У овом одељку учимо различите начине за брисање дупликата редова МиСКЛ и Орацле . Ако је СКЛ табела садржи дупликате редова, онда морамо да уклонимо дупликате редова.

Припрема узорака података

Скрипта креира табелу под називом контакти .

 DROP TABLE IF EXISTS contacts; CREATE TABLE contacts ( id INT PRIMARY KEY AUTO_INCREMENT, first_name VARCHAR(30) NOT NULL, last_name VARCHAR(25) NOT NULL, email VARCHAR(210) NOT NULL, age VARCHAR(22) NOT NULL ); 

У горњу табелу убацили смо следеће податке.

 INSERT INTO contacts (first_name,last_name,email,age) VALUES ('Kavin','Peterson','[email protected]','21'), ('Nick','Jonas','[email protected]','18'), ('Peter','Heaven','[email protected]','23'), ('Michal','Jackson','[email protected]','22'), ('Sean','Bean','[email protected]','23'), ('Tom ','Baker','[email protected]','20'), ('Ben','Barnes','[email protected]','17'), ('Mischa ','Barton','[email protected]','18'), ('Sean','Bean','[email protected]','16'), ('Eliza','Bennett','[email protected]','25'), ('Michal','Krane','[email protected]','25'), ('Peter','Heaven','[email protected]','20'), ('Brian','Blessed','[email protected]','20'); ('Kavin','Peterson','[email protected]','30'), 

Извршавамо скрипту за поновно креирање тестних података након извршавања а ИЗБРИШИ изјава .

Упит враћа податке из табеле контаката:

 SELECT * FROM contacts ORDER BY email; 

Следећи СКЛ упит враћа дупликате е-поште из табеле контаката:

 SELECT email, COUNT(email) FROM contacts GROUP BY email HAVING COUNT (email) > 1; 

Имамо три реда са дупликат е-поруке.

