forked from docs/doc-exports
Lu, Huayi
27019c2991
Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com> Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com> Co-authored-by: Lu, Huayi <luhuayi@huawei.com> Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
48 lines
2.5 KiB
HTML
48 lines
2.5 KiB
HTML
<a name="EN-US_TOPIC_0000001819416237"></a><a name="EN-US_TOPIC_0000001819416237"></a>
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<h1 class="topictitle1">UNION</h1>
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<div id="body8662426"><p id="EN-US_TOPIC_0000001819416237__en-us_topic_0000001657865594_en-us_topic_0000001385456450_p4248204901710"><strong id="EN-US_TOPIC_0000001819416237__en-us_topic_0000001657865594_en-us_topic_0000001385456450_b2197346633181">UNION</strong> is a table creation parameter of the MERGE storage engine. Creating a table using this keyword is similar to creating a common view. The created table logically combines the data of multiple tables that are specified by UNION. DSC migrates this feature to the view creation statement in GaussDB.</p>
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<p id="EN-US_TOPIC_0000001819416237__en-us_topic_0000001657865594_en-us_topic_0000001385456450_en-us_topic_0214164504_p524954714513"><strong id="EN-US_TOPIC_0000001819416237__en-us_topic_0000001657865594_en-us_topic_0000001385456450_en-us_topic_0214164504_b39993815565">Input</strong></p>
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<pre class="screen" id="EN-US_TOPIC_0000001819416237__en-us_topic_0000001657865594_en-us_topic_0000001385456450_en-us_topic_0214164504_screen48015451078">CREATE TABLE t1 (
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a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
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message CHAR(20)
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) ENGINE=MyISAM;
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CREATE TABLE t2 (
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a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
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message CHAR(20)
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) ENGINE=MyISAM;
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CREATE TABLE total (
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a INT NOT NULL AUTO_INCREMENT,
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message CHAR(20))
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ENGINE=MyISAM UNION=(t1,t2) INSERT_METHOD=LAST;</pre>
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<p id="EN-US_TOPIC_0000001819416237__en-us_topic_0000001657865594_en-us_topic_0000001385456450_en-us_topic_0214164504_p12114173518210"><strong id="EN-US_TOPIC_0000001819416237__en-us_topic_0000001657865594_en-us_topic_0000001385456450_en-us_topic_0214164504_b424094218566">Output</strong></p>
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<pre class="screen" id="EN-US_TOPIC_0000001819416237__en-us_topic_0000001657865594_en-us_topic_0000001385456450_en-us_topic_0214164504_screen1145484581614">CREATE TABLE "public"."t1" (
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"a" SERIAL NOT NULL PRIMARY KEY,
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"message" CHAR(80)
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)
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WITH ( ORIENTATION = ROW, COMPRESSION = NO )
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NOCOMPRESS
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DISTRIBUTE BY HASH ("a");
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CREATE TABLE "public"."t2" (
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a SERIAL NOT NULL PRIMARY KEY,
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message CHAR(80)
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)
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WITH ( ORIENTATION = ROW, COMPRESSION = NO )
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NOCOMPRESS
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DISTRIBUTE BY HASH ("a");
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CREATE VIEW "public"."total"(a, message) AS
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SELECT * FROM "public"."t1"
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UNION ALL
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SELECT * FROM "public"."t2";</pre>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_16_0119.html">Table (Optional Parameters and Operations)</a></div>
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</div>
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</div>
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