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5 lip 2011 · You can try ALTER TABLE [TABLE_NAME] ADD UNIQUE (column1,column2,column3 ...columnN). Hope this helps cheers. [ID] [int] IDENTITY(1,1) NOT NULL, [OrderID] [int] NOT NULL, [LineItemNumber] [int] NOT NULL, CONSTRAINT [PK_LineItems] PRIMARY KEY CLUSTERED . [ID] ASC. CONSTRAINT [UC_LineItems] UNIQUE NONCLUSTERED . [OrderID] ASC, [LineItemNumber] ASC.
PostgreSQL has a special non-standard DISTINCT ON operator that can also be used. The optional ORDER BY is for selecting which row from every group should be selected: SELECT DISTINCT ON (key) key, value FROM tableX -- ORDER BY key, <some_other_expressions> ;
26 mar 2024 · Below are methods that help us to SELECT DISTINCT on multiple columns in SQL. Syntax: SELECT DISTINCT column01, column02, ..... FROM table_name WHERE (specify the condition if required ) ; SELECT DISTINCT without WHERE Clause; SELECT DISTINCT with WHERE Clause; SELECT DISTINCT with ORDER BY clause; SELECT DISTINCT with COUNT() and GROUP BY clause
24 wrz 2023 · If you’re not familiar already, SELECT DISTINCT is a handy tool in our SQL arsenal that helps to return unique values within a database column. Here’s how we can use it in its simplest form: SELECT DISTINCT column_name FROM table_name;
16 sie 2023 · The SQL DISTINCT keyword lets you find unique rows. In this article, you’ll learn how to use it, what it can do, and understand several different examples.
23 lut 2023 · As its name implies, the DISTINCT keyword is commonly used in a SQL SELECT statement to return a distinct set of values. This tip will look at several simple examples of using SELECT DISTINCT that you can copy, paste, and edit for your needs.
The DISTINCT clause is used in the SELECT statement to filter out duplicate rows in the result set. You can use DISTINCT when you select a single column, or when you select multiple columns as we did in our example. This is especially useful when you want to simplify your dataset and focus on unique records, making data analysis more efficient ...
