SherbyNet - /page/wikibook/entry.mu

Micron Document

<!DOCTYPE html>

<title>Update (SQL)</title>

</head>

Update (SQL)

</h1>

</header>

An <a href="SQL" title="SQL">SQL</a> UPDATE statement changes the data of one or more records in a <a href="Table_(database)" title="Table (database)">table</a>. Either all the rows can be updated, or a subset may be chosen using a <a href="Condition_(SQL)" title="Condition (SQL)">condition</a>.

The <code>UPDATE</code> statement has the following form:<a href="#cite_note-1">[1]</a>

<dl><dd><code>UPDATE</code> table_name <code>SET</code> column_name = value [, column_name = value ...] [<code>WHERE</code> condition]</dd></dl>

For the <code>UPDATE</code> to be successful, the user must have data manipulation privileges (<code>UPDATE</code> privilege) on the table or <a href="Column_(database)" title="Column (database)">column</a> and the updated value must not conflict with all the applicable constraints (such as <a href="Primary_key" title="Primary key">primary keys</a>, unique indexes, <a href="Check_Constraint" class="mw-redirect" title="Check Constraint"><code>CHECK</code> constraints</a>, and <a href="Null_(SQL)" title="Null (SQL)"><code>NOT NULL</code></a> constraints).

In some databases, such as <a href="PostgreSQL" title="PostgreSQL">PostgreSQL</a>, when a <a href="From_(SQL)" title="From (SQL)">FROM clause</a> is present, what essentially happens is that the target table is joined to the tables mentioned in the fromlist, and each output row of the join represents an update operation for the target table. When using FROM, one should ensure that the join produces at most one output row for each row to be modified. In other words, a target row shouldn't join to more than one row from the other table(s). If it does, then only one of the join rows will be used to update the target row, but which one will be used is not readily predictable.<a href="#cite_note-2">[2]</a>

Because of this indeterminacy, referencing other tables only within sub-selects is safer, though often harder to read and slower than using a join.

MySQL does not conform to ANSI standard.<a href="#cite_note-3">[3]</a>

<div class="mw-heading mw-heading2"><h2 id="Examples">Examples</h2></div>

Set the value of column C1 in table T to 1, only in those rows where the value of column C2 is "a".

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE T

SET C1 = 1

WHERE C2 = 'a'

</pre></div>

In table T, set the value of column C1 to 9 and the value of C3 to 4 for all rows for which the value of column C2 is "a".

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE T

SET C1 = 9,

C3 = 4

</pre></div>

Increase value of column C1 by 1 if the value in column C2 is "a".

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE T

</pre></div>

Prepend the value in column C1 with the string "text" if the value in column C2 is "a".

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE T

</pre></div>

Set the value of column C1 in table T1 to 2, only if the value of column C2 is found in the sublist of values in column C3 in table T2 having the column C4 equal to 0.

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE T1

SET C1 = 2

WHERE C2 IN ( SELECT C3

FROM T2

WHERE C4 = 0)

</pre></div>

One may also update multiple columns in a single update statement:

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE T

C2 = 2

</pre></div>

Complex conditions and JOINs are also possible:

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE T

SET A = 1

WHERE C1 = 1

AND C2 = 2

</pre></div>

Some databases allow the non-standard use of the FROM clause:

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE a

SET a.[updated_column] = updatevalue

FROM articles a

JOIN classification c

ON a.articleID = c.articleID

WHERE c.classID = 1

</pre></div>

Or on Oracle systems (assuming there is an index on classification.articleID):

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE

(

SELECT *

FROM articles

JOIN classification

ON articles.articleID = classification.articleID

WHERE classification.classID = 1

)

SET [updated_column] = updatevalue

</pre></div>

With long name of table:

<div class="mw-highlight mw-highlight-lang-sql mw-content-ltr" dir="ltr"><pre>UPDATE MyMainTable AS a

SET a.LName = Smith

WHERE a.PeopleID = 1235

</pre></div>

<div class="mw-heading mw-heading2"><h2 id="Potential_issues">Potential issues</h2></div>

<ul><li>See <a href="Halloween_Problem" title="Halloween Problem">Halloween Problem</a>. It is possible for certain kinds of <code>UPDATE</code> statements to become an <a href="Infinite_loop" title="Infinite loop">infinite loop</a> when the <code>WHERE</code> clause and one or more <code>SET</code> clauses may utilize an intertwined <a href="Index_(database)" class="mw-redirect" title="Index (database)">index</a>.</li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}

