-name</font></i><b><font color="#2c2cf0"> <big>(</big> </font></b><i><font color="#ff3434">expr-list</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"> <big>*</big> <big>)</big> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> ISNULL </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> NOTNULL </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b>[<b><font color="#2c2cf0">NOT</font></b>]<b><font color="#2c2cf0"> BETWEEN </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> AND </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b>[<b><font color="#2c2cf0">NOT</font></b>]<b><font color="#2c2cf0"> IN <big>(</big> </font></b><i><font color="#ff3434">value-list</font></i><b><font color="#2c2cf0"> <big>)</big> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b>[<b><font color="#2c2cf0">NOT</font></b>]<b><font color="#2c2cf0"> IN <big>(</big> </font></b><i><font color="#ff3434">select-statement</font></i><b><font color="#2c2cf0"> <big>)</big> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b>[<b><font color="#2c2cf0">NOT</font></b>]<b><font color="#2c2cf0"> IN </font></b>[<b><font color="#2c2cf0"></font></b><i><font color="#ff3434">database-name</font></i><b><font color="#2c2cf0"> <big>.</big></font></b>]<b><font color="#2c2cf0"> </font></b><i><font color="#ff3434">table-name</font></i><b><font color="#2c2cf0"> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b>[<b><font color="#2c2cf0">EXISTS</font></b>]<b><font color="#2c2cf0"> <big>(</big> </font></b><i><font color="#ff3434">select-statement</font></i><b><font color="#2c2cf0"> <big>)</big> </font></b><big>|</big><b><font color="#2c2cf0"><br>CASE </font></b>[<b><font color="#2c2cf0"></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"></font></b>]<b><font color="#2c2cf0"> </font></b>(<b><font color="#2c2cf0"> WHEN </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> THEN </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> </font></b>)+<b><font color="#2c2cf0"> </font></b>[<b><font color="#2c2cf0">ELSE </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"></font></b>]<b><font color="#2c2cf0"> END </font></b><big>|</big><b><font color="#2c2cf0"><br>CAST <big>(</big> </font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> AS </font></b><i><font color="#ff3434">type</font></i><b><font color="#2c2cf0"> <big>)</big> </font></b><big>|</big><b><font color="#2c2cf0"><br></font></b><i><font color="#ff3434">expr</font></i><b><font color="#2c2cf0"> COLLATE </font></b><i><font color="#ff3434">collation-name</font></i><b><font color="#2c2cf0"></font></b></td></tr><tr><td align="right" valign="top"><i><font color="#ff3434">like-op</font></i> ::=</td><td><b><font color="#2c2cf0">LIKE </font></b><big>|</big><b><font color="#2c2cf0"> GLOB </font></b><big>|</big><b><font color="#2c2cf0"> REGEXP </font></b><big>|</big><b><font color="#2c2cf0"> MATCH</font></b></td></tr></table><p>This section is different from the others. Most other sections ofthis document talks about a particular SQL command. This section doesnot talk about a standalone command but about "expressions" which are subcomponents of most other commands.</p><p>SQLite understands the following binary operators, in order fromhighest to lowest precedence:</p><blockquote><pre><font color="#2c2cf0"><big>||* / %+ -<< >> & |< <= > >== == != <> </big>INAND OR</font></pre></blockquote><p>Supported unary prefix operators are these:</p><blockquote><pre><font color="#2c2cf0"><big>- + ~ NOT</big></font></pre></blockquote><p>The COLLATE operator can be thought of as a unary postfixoperator. The COLLATE operator has the highest precedence.It always binds more tightly than any prefix unary operator orany binary operator.</p><p>The unary operator <font color="#2c2cf0"><big>+</big></font> is a no-op. It can be appliedto strings, numbers, or blobs and it always gives as its result thevalue of the operand.</p><p>Note that there are two variations of the equals and not equalsoperators. Equals can be either<font color="#2c2cf0"><big>=</big></font> or <font color="#2c2cf0"><big>==</big></font>.The non-equals operator can be either<font color="#2c2cf0"><big>!=</big></font> or <font color="#2c2cf0"><big><></big></font>.The <font color="#2c2cf0"><big>||</big></font> operator is "concatenate" - it joins togetherthe two strings of its operands.The operator <font color="#2c2cf0"><big>%</big></font> outputs the remainder of its left operand modulo its right operand.</p><p>The result of any binary operator is a numeric value, exceptfor the <font color="#2c2cf0"><big>||</big></font> concatenation operator which gives a stringresult.</p><a name="literal_value"></a><p>A literal value is an integer number or a floating point number.Scientific notation is supported. The "." character is always usedas the decimal point even if the locale setting specifies "," forthis role - the use of "," for the decimal point would result insyntactic ambiguity. A string constant is formed by enclosing thestring in single quotes ('). A single quote within the string canbe encoded by putting two single quotes in a row - as in Pascal.C-style escapes using the backslash character are not supported becausethey are not standard SQL.BLOB literals are string literals containing hexadecimal data andpreceded by a single "x" or "X" character. For example:</p><blockquote><pre>X'53514C697465'</pre></blockquote><p>A literal value can also be the token "NULL".</p><p>A parameter specifies a placeholder in the expression for a literalvalue that is filled in at runtime using the<a href="c3ref/bind_blob.html">sqlite3_bind()</a> APIs.⌨️ 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 + -