регресионо тестирање у тестирању софтвера

(А) Избришите дупле редове помоћу наредбе ДЕЛЕТЕ ЈОИН

 DELETE t1 FROM contacts t1 INNERJOIN contacts t2 WHERE t1.id <t2.id and t1.email="t2.email;" < pre> <p> <strong>Output:</strong> </p> <pre> Query OK, three rows affected (0.10 sec) </pre> <p>Three rows had been deleted. We execute the query, given below to finds the <strong>duplicate emails</strong> from the table.</p> <pre> SELECT email, COUNT (email) FROM contacts GROUP BY email HAVING COUNT (email) &gt; 1; </pre> <p>The query returns the empty set. To verify the data from the contacts table, execute the following SQL query:</p> <pre> SELECT * FROM contacts; </pre> <br> <table class="table"> <tr> <td>id</td> <td>first_name</td> <td>last_name</td> <td>Email</td> <td>age</td> </tr> <tr> <td>7</td> <td>Ben</td> <td>Barnes</td> <td> [email protected] </td> <td>21</td> </tr> <tr> <td>13</td> <td>Brian</td> <td>Blessed</td> <td> [email protected] </td> <td>18</td> </tr> <tr> <td>10</td> <td>Eliza</td> <td>Bennett</td> <td> [email protected] </td> <td>23</td> </tr> <tr> <td>1</td> <td>Kavin</td> <td>Peterson</td> <td> [email protected] </td> <td>22</td> </tr> <tr> <td>8</td> <td>Mischa</td> <td>Barton</td> <td> [email protected] </td> <td>20</td> </tr> <tr> <td>11</td> <td>Micha</td> <td>Krane</td> <td> [email protected] </td> <td>17</td> </tr> <tr> <td>4</td> <td>Michal</td> <td>Jackson</td> <td> [email protected] </td> <td>18</td> </tr> <tr> <td>2</td> <td>Nick</td> <td>Jonas</td> <td> [email protected] </td> <td>16</td> </tr> <tr> <td>3</td> <td>Peter</td> <td>Heaven</td> <td> [email protected] </td> <td>25</td> </tr> <tr> <td>5</td> <td>Sean</td> <td>Bean</td> <td> [email protected] </td> <td>20</td> </tr> <tr> <td>6</td> <td>Tom</td> <td>Baker</td> <td> [email protected] </td> <td>30</td> </tr> </table> <p>The rows <strong>id&apos;s 9, 12, and 14</strong> have been deleted. We use the below statement to delete the duplicate rows:</p> <p>Execute the script for <strong>creating</strong> the contact.</p> <pre> DELETE c1 FROM contacts c1 INNERJ OIN contacts c2 WHERE c1.id &gt; c2.id AND c1.email = c2.email; </pre> <br> <table class="table"> <tr> <td>id</td> <td>first_name</td> <td>last_name</td> <td>email</td> <td>age</td> </tr> <tr> <td>1</td> <td>Ben</td> <td>Barnes</td> <td> [email protected] </td> <td>21</td> </tr> <tr> <td>2</td> <td> <strong>Kavin</strong> </td> <td> <strong>Peterson</strong></td> <td> <strong> [email protected] </strong> </td> <td> <strong>22</strong> </td> </tr> <tr> <td>3</td> <td>Brian</td> <td>Blessed</td> <td> [email protected] </td> <td>18</td> </tr> <tr> <td>4</td> <td>Nick</td> <td>Jonas</td> <td> [email protected] </td> <td>16</td> </tr> <tr> <td>5</td> <td>Michal</td> <td>Krane</td> <td> [email protected] </td> <td>17</td> </tr> <tr> <td>6</td> <td>Eliza</td> <td>Bennett</td> <td> [email protected] </td> <td>23</td> </tr> <tr> <td>7</td> <td>Michal</td> <td>Jackson</td> <td> [email protected] </td> <td>18</td> </tr> <tr> <td>8</td> <td> <strong>Sean</strong> </td> <td> <strong>Bean</strong> </td> <td> <strong> [email protected] </strong> </td> <td> <strong>20</strong> </td> </tr> <tr> <td>9</td> <td>Mischa</td> <td>Barton</td> <td> [email protected] </td> <td>20</td> </tr> <tr> <td>10</td> <td> <strong>Peter</strong> </td> <td> <strong>Heaven</strong> </td> <td> <strong> [email protected] </strong> </td> <td> <strong>25</strong> </td> </tr> <tr> <td>11</td> <td>Tom</td> <td>Baker</td> <td> [email protected] </td> <td>30</td> </tr> </table> <h2>(B) Delete duplicate rows using an intermediate table</h2> <p>To delete a duplicate row by using the intermediate table, follow the steps given below:</p> <p> <strong>Step 1</strong> . Create a new table <strong>structure</strong> , same as the real table:</p> <pre> CREATE TABLE source_copy LIKE source; </pre> <p> <strong>Step 2</strong> . Insert the distinct rows from the original schedule of the database:</p> <pre> INSERT INTO source_copy SELECT * FROM source GROUP BY col; </pre> <p> <strong>Step 3</strong> . Drop the original table and rename the immediate table to the original one.</p> <pre> DROP TABLE source; ALTER TABLE source_copy RENAME TO source; </pre> <p>For example, the following statements delete the <strong>rows</strong> with <strong>duplicate</strong> emails from the contacts table:</p> <pre> -- step 1 CREATE TABLE contacts_temp LIKE contacts; -- step 2 INSERT INTO contacts_temp SELECT * FROM contacts GROUP BY email; -- step 3 DROP TABLE contacts; ALTER TABLE contacts_temp RENAME TO contacts; </pre> <h2>(C) Delete duplicate rows using the ROW_NUMBER() Function</h2> <h4>Note: The ROW_NUMBER() function has been supported since MySQL version 8.02, so we should check our MySQL version before using the function.</h4> <p>The following statement uses the <strong>ROW_NUMBER ()</strong> to assign a sequential integer to every row. If the email is duplicate, the row will higher than one.</p> <pre> SELECT id, email, ROW_NUMBER() OVER (PARTITION BY email ORDER BY email ) AS row_num FROM contacts; </pre> <p>The following SQL query returns <strong>id list</strong> of the duplicate rows:</p> <pre> SELECT id FROM (SELECT id, ROW_NUMBER() OVER ( PARTITION BY email ORDER BY email) AS row_num FROM contacts ) t WHERE row_num&gt; 1; </pre> <p> <strong>Output:</strong> </p> <table class="table"> <tr> <td>id</td> </tr> <tr> <td>9</td> </tr> <tr> <td>12</td> </tr> <tr> <td>14</td> </tr> </table> <h2>Delete Duplicate Records in Oracle</h2> <p>When we found the duplicate records in the table, we had to delete the unwanted copies to keep our data clean and unique. If a table has duplicate rows, we can delete it by using the <strong>DELETE</strong> statement.</p> <p>In the case, we have a column, which is not the part of <strong>group</strong> used to <strong>evaluate</strong> the <strong>duplicate</strong> records in the table.</p> <p>Consider the table given below:</p> <table class="table"> <tr> <td>VEGETABLE_ID</td> <td>VEGETABLE_NAME</td> <td>COLOR</td> </tr> <tr> <td>01</td> <td>Potato</td> <td>Brown</td> </tr> <tr> <td>02</td> <td>Potato</td> <td>Brown</td> </tr> <tr> <td>03</td> <td>Onion</td> <td>Red</td> </tr> <tr> <td>04</td> <td>Onion</td> <td>Red</td> </tr> <tr> <td>05</td> <td>Onion</td> <td>Red</td> </tr> <tr> <td>06</td> <td>Pumpkin</td> <td>Green</td> </tr> <tr> <td>07</td> <td>Pumpkin</td> <td>Yellow</td> </tr> </table> <br> <pre> -- create the vegetable table CREATE TABLE vegetables ( VEGETABLE_ID NUMBER generated BY DEFAULT AS ID ENTITY, VEGETABLE_NAME VARCHAR2(100), color VARCHAR2(20), PRIMARY KEY (VEGETABLE_ID) ); </pre> <br> <pre> -- insert sample rows INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES(&apos;Potato&apos;,&apos;Brown&apos;); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES(&apos;Potato&apos;,&apos;Brown&apos;); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES(&apos;Onion&apos;,&apos;Red&apos;); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES(&apos;Onion&apos;,&apos;Red&apos;); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES(&apos;Onion&apos;,&apos;Red&apos;); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES(&apos;Pumpkin&apos;,&apos;Green&apos;); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES(&apos;Pumpkin&apos;,&apos;Yellow&apos;); </pre> <br> <pre> -- query data from the vegetable table SELECT * FROM vegetables; </pre> <p>Suppose, we want to keep the row with the highest <strong>VEGETABLE_ID</strong> and delete all other copies.</p> <pre> SELECT MAX (VEGETABLE_ID) FROM vegetables GROUP BY VEGETABLE_NAME, color ORDER BY MAX(VEGETABLE_ID); </pre> <br> <table class="table"> <tr> <td>MAX(VEGETABLE_ID)</td> </tr> <tr> <td>2</td> </tr> <tr> <td>5</td> </tr> <tr> <td>6</td> </tr> <tr> <td>7</td> </tr> </table> <p>We use the <strong>DELETE</strong> statement to delete the rows whose values in the <strong>VEGETABLE_ID COLUMN</strong> are not the <strong>highest</strong> .</p> <pre> DELETE FROM vegetables WHERE VEGETABLE_IDNOTIN ( SELECT MAX(VEGETABLE_ID) FROM vegetables GROUP BY VEGETABLE_NAME, color ); </pre> <p>Three rows have been deleted.</p> <pre> SELECT *FROM vegetables; </pre> <br> <table class="table"> <tr> <td>VEGETABLE_ID</td> <td>VEGETABLE_NAME</td> <td>COLOR</td> </tr> <tr> <td> <strong>02</strong> </td> <td>Potato</td> <td>Brown</td> </tr> <tr> <td> <strong>05</strong> </td> <td>Onion</td> <td>Red</td> </tr> <tr> <td> <strong>06</strong> </td> <td>Pumpkin</td> <td>Green</td> </tr> <tr> <td> <strong>07</strong> </td> <td><pumpkin td> <td>Yellow</td> </pumpkin></td></tr> </table> <p>If we want to keep the row with the lowest id, use the <strong>MIN()</strong> function instead of the <strong>MAX()</strong> function.</p> <pre> DELETE FROM vegetables WHERE VEGETABLE_IDNOTIN ( SELECT MIN(VEGETABLE_ID) FROM vegetables GROUP BY VEGETABLE_NAME, color ); </pre> <p>The above method works if we have a column that is not part of the group for evaluating duplicate. If all values in the columns have copies, then we cannot use the <strong>VEGETABLE_ID</strong> column.</p> <p>Let&apos;s drop and create the <strong>vegetable</strong> table with a new structure.</p> <pre> DROP TABLE vegetables; CREATE TABLE vegetables ( VEGETABLE_ID NUMBER, VEGETABLE_NAME VARCHAR2(100), Color VARCHAR2(20) ); </pre> <br> <pre> INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES(1,&apos;Potato&apos;,&apos;Brown&apos;); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES(1, &apos;Potato&apos;,&apos;Brown&apos;); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color)VALUES(2,&apos;Onion&apos;,&apos;Red&apos;); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color)VALUES(2,&apos;Onion&apos;,&apos;Red&apos;); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES(2,&apos;Onion&apos;,&apos;Red&apos;); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES(3,&apos;Pumpkin&apos;,&apos;Green&apos;); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES(&apos;4,Pumpkin&apos;,&apos;Yellow&apos;); SELECT * FROM vegetables; </pre> <br> <table class="table"> <tr> <td>VEGETABLE_ID</td> <td>VEGETABLE_NAME</td> <td>COLOR</td> </tr> <tr> <td>01</td> <td>Potato</td> <td>Brown</td> </tr> <tr> <td>01</td> <td>Potato</td> <td>Brown</td> </tr> <tr> <td>02</td> <td>Onion</td> <td>Red</td> </tr> <tr> <td>02</td> <td>Onion</td> <td>Red</td> </tr> <tr> <td>02</td> <td>Onion</td> <td>Red</td> </tr> <tr> <td>03</td> <td>Pumpkin</td> <td>Green</td> </tr> <tr> <td>04</td> <td>Pumpkin</td> <td>Yellow</td> </tr> </table> <p>In the vegetable table, the values in all columns <strong>VEGETABLE_ID, VEGETABLE_NAME</strong> , and color have been copied.</p> <p>We can use the <strong>rowid</strong> , a locator that specifies where Oracle stores the row. Because the <strong>rowid</strong> is unique so that we can use it to remove the duplicates rows.</p> <pre> DELETE FROM Vegetables WHERE rowed NOT IN ( SELECT MIN(rowid) FROM vegetables GROUP BY VEGETABLE_ID, VEGETABLE_NAME, color ); </pre> <p>The query verifies the deletion operation:</p> <pre> SELECT * FROM vegetables; </pre> <br> <table class="table"> <tr> <td>VEGETABLE_ID</td> <td>VEGETABLE_NAME</td> <td>COLOR</td> </tr> <tr> <td>01</td> <td>Potato</td> <td>Brown</td> </tr> <tr> <td>02</td> <td>Onion</td> <td>Red</td> </tr> <tr> <td>03</td> <td>Pumpkin</td> <td>Green</td> </tr> <tr> <td>04</td> <td>Pumpkin</td> <td>Yellow</td> </tr> </table> <hr></t2.id>

Три реда су обрисана. Извршавамо упит, дат у наставку, да бисмо пронашли дупликати е-поште са стола.

 SELECT email, COUNT (email) FROM contacts GROUP BY email HAVING COUNT (email) > 1; 

Упит враћа празан скуп. Да бисте верификовали податке из табеле контаката, извршите следећи СКЛ упит:

 SELECT * FROM contacts; 

Редови ид-ови 9, 12 и 14 су избрисани. Користимо доњу изјаву да избришемо дупле редове:

Извршите скрипту за стварајући контакт.

 DELETE c1 FROM contacts c1 INNERJ OIN contacts c2 WHERE c1.id > c2.id AND c1.email = c2.email; 

(Б) Избришите дупле редове користећи међутабелу

Да бисте избрисали дупли ред користећи међутабелу, следите доле наведене кораке:

Корак 1 . Направите нову табелу структура , исто као и права табела:

 CREATE TABLE source_copy LIKE source; 

Корак 2 . Уметните различите редове из оригиналног распореда базе података:

 INSERT INTO source_copy SELECT * FROM source GROUP BY col; 

Корак 3 . Испустите оригиналну табелу и преименујте непосредну табелу у оригиналну.

 DROP TABLE source; ALTER TABLE source_copy RENAME TO source; 

На пример, следеће изјаве бришу редова са дупликат имејлови из табеле са контактима:

 -- step 1 CREATE TABLE contacts_temp LIKE contacts; -- step 2 INSERT INTO contacts_temp SELECT * FROM contacts GROUP BY email; -- step 3 DROP TABLE contacts; ALTER TABLE contacts_temp RENAME TO contacts; 

(Ц) Избришите дупле редове помоћу функције РОВ_НУМБЕР().

