how to find unique element in sql
DISTINCT
- select distinct * from employees; ==>
retrieves any row if it has at
least a single unique column.
- select distinct first_name from employees; ==>
retrieves unique names
from table. (removes duplicates)
- select distinct count(*) from employees;
retrieve number of unique rows
if any row has at least a single unique data.unique key in ms sql server
/* To create the Unique Key.
Unique Key constraint to enforce uniqueneess of a column i.e. the column
shouldn't allow duplicate values.*/
ALTER TABLE Table_Name
ADD CONSTRAINT Constraint_Name UNIQUE (Column_Name)Copyright © 2021 Codeinu
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