/* end https://en.wikipedia.org/ */

</style><div class="reflist">

<li id="cite_note-1"><a href="#cite_ref-1">^</a> <a rel="nofollow" class="external free" href="http://dev.mysql.com/doc/refman/5.0/en/update.html">http://dev.mysql.com/doc/refman/5.0/en/update.html</a> simplified from this page

</li>

/* start https://en.wikipedia.org/ */

.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}

/* end https://en.wikipedia.org/ */

</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.postgresql.org/docs/8.1/static/sql-update.html">"UPDATE"</a>. January 2012.</cite>

</li>

<li id="cite_note-3"><a href="#cite_ref-3">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://stackoverflow.com/q/40562962">"SQL - Update a table column, then the other column with updated value of the former. MySQL / PostgreSQL differ"</a>.</cite>

</li>

</ol></div></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}

/* end https://en.wikipedia.org/ */

</style><style data-mw-deduplicate="TemplateStyles:r1236075235">

/* start https://en.wikipedia.org/ */

.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output .navbox-subgroup{background-color:#fdfdfd}.mw-parser-output .navbox-list{line-height:1.5em;border-color:#fdfdfd}.mw-parser-output .navbox-list-with-group{text-align:left;border-left-width:2px;border-left-style:solid}.mw-parser-output tr+tr>.navbox-abovebelow,.mw-parser-output tr+tr>.navbox-group,.mw-parser-output tr+tr>.navbox-image,.mw-parser-output tr+tr>.navbox-list{border-top:2px solid #fdfdfd}.mw-parser-output .navbox-title{background-color:#ccf}.mw-parser-output .navbox-abovebelow,.mw-parser-output .navbox-group,.mw-parser-output .navbox-subgroup .navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}

/* end https://en.wikipedia.org/ */

</style><style data-mw-deduplicate="TemplateStyles:r920966791">

/* start https://en.wikipedia.org/ */

.mw-parser-output span.smallcaps{font-variant:small-caps}.mw-parser-output span.smallcaps-smaller{font-size:85%}

/* end https://en.wikipedia.org/ */

</style></div><div role="navigation" class="navbox" aria-labelledby="SQL70" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><style data-mw-deduplicate="TemplateStyles:r1239400231">

/* start https://en.wikipedia.org/ */

.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}

/* end https://en.wikipedia.org/ */

</style><div id="SQL70" style="font-size:114%;margin:0 4em"><a href="SQL" title="SQL">SQL</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Versions</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="SEQUEL" class="mw-redirect" title="SEQUEL">SEQUEL</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="SQL_reserved_words" class="mw-redirect" title="SQL reserved words">Keywords</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Create_(SQL)" class="mw-redirect" title="Create (SQL)">Create</a></li>

<li><a href="Delete_(SQL)" title="Delete (SQL)">Delete</a></li>

<li><a href="Group_by_(SQL)" title="Group by (SQL)">Group by</a></li>

<li><a href="Having_(SQL)" title="Having (SQL)">Having</a></li>

<li><a href="Insert_(SQL)" title="Insert (SQL)">Insert</a></li>

<li><a href="Merge_(SQL)" title="Merge (SQL)">Merge</a></li>

<li><a href="Order_by" title="Order by">Order by</a></li>

<li><a href="Prepare_(SQL)" class="mw-redirect" title="Prepare (SQL)">Prepare</a></li>

<li><a href="Select_(SQL)" title="Select (SQL)">Select</a></li>

<li><a href="Truncate_(SQL)" title="Truncate (SQL)">Truncate</a></li>

<li><a href="Set_operations_(SQL)" title="Set operations (SQL)">Union</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Edgar_F._Codd" title="Edgar F. Codd">Edgar Codd</a></li>

<li><a href="Relational_database" title="Relational database">Relational database</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">ISO/IEC SQL parts</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li>Framework</li>

<li>Foundation</li>

<li><a href="SQL/CLI" class="mw-redirect" title="SQL/CLI">Call-Level Interface</a></li>

<li><a href="SQL/PSM" title="SQL/PSM">Persistent Stored Modules</a></li>

<li><a href="SQL/MED" title="SQL/MED">Management of External Data</a></li>

<li><a href="SQL/OLB" title="SQL/OLB">Object Language Bindings</a></li>

<li><a href="SQL/Schemata" title="SQL/Schemata">Information and Definition Schemas</a></li>

<li><a href="SQL/JRT" title="SQL/JRT">SQL Routines and Types for the Java Programming Language</a></li>

<li><a href="SQL/XML" title="SQL/XML">XML-Related Specifications</a></li></ul>

</div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-01-25" href="https://en.wikipedia.org/wiki/?title=Update_(SQL)&oldid=1271809598">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

</div>

</div></div>

</div>

</main>

</div>

</body></html>