Напомена: Функција РОВ_НУМБЕР() је подржана од МиСКЛ верзије 8.02, тако да би требало да проверимо нашу МиСКЛ верзију пре употребе функције.

Следећа изјава користи РОВ_НУМБЕР () да се сваком реду додели секвенцијални цео број. Ако је имејл дупликат, ред ће бити већи од један.

 SELECT id, email, ROW_NUMBER() OVER (PARTITION BY email ORDER BY email ) AS row_num FROM contacts; 

Враћа се следећи СКЛ упит ид листа од дупликата редова:

 SELECT id FROM (SELECT id, ROW_NUMBER() OVER ( PARTITION BY email ORDER BY email) AS row_num FROM contacts ) t WHERE row_num> 1; 

Излаз:

Избришите дуплиране записе у Орацле-у

Када смо пронашли дупликате записа у табели, морали смо да избришемо нежељене копије да би наши подаци били чисти и јединствени. Ако табела има дупле редове, можемо је избрисати помоћу ИЗБРИШИ изјава.

У случају имамо колону, која није део група користи за проценити, оценити тхе дупликат записи у табели.

Размотрите табелу дату у наставку:

мискл упдате придружите се

 -- create the vegetable table CREATE TABLE vegetables ( VEGETABLE_ID NUMBER generated BY DEFAULT AS ID ENTITY, VEGETABLE_NAME VARCHAR2(100), color VARCHAR2(20), PRIMARY KEY (VEGETABLE_ID) ); 

 -- insert sample rows INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES('Potato','Brown'); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES('Potato','Brown'); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES('Onion','Red'); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES('Onion','Red'); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES('Onion','Red'); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES('Pumpkin','Green'); INSERT INTO vegetables (VEGETABLE_NAME,color) VALUES('Pumpkin','Yellow'); 

 -- query data from the vegetable table SELECT * FROM vegetables; 

Претпоставимо да желимо да задржимо ред са највишим ВЕГЕТАБЛЕ_ИД и избришите све остале копије.

 SELECT MAX (VEGETABLE_ID) FROM vegetables GROUP BY VEGETABLE_NAME, color ORDER BY MAX(VEGETABLE_ID); 

Користимо ИЗБРИШИ наредба за брисање редова чије вредности у ВЕГЕТАБЛЕ_ИД КОЛОНА нису највиши .

 DELETE FROM vegetables WHERE VEGETABLE_IDNOTIN ( SELECT MAX(VEGETABLE_ID) FROM vegetables GROUP BY VEGETABLE_NAME, color ); 

Три реда су обрисана.

 SELECT *FROM vegetables; 

Ако желимо да задржимо ред са најнижим ИД-ом, користимо МИН() функцију уместо МАКС() функција.

 DELETE FROM vegetables WHERE VEGETABLE_IDNOTIN ( SELECT MIN(VEGETABLE_ID) FROM vegetables GROUP BY VEGETABLE_NAME, color ); 

Горњи метод функционише ако имамо колону која није део групе за процену дупликата. Ако све вредности у колонама имају копије, онда не можемо користити ВЕГЕТАБЛЕ_ИД колона.

Хајде да испустимо и направимо поврће табела са новом структуром.

 DROP TABLE vegetables; CREATE TABLE vegetables ( VEGETABLE_ID NUMBER, VEGETABLE_NAME VARCHAR2(100), Color VARCHAR2(20) ); 

 INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES(1,'Potato','Brown'); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES(1, 'Potato','Brown'); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color)VALUES(2,'Onion','Red'); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color)VALUES(2,'Onion','Red'); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES(2,'Onion','Red'); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES(3,'Pumpkin','Green'); INSERT INTO vegetables (VEGETABLE_ID,VEGETABLE_NAME,color) VALUES('4,Pumpkin','Yellow'); SELECT * FROM vegetables; 

У табели поврћа, вредности у свим колонама ВЕГЕТАБЛЕ_ИД, ВЕГЕТАБЛЕ_НАМЕ , и боја је копирана.

Можемо користити ровид , локатор који одређује где Орацле чува ред. Због ровид је јединствен тако да можемо да га користимо за уклањање дупликата редова.

 DELETE FROM Vegetables WHERE rowed NOT IN ( SELECT MIN(rowid) FROM vegetables GROUP BY VEGETABLE_ID, VEGETABLE_NAME, color ); 

Упит потврђује операцију брисања:

 SELECT * FROM vegetables;