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<\/p>\nHi,<\/p>\n
I will explain SELECT DISTINCT Statement in Oracle SQL in this post of Oracle SQL Tutorial series.<\/p>\n
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Read the previous post of this tutorial series before this.<\/strong><\/span><\/p>\n https:\/\/ittutorial.org\/sql-select-statement-and-desc-command-in-oracle-sql-oracle-sql-tutorials-1\/<\/p>\n <\/p>\n <\/p>\n SELECT DISTINCT statement is used to query only different or unique values.<\/p>\n If there are lots of duplicate values in a table, when you want to display only different (distinct) values, then you should use DISTINCT statement.<\/p>\n <\/p>\n <\/p>\n When you query the location id of hr.departmens table, you can list the multiple duplicate values in this table without using DISTINCT.<\/p>\n <\/p>\n <\/p>\n But If you use DISTINCT, then you can display only unique or distinct values as follows.<\/p>\n <\/p>\n <\/p>\n You can use DISTINCT for multiple columns as follows.<\/p>\n <\/p>\n <\/p>\n DISTINCT operator causes sorting which slows down the SQL execution time.<\/span><\/strong><\/p>\n <\/p>\n If it is possible, it is better that remove Distinct clause in Select for the SQL Query performance.<\/p>\n <\/p>\n <\/p>\nSELECT DISTINCT Statement<\/span><\/h5>\n
SELECT DISTINCT Syntax<\/span><\/h5>\n
\nSELECT<\/span>\u00a0DISTINCT<\/span>\u00a0column1<\/em>,\u00a0column2, column3... <\/em>FROM<\/span>\u00a0table_name<\/em>;<\/span><\/pre>\n<\/div>\nSQL> SELECT LOCATION_ID FROM HR.DEPARTMENTS;\r\n\r\nLOCATION_ID\r\n-----------\r\n1700\r\n1800\r\n1700\r\n2400\r\n1500\r\n1400\r\n2700\r\n2500\r\n1700\r\n1700\r\n1700\r\n\r\nLOCATION_ID\r\n-----------\r\n1700\r\n1700\r\n1700\r\n1700\r\n1700\r\n1700\r\n1700\r\n1700\r\n1700\r\n1700\r\n1700\r\n\r\nLOCATION_ID\r\n-----------\r\n1700\r\n1700\r\n1700\r\n1700\r\n1700\r\n\r\n27 rows selected.\r\n\r\nSQL><\/pre>\n
SQL> SELECT DISTINCT LOCATION_ID FROM HR.DEPARTMENTS;\r\n\r\nLOCATION_ID\r\n-----------\r\n1800\r\n2400\r\n1400\r\n2500\r\n1700\r\n2700\r\n1500\r\n\r\n7 rows selected.\r\n\r\nSQL><\/pre>\n
SQL> SELECT DISTINCT DEPARTMENT_NAME,LOCATION_ID FROM HR.DEPARTMENTS;\r\n\r\nDEPARTMENT_NAME LOCATION_ID\r\n------------------------------ -----------\r\nAdministration 1700\r\nMarketing 1800\r\nShareholder Services 1700\r\nOperations 1700\r\nSales 2500\r\nControl And Credit 1700\r\nIT Helpdesk 1700\r\nPurchasing 1700\r\nFinance 1700\r\nCorporate Tax 1700\r\nManufacturing 1700\r\n\r\nDEPARTMENT_NAME LOCATION_ID\r\n------------------------------ -----------\r\nContracting 1700\r\nNOC 1700\r\nIT 1400\r\nTreasury 1700\r\nGovernment Sales 1700\r\nExecutive 1700\r\nConstruction 1700\r\nPayroll 1700\r\nShipping 1500\r\nAccounting 1700\r\nBenefits 1700\r\n\r\nDEPARTMENT_NAME LOCATION_ID\r\n------------------------------ -----------\r\nRetail Sales 1700\r\nHuman Resources 2400\r\nPublic Relations 2700\r\nIT Support 1700\r\nRecruiting 1700\r\n\r\n27 rows selected.\r\n\r\nSQL><\/pre>\n
Do you want to learn Oracle Database for Beginners, then read the following articles.<\/span><\/h4